Homebrew Amps: Why not GROUND the B+?

[W9JEF]

.



AM broadcast transmitters have featured a grounded B+ since the mid-1980s.

One advantage being, that no blocking capacitor is needed (reducing the inductance).
Plate current flows through the pi-network tank coil, to ground through an RF choke
at 50 ohm output, rather than across the high-Z plate. (B-minus HV fed through cathode.)

Main reason for grounded B+ ham rigs: NO lethal voltage topside,
greatly reducing the safety risk for the experimenter.

Had my homebrew grounded B+ amp (four 811-A's) in operation since 2008. :)

[kb2vxa]

No lethal voltage topside, but would you still put your finger on the top cap of a 4-400A? (;->)

Don't forget the venerable microwave oven with the grounded magnetron being one of two diodes in a half wave voltage doubler, and a current limiting split gapped core transformer.

[koØm]

Nevermind : Matthew 7:6 !

.

[kb2vxa]

We won't trample your pearls underfoot, but if you call us dogs or pigs we'll surely turn and tear you to shreds.

[koØm]

Look man, when I read Bumper's message about some pissy 811a's running 1200 volts, I went completely QRO and dashed off a dissertation ala W8JI about amplifier design; I put on my AG6K boots and started stomping on the idea of running REAL B+
under the chassis. I looked at all the words and thought about all the QRO builders and decided not to get into a back and forth with a deletant. I deleted it and made my comment.


No lethal voltage topside, but would you still put your finger on the top cap of a 4-400A? (;->)


Don't forget the venerable microwave oven with the grounded magnetron being one of two diodes in a half wave voltage doubler, and a current limiting split gapped core transformer.



We won't trample your pearls underfoot, but if you call us dogs or pigs we'll surely turn and tear you to shreds.

In the immortal words of Johnnie Cochran, "If the gloves don't fit, you must acquit." Your hand is too big while, the whole glove might fit over Bumper's head. If Bob had the strength, he would have probably weighed in with an Anti-Aircraft Gun.

.

[W9JEF]

.



I actually have--in "transmit" (HV applied, no excitation)--touched
the 811A plate caps and chassis for shock effect (on the observer).

Another advantage of having no lethal voltage topside:
no enclosure required--much better ventilation--no forced air.

According to the tube table. maximum 811-A plate voltage is 1250.
At full output, they loaf along at 1200 volts (with a brick on the key).

Of course there are always the decadent diehards who
squeal like a pig at the thought of a "perverted" B+.

[kb2vxa]

So why am I being compared to this "Bumper" whomever that is? No matter, my tongue in cheek hamster style gets a bit of getting used to.

The perverted B+ has many design advantages advantages, no sense listing the obvious, like the entertaining squeal of diehards with unshielded mic cables.

[koØm]

So why am I being compared to this "Bumper" whomever that is? No matter, my tongue in cheek hamster style gets a bit of getting used to.

Not you, "Bumper" is the one who started this thread, you know, he's the one who bumps his own Cut and Paste posts back to the top.


The perverted B+ has many design advantages advantages, no sense listing the obvious, like the entertaining squeal of diehards with unshielded mic cables.

If Bumper wants to debate amplifier design I would recommend that he checks out these sites and operators.

http://groups.yahoo.com/group/ham_amplifiers/
Amps@contesting.com
http://lists.contesting.com/mailman/listinfo/amps

.

[G7JMZ]

.



AM broadcast transmitters have featured a grounded B+ since the mid-1980s.

One advantage being, that no blocking capacitor is needed (reducing the inductance).
Plate current flows through the pi-network tank coil, to ground through an RF choke
at 50 ohm output, rather than across the high-Z plate. (B-minus HV fed through cathode.)

Main reason for grounded B+ ham rigs: NO lethal voltage topside,
greatly reducing the safety risk for the experimenter.

Had my homebrew grounded B+ amp (four 811-A's) in operation since 2008. :)

My interst is piqued, how about a few circuits for those people watching in black and white ?

[W9JEF]

Not you, "Bumper" is the one who started this thread, you know, he's the one who bumps his own Cut and Paste posts back to the top.

Actually it's copy and paste (no caps).
If that's a sin, then may the Pope grant me absolution.
It's the Island software that bumps a thread back to the top
--that or a disgruntled troll.



If Bumper wants to debate amplifier design I would recommend that he checks out these sites and operators.

http://groups.yahoo.com/group/ham_amplifiers/
Amps@contesting.com
http://lists.contesting.com/mailman/listinfo/amps

.

What's wrong with posting amplifier design info here?
It is, after all, called the "Homebrew & Mods" Forum.
If you want to debate content, there's another site
where subject matter is much more restricted. :sick:

[koØm]

.



AM broadcast transmitters have featured a grounded B+ since the mid-1980s.

One advantage being, that no blocking capacitor is needed (reducing the inductance).
Plate current flows through the pi-network tank coil, to ground through an RF choke
at 50 ohm output, rather than across the high-Z plate. (B-minus HV fed through cathode.)

Main reason for grounded B+ ham rigs: NO lethal voltage topside,
greatly reducing the safety risk for the experimenter.



My interst is piqued, how about a few circuits for those people watching in black and white ?

Hello John and welcome to the island!

.

[koØm]

What's wrong with posting amplifier design info here?
It is, after all, called the "Homebrew & Mods" Forum.
If you want to debate content, there's another site
where subject matter is much more restricted. :sick:

W9JEF, time to stand and deliver, post the diagrams to support your idea.

.

[W9JEF]

My interst is piqued, how about a few circuits for those people watching in black and white ?

Thank you, John. :)

Alas, I haven't figured out how to transfer a file;
if I try to copy & paste, and take it here, it doesn't work. :(

The pi output circuit is conventional, directly connected to the plates,
sans the blocking capacitor, but you need one in the cathode drive circuit
(or maybe couple through a well-insulated toroid transformer).
An RF choke across the output completes the circuit to ground.

Your grid current meter needs to be plastic, as it will be at B-minus potential.
B-minus goes to the filament secondary winding CT, so it needs to be well-insulated.
Bias is obtained through a small filament transformer connected bass-ackward
(secondary across the filament; rectified off the primary). T/R bias relay controlled
optically by photo resistor. Main T/R relay (120 VDC) is powered off a 10 watt Zener diode
which is part of the 23 mA bleeder circuit, which also powers the LED's (indicating & control).
The 120 VDC T/R relays being supplied by bleeder current,
it's impossible to drive the tubes with no plate voltage.

Send me an s.a.s.e., and I'll get some detailed diagrams to you.

. . . . . . 73,

. . . . . . . . Jim

[koØm]

.......I haven't figured out how to transfer a file;
if I try to copy & paste, and take it here,


Send me an s.a.s.e., and I'll get some diagrams to you.

. . . . . . 73,

. . . . . . . . Jim

Ba-ha-ha-ha-ha haaaaaa!

In other words, "I'm cannot back up my specious postings on this message board but, if you send me a Self Addressed Stamped Envelope.....FROM ENGLAND, I will send you some information......."

Ba-ha-ha-ha-ha haaaaaa!

Ba-ha-ha-ha-ha haaaaaa!

Ba-ha-ha-ha-ha haaaaaa!

.

[W9JEF]

Ba-ha-ha-ha-ha haaaaaa!

In other words, "I'm cannot back up my specious postings on this message board but, if you send me a Self Addressed Stamped Envelope.....FROM ENGLAND, I will send you some information......."

Ba-ha-ha-ha-ha haaaaaa!

Ba-ha-ha-ha-ha haaaaaa!

Ba-ha-ha-ha-ha haaaaaa!

.

Can anyone with enough smarts to homebrew an amp
not design a circuit based on the info already supplied?

[KC2UGV]

Thank you, John. :)

Alas, I haven't figured out how to transfer a file;
if I try to copy & paste, and take it here, it doesn't work. :(

The pi output circuit is conventional, directly connected to the plates,
sans the blocking capacitor, but you need one in the cathode drive circuit
(or maybe couple through a well-insulated toroid transformer).
An RF choke across the output completes the circuit to ground.

Your grid current meter needs to be plastic, as it will be at B-minus potential.
Bias is obtained through a small filament transformer connected bass-ackward
(secondary across the filament; rectified off the primary). T/R bias relay controlled
optically by photo resistor. Main T/R relay (120 VDC) is powered off a 10 watt Zener diode
which is part of the 23 mA bleeder circuit, which also powers the LED's.

Send me an s.a.s.e., and I'll get some detailed diagrams to you.

. . . . . . 73,

. . . . . . . . Jim

Pull image on your screen.
Take screen shot of diagram.
Open MSPaint.
Ctrl-V.
Save, in JPG format.
Upload as attachment.

[koØm]

Can anyone with enough smarts to homebrew an amp
not design a circuit based on the info already supplied?

The gentleman from across the ocean asked for a couple of diagrams to support your statement; we are still waiting and, we are not going to send you a SASE.

.

[W9JEF]

Pull image on your screen.
Take screen shot of diagram.
Open MSPaint.
Ctrl-V.
Save, in JPG format.
Upload as attachment.

Thanks anyway, but all "geek" to me (old dog, new tricks).
My son is the expert; it's his computer (Dell Inspiron, Windows 7).
I hardly ever get to use it (except when he's asleep).

[KC2UGV]

Thanks anyway, but all "geek" to me (old dog, new tricks).
My son is the expert; it's his computer (Dell Inspiron, Windows 7).
I hardly ever get to use it (except when he's asleep).

Display the diagrams on your computer screen.
Hit Atl-PrtScrn.
Open MSPaint (Windows Key + R, and type mspaint).
When paint opens, hit Ctrl-V.
Then, go to File --> Save.
Upload as an attachment.

[W9JEF]

The gentleman from across the ocean asked for a couple of diagrams to support your statement; we are still waiting and, we are not going to send you a SASE.

.

It may take a while--my son is still sleeping.

If our friend across the pond will send the stamps loose in the envelope
(which my daughter in London can use), I'll buy the return postage. :)

[W5BRM]

lol why does this part of the thread remind me of this??


http://www.youtube.com/watch?v=8cuihrjLNAo

[koØm]

Thanks anyway, but all "geek" to me (old dog, new tricks).
My son is the expert; it's his computer (Dell Inspiron, Windows 7).
I hardly get to use it (except when he's asleep).

Let's not get side tracked, it isn't about your son or his computer, who made it or, what operating system it is running.

The topic was about Grounding B+ in a HF amplifier; you were asked by your peers to support your statement with documentation.

You could not do this. Instead, you attempted to stall for time with a supercilious request of a SASE for a fellow 3,000 miles away. Cory threw you a lifeline directly instructing you on how to bring your response to this thread; you crawfished out. Cory should send you a SASE requesting payment for his time in attempting to edify you.

In other words:

12137
.

[W9JEF]

Display the diagrams on your computer screen.
Hit Atl-PrtScrn.
Open MSPaint (Windows Key + R, and type mspaint).
When paint opens, hit Ctrl-V.
Then, go to File --> Save.
Upload as an attachment.

Alas, "Display the diagrams on your computer screen" finds me at a loss.
But this old dog can learn new tricks (slow learning disability).
Today's time will be used to apply a couple coats of Minwax Polyurethane to
some cabinetry I just built (to dry while we go to the Siloam Springs Dogwood Festival).

[WØTKX]

Snipping Tool in Win7, better than screenshots.

But the point is moot, Mel snipped it better. ;)

Bumper? :clap:

[W9JEF]

Snipping Tool in Win7, better than screenshots.

But the point is moot, Mel snipped it better. ;)

Bumper? :clap:

A psycho-schematic? :sick:

[N2NH]

lol why does this part of the thread remind me of this??


http://www.youtube.com/watch?v=8cuihrjLNAo

You are not alone. Excellent comparison.


Snipping Tool in Win7, better than screenshots.

But the point is moot, Mel snipped it better. ;)

Bumper? :clap:

Yep. :lol:

[kb2vxa]

Why do I get the distinct impression the usual JEF obfuscation is a $5 foot long (afoot for those who don't get Subway commercials) here? If I can do it anybody can, and over on AM Fone if you click on thumbnails you can see them full size.

[N2NH]

...In other words:

12137
.

:yes: That too.

[W9JEF]

Let's not get side tracked, it isn't about your son or his computer, who made it or, what operating system it is running.

The topic was about Grounding B+ in a HF amplifier; you were asked by your peers to support your statement with documentation.

You could not do this. Instead, you attempted to stall for time with a supercilious request of a SASE for a fellow 3,000 miles away. Cory threw you a lifeline directly instructing you on how to bring your response to this thread; you crawfished out. Cory should send you a SASE requesting payment for his time in attempting to edify you.

In other words:
12137



At least my Island user name matches my FCC callsign. ;)

[KC2UGV]

At least my Island user name matches my FCC callsign. ;)

So, are ya posting that diagram today? I see you're on the computer, should take all of about 3 minutes to do.

[W9JEF]

So, are ya posting that diagram today? I see you're on the computer, should take all of about 3 minutes to do.

Got a dental appointment in a half hour.

Thank you for your patience. :)

[W9JEF]

.



Now where was I?

Oh, yeah--the unanswered question:

Homebrew Amps: Why not ground the B+?

Eliminating the blocking capacitor reduces the
inductance (at the VHF parasitic frequencies).

No RF choke at the plate impedance ends the problem of series resonances.

Grounded B+. Feed B minus to the cathode(s)/filament transformer center tap.

Assuming you passed an amateur radio licensing test,
do I really need to draw you a diagram? :lol:

[KC2UGV]

Well, I don't understand math and words, as it's just too complicated. The most interesting ideas can be conveyed by pictures or words. Words are failing you, so some diagrams (aka pictures).

[W9JEF]

Well, I don't understand math and words, as it's just too complicated. The most interesting ideas can be conveyed by pictures or words. Words are failing you, so some diagrams (aka pictures).

CORRECTION: Words (simple ones at that) are failing YOU.

Anyone who has passed the FCC Amateur radio test understands math.

What do you not understand about grounding and B+?

[KC2UGV]

CORRECTION: Words (simple ones at that) are failing YOU.

Anyone who has passed the FCC Amateur radio test understands math.

What do you not understand about grounding and B+?

I suppose you don't understand it yourself, since you can't show me it in pictures. Oh well.

[W9JEF]

I suppose you don't understand it yourself, since you can't show me it in pictures. Oh well.


Those who haven't learned to read need pictures.

For those who're literate, words can convey ideas.

[KC2UGV]

Those who haven't learned to read need pictures.

For those who're literate, words can convey ideas.

But your words are not adequately conveying your ideas. So, since you can't convey the idea in terms a 6 year old could understand, and can't draw it in a picture, you must not understand it yourself. It's ok.

[W9JEF]

But your words are not adequately conveying your ideas. So, since you can't convey the idea in terms a 6 year old could understand, and can't draw it in a picture, you must not understand it yourself. It's ok.

We've now heard it directly from the horse's... er, mouth.

Obviously, your reading level is not up to that of a 6-year old. :lol:

[ad4mg]

You two need to get a room. Enough of your pissing on each others boots.

Let it go. <--- Note the warning.

[WØTKX]

Meanwhile, back in reality...

What little bit I was able to glean (readily) on the web for grounded plate/anode raised questions...

A) This works at ground for the frequencies in question, but not DC?
B) Unity gain (one), maybe useful for pre-amps and processing?

Believe me, I ain't interested in the argument, it's a schoolyard fight without end.

[NQ6U]

From The Dictionary of Engineering (http://www.dictionaryofengineering.com/definition/grounded-plate-amplifier.html):


Grounded-Plate Amplifier:

An electron-tube amplifier in which the anode is at ground potential at the operating frequency. The input is applied between the control grid and ground, and the output is taken from between the cathode and ground. Such an amplifier features high input impedance, low output impedance, and a wide frequency response with little phase distortion. Also known as grounded-anode amplifier, cathode follower, or common-anode amplifier.

Note that this is not the same thing as grounding the B+.

http://i815.photobucket.com/albums/zz79/gyrogeerloose/goundedplateUS2252458-0.png

[W9JEF]

http://media.daykeeperjournal.com/wp-content/uploads/lightning-st-peters.jpg

[K7SGJ]

From The Dictionary of Engineering (http://www.dictionaryofengineering.com/definition/grounded-plate-amplifier.html):

Grounded-Plate Amplifier:

An electron-tube amplifier in which the anode is at ground potential at the operating frequency. The input is applied between the control grid and ground, and the output is taken from between the cathode and ground. Such an amplifier features high input impedance, low output impedance, and a wide frequency response with little phase distortion. Also known as grounded-anode amplifier, cathode follower, or common-anode amplifier.

Note that this is not the same thing as grounding the B+.

http://i815.photobucket.com/albums/zz79/gyrogeerloose/goundedplateUS2252458-0.png

Thanks for the post. I always wondered what happened to Sammy Gubin.

[N2CHX]

What a load of bullshit. BTW... Those silly things you dismiss because you think a sketchy description should be enough? They're called schematics.

I worked on dozens of AM broadcast transmitters from 250 watts to 50 kW between 1991 to present and guess what? I've never, ever seen a transmitter with the plate grounded. Ever.

Such a beast would require a negative supply to the cathode and would be inherently unstable for many reasons. You're full of shit, station. Not to mention the fact that you're a racist putz, which apparently only I have noticed. We've banned people for being racists fuckwits here, so you might want to watch your step.

[W9JEF]

By modulating the cathode voltage (negative HV DC), the plate was DC grounded,
with only RF voltage present on the output RF network, and no blocking or coupling capacitor required.
This lowered the peak voltage at the plate of the tube during positive modulation peaks,
since there is no DC bias (the audio) at the plate.


http://www.jtml.info/314R1/how%20the%20power%20rock%20modulates.pdf

[N2CHX]

.

http://www.jtml.info/314R1/how%20the%20power%20rock%20modulates.pdf

All of those transmitters have the tube decks mounted in a cabinet that floats off of cabinet ground and the plate is never at direct ground potential. So while technically you could say the plate was grounded, in reality it's not true ground and the possibility of killing yourself on the supply (supposedly the entire premise of this thread) is not only still a factor, it's actually a greater concern in these transmitters because instead of just a couple of caps, an inductor and the plate cap of the tube, you have an entire fucking metal cabinet that is floated thousands of volts off of cabinet ground.

Also, all of those transmitters have major issues with stability, like I said... ESPECIALLY the Power Rock, which is the only transmitter out of the three mentioned that has true what you could consider "grounded B+".

There's a reason that design only made it into a single AM transmitter... Sorry, but your argument about grounding the plate being such a great, safe design is BS.

[W9JEF]

Grounded B+, not grounded plate.

Sometime in the late 80's I installed a Contintental 315-R at KUOA.
That's what gave me the idea to ground the B+ in my homebrew amp.

The other day, I found the schematic (2008 was a long time ago). :)
I'll soon be redrawing the essential circuitry showing how the amp
eliminates plate blocking cap and choke, and no lethal voltage topside.
In the meantime, anyone who wants to visit the shack can witness
me putting it into transmit, and touching the plates and ground.

For some, this would seem all too good an opportunity to pass up. ;)

[N2CHX]

Grounded B+, not grounded plate.
Sometime in the late 80's I installed a Contintental 315-R at KUOA.
That's what gave me the idea to ground the B+ in my homebrew amp.
The other day, I found the schematic (2008 was a long time ago). :)
I'll soon be redrawing the essential circuitry showing how the amp
eliminates plate blocking cap and choke, and no lethal voltage topside.
In the meantime, anyone who wants to visit the shack can witness
me putting it into transmit, and touching the plates and ground.

For some, this would seem all too good an opportunity to pass up. ;)

Unless you're taking the RF output off of the cathode, which would be ridiculously inefficient, you still have chokes and there is still RF on the plate. There's still also high voltage present inside the cabinet. I fail to understand how this supposedly makes the amp so much safer and better. Do you make a habit of touching the plate circuit of tube amps? Cuz there's medication for people who do that sort of thing.

And BTW... Those 314's and 315's were a royal PITA and NOT any safer to work on. Some engineers would say they were a nightmare and even more dangerous than conventional design. Like I said, there's a reason the design was never used elsewhere.

ETA: Let me know how it works out for you when you go touching the plate of that amp of yours and the RF choke from plate to ground either opened up or has some resistance somewhere from corrosion on a connection point... Should make life interesting for you. Guess you'll find out what a few thousand negative volts in reference to ground feel like. Do report back on that. I want to know.

[N2CHX]

I'm going to expand on this...


AM broadcast transmitters have featured a grounded B+ since the mid-1980s.

A couple of models, both of which had major issues with safety and stability.


One advantage being, that no blocking capacitor is needed (reducing the inductance).
Plate current flows through the pi-network tank coil, to ground through an RF choke
at 50 ohm output, rather than across the high-Z plate. (B-minus HV fed through cathode.)

One MAJOR disadvantage being, that if your choke opens up or corrosion develops on a connecting point on the inductor(s) between ground and plate, you now have thousands of volts present on your RF output and antenna.


Main reason for grounded B+ ham rigs: NO lethal voltage topside,
greatly reducing the safety risk for the experimenter.

I see no real advantage here. In fact if anything it gives the "experimenter" a false sense of security. See above.

[W9JEF]

.



The only problem I had with the 315-R was that I had to
replace a handful of diodes every time we took a lightning hit.

I suspect the problems had to do with the PWM scheme, not the grounded B+ per se.
The RF choke completes the DC plate current path through the tank coil on the low-Z (output) side.

Yes, there's RF on the plates--you'd get a nasty burn, but it wouldn't be fatal.
With no excitation, an idling plate current indication assures that the choke is intact,
and there's no DC--or RF--on the 811-A plates to go coursing through my bod.
If by chance that choke winding should open during mid-touch,
the coupling link in my antenna tuner would complete the DC path. :)

[N2CHX]

.The only problem I had with the 315-R was that I had to
replace a handful of diodes every time we took a lightning hit.

I suspect the problems had to do with the PWM scheme, not the grounded B+ per se.
The RF choke completes the DC plate current path through the tank coil on the low-Z (output) side.

I couldn't tell you for certain, as I only worked on one of them and that was pretty early in my career, hence my not even remembering that this particular design even existed. I have heard all sorts of bad things about them however, and the fact that the design was never incorporated into any other transmitters should tell you something.



Yes, there's RF on the plates--you'd get a nasty burn, but it wouldn't be fatal.
With no excitation, an idling plate current indication assures that the choke is intact,
and there's no DC--or RF--on the 811-A plates to go coursing through my bod. :)

See my above post about what happens if there's any resistance in the plate circuit. Any positive benefits of grounding the plate are quickly negated and safety becomes a very real issue. In a traditional plate supply, resistance in the plate circuit makes it less likely to cause voltage potential at the RF output/antenna, whereas in this "grounded B+" design, when something goes wrong and you're clueless as to what exactly and you go poking around troubleshooting, the chances that lethal voltage is going to be present in places where it shouldn't be are very great.

Very bad design IMO, and I think most engineers would agree.

[W9JEF]

I couldn't tell you for certain, as I only worked on one of them and that was pretty early in my career, hence my not even remembering that this particular design even existed. I have heard all sorts of bad things about them however, and the fact that the design was never incorporated into any other transmitters should tell you something.


As I mentioned, the "bad things" were related to the pulse-width modulation,
and the C-Quam stereo system, and not the issue of grounded B+ itself.

How does grounding the B+ of a linear amplifier and
feeding negative voltage to the cathode become a problem?




See my above post about what happens if there's any resistance in the plate circuit. Any positive benefits of grounding the plate are quickly negated and safety becomes a very real issue. In a traditional plate supply, resistance in the plate circuit makes it less likely to cause voltage potential at the RF output/antenna, whereas in this "grounded B+" design, when something goes wrong and you're clueless as to what exactly and you go poking around troubleshooting, the chances that lethal voltage is going to be present in places where it shouldn't be are very great.

The poking around would be with the output
connected to a 50 ohm pure resistance.
At 110 mA idling current? Do the math.
(assuming the unlikely failure of the choke).



Very bad design IMO, and I think most engineers would agree.

Well, the grounded B+ amp worked fine the first time she was turned on.

Brick on the key, she delivers 500 watts. On SSB, peaks at 600.

Worked Christmas Island on 160 CW.

Unsolicited "excellent audio quality" reports in the CQ 160 test.

[W7XF]

:sleep::deadhorse:

[suddenseer]

Someone's grid doth float.

[W7XF]

IIRC, the last widespread use of grounded B+ was Lucas automotive electrics....and here is an advertisement from Lucas:


https://www.youtube.com/watch?v=U4XbV3gCm2Y

[KG4CGC]

Luck Fucas.

[W9JEF]

.



I'm just as amicable as the next, when it comes to the good-natured banter (at least on my part).

The ridicule is actually cool...it comes with any radical (in this case, proven) innovation.
SSB was called "Silly Sideband" by the decadent diehard denizens of full-carrier AM on 75. :sick:

. . . . . . . . . .; . .. . . . . . . . . . . . . . . . . . . . . . . . . . ;)

[n2ize]

.



I'm just as amicable as the next, when it comes to the good-natured banter (at least on my part).

The ridicule is actually cool...it comes with any radical (in this case, proven) innovation.
SSB was called "Silly Sideband" by the decadent diehard denizens of full-carrier AM on 75. :sick:

. . . . . . . . . .; . .. . . . . . . . . . . . . . . . . . . . . . . . . . ;)
No, we call SSB "Slopbucket" in the 75/160 meter AM'er vernacular. . Never heard anyone call it "silly sideband". And believe it or not many of use use "slopbucket" (SSB) and recognize it as a worthwhile and valid mode as wel. It's just that AM is our preferred mode. "Slopbucket" is generally used as a derogatory term mainly directed at sidebanders (slopbucketeers) who start operating right on the same frequency as an AM QSO in progress or just a kc or 2 off to the side.

[kb2vxa]

Oh, you noticed that dija? If you want to be an AM Gangsta you'll have to build a Timtron SBE, slop bucket eliminator. Just don't confuse it with Side Band Engineering or Society of Broadcast Engineers.

[W9JEF]

No, we call SSB "Slopbucket" in the 75/160 meter AM'er vernacular. . Never heard anyone call it "silly sideband". And believe it or not many of use use "slopbucket" (SSB) and recognize it as a worthwhile and valid mode as wel. It's just that AM is our preferred mode. "Slopbucket" is generally used as a derogatory term mainly directed at sidebanders (slopbucketeers) who start operating right on the same frequency as an AM QSO in progress or just a kc or 2 off to the side.

Back in the mid-'50's, the "sidewinders" occupied just the top few kc's of the 75 meter band.
Unless you turned on and adjusted the BFO, they sounded like Donald Duck. The rcvr's fast AVC
(pumping the gain between syllables) made "silly sideband" signals seem excessively broad.

[N2NH]

Hmmm... argues with a transmitter engineer with years of experience over a moot point.

I suggest if you really believe that this design is viable you build one and let us know how it turns out. I personally agree with Kelli and think it would be a hazard, but WTF do I know?

[KG4CGC]

Hmmm... argues with a transmitter engineer with years of experience over a moot point.

I suggest if you really believe that this design is viable you build one and let us know how it turns out. I personally agree with Kelli and think it would be a hazard, but WTF do I know?

I know. If you're going to argue with Kelli over this, then you're true intentions on the Island are exposed.

[N2NH]

I know. If you're going to argue with Kelli over this, then you're true intentions on the Island are exposed.

Well, JEF could make a YouTube video of his efforts, diagram it on a schematic and show us the error of our ways. Or not. I think that the second version would be the outcome of this, but he's out to make this point, so this would be a good way to see who is right or wrong. I take no responsibility for any injury, death and/or liability resulting from this.

Otherwise knock yerself out.

[KC2UGV]

Well, JEF could make a YouTube video of his efforts, diagram it on a schematic and show us the error of our ways. Or not. I think that the second version would be the outcome of this, but he's out to make this point, so this would be a good way to see who is right or wrong. I take no responsibility for any injury, death and/or liability resulting from this.

Otherwise knock yerself out.

Except, he's been queried to supply a diagram/schematic/etc of his work, and has refused to do so for some reason. I think it's something about repeatability of experimentation, or some other witchcraft sciency stuff.

[kb2vxa]

Gee, I hope this works.........

[W9JEF]

Someone's grid doth float.

Good point. A grounded grid RF amplifier,
by definition, has a (wait for it)
. . . . . . . a grounded grid. :)
Which may seem somewhat of an "issue"
if the cathode potential is thousands of volts. :wtf:

But wait...

The grid only need be grounded at RF,
so the 4 811-A grids are each bypassed to ground
(chassis) with .01 @ 2 kV disk ceramics.

Being zero-bias tubes in class B, the 811-A
grid bus connects directly to B minus.
In stand-by, it switches to a bias supply
(rectified DC off the primary of a small transformer
with 6.3 v. secondary across the 811-A filaments.

Since the issue of experience has been brought up,
built my first successful radio transmitter in 1953. :)
Amateur Extra & First Class Radiotelephone licenses in 1957.
Back then the FCC ham exams had us drawing diagrams.
Emergency repair to AM b'cast xmtr (replaced a type 45 tube), early 60's.

Back in 1989 when I was CE at KUOA, we installed
a 5 kW AM transmitter whose final's B+ was grounded.
That's when I decided to build my amp that way.
It worked flawlessly the first time--in 2008-- 8) that I turned it on.

I did need to prune the tank inductance for the various bands;
having no lethal voltage topside made it much, much safer.
Of course one should turn off the HV before poking around.


Alas, my computer expertise is lacking (all those BC xmtrs had TUBE finals).
So I need to find the time (housework, yard work, homeschooling come first)
to learn how to get imported camera images to where I can paste into a post.

In the meantime, if someone with more IT savvy than me will volunteer,
I'll send schematics (by snail mail) that they then successfully be posted.
If anyone cares to visit the QTH (perhaps on the way to Dayton)
I'll be happy to demo the working grounded B+ amplifier.

To sum up the electrical reasons for a grounded B+ RF power amplifier:
1. No high-Z plate RF choke (eliminating the series resonance issue).
2. No plate DC blocking capacitor (inductive at VHF parasitic frequencies.)

But the main motive for the OP:
that it save just one experimenter
from going SK before his or her time.

. . . . . . . . . . . . . . .73,
. . . . . . . . . . . . . . . .Jim

[KC2UGV]

In the meantime, if someone with more IT savvy than me will volunteer,
I'll send schematics (by snail mail) that they then successfully be posted.

Mail 'em my way. My FCC address is good to go.

[W9JEF]

Mail 'em my way. My FCC address is good to go.

Thank you, sir.

. . . . 73,

. . . . . Jim

[W9JEF]

.



It just occurred to me, that the biggest issue with a grounded B+ amplifier is,
the filament transformer secondary must be insulated against the high voltage
which is applied to the center tap--plus the peak AC voltage of the primary.
(My surplus 20 amp transformer had these impressive ceramic insulators
for the secondary, so I correctly assumed it could take the high DC voltage.) :)

Many of the transformers that can power four 811-A filaments (20 A, total)
may not be sufficiently insulated for an amplifier featuring a grounded B+.

So, I am now working on a simple solution:
a well-insulated secondary winding of #12
through the core of a variable autotransformer (Variac).
It could eliminate the need for a bifilar filament choke,
requiring only a single-wound low current choke for the DC.

Will also be sending this along with a simple diagram, Corey.
But you must promise not to modify--genetically or otherwise. ;)

Okay? :)

[KC2UGV]

.



It just occurred to me, that the biggest issue with a grounded B+ amplifier is,
the filament transformer secondary must be insulated against the high voltage
which is applied to the center tap--plus the peak AC voltage of the primary.
(My surplus 20 amp transformer had these impressive ceramic insulators
for the secondary, so I correctly assumed it could take the high DC voltage.) :)

Many of the transformers that can power four 811-A filaments (20 A, total)
may not be sufficiently insulated for an amplifier featuring a grounded B+.

So, I am now working on a simple solution:
a well-insulated secondary winding of #12
through the core of a variable autotransformer (Variac).
It could eliminate the need for a bifilar filament choke,
requiring only a single-wound low current choke for the DC.

Will also be sending this along with a simple diagram, Corey.
But you must promise not to modify--genetically or otherwise. ;)

Okay? :)

I'm going to scan, and upload. That's all. I've got no experience with tubes. Hell, transistor transceivers were the nom du jur by the time I was born.

[N2NH]

A week since the last post.

Either it is or isn't happening at this point. Call me very skeptical.

[KC2UGV]

nothing in the mail yet.

[W9JEF]

nothing in the mail yet.

Sorry about that. The time budget here has been strained of late
by such exigencies as the lawn mower going "kaput" (literally),
attending to the needs of Loraine and her five new kitties, and
the never ending housework and homeschooling (I'm a single father).

Nevertheless, I came up with a solution to the obvious problem with a grounded B+:
With a thousand or more negative volts on the 811-A filaments, not too many
transformers' winding insulation will withstand the peak difference in potential.

With four 45 degree 3/4 inch PVC elbows I fashioned a U-shaped insulator
which runs through the donut hole of the toroid core of a variable transformer.
It took 18 turns of #12 through this to get the 6.3 volts going to four 811-A's.
A convenient homeschool opportunity--magnetic field induced current. :)

The grounded B+ amplifier is the exact circuit DC & RF-wise.
The grid(s) still connect to B- (and bypassed to ground).
Since there's no plate blocking capacitor, plate current flows
through the tank coil, and the RFC at the low-Z output to ground.

The bias supply could be another issue, since it's transformer windings
would also need to be insulated against B-minus plus peak AC primary.
A filament transformer whose secondary is feed off the main filament
would induce very near the rated primary voltage to a diode & filter cap.

T/R switching is another issue. I found the original diagram (from 2008).
Somewhat sketchy, will need to scan old logbooks for possible revisions.
In the meantime, the amp works flawlessly, and I'd be happy to demo it.
Maybe someone to our southwest could stop here on the way back from Dayton;
we're just off US 412, close to I-49 (I-540 on old maps) convenient to I-44.

I've been having my oats w/raisins and coffee while typing this.
Another thing The Bucket List should include "not to waste"--
is a beautiful spring morning so it's back to the back porch step,
with another cup in one hand, and petting a kitty with the other. ;)
It's supposed to rain this weekend--so "back to the drawing board."

. . . . . . 73,

. . . . . . . Jim

[W7XF]

Sorry about that. The time budget here has been strained of late
by such exigencies as the lawn mower going "kaput" (literally),
attending to the needs of Loraine and her five new kitties, and
the never ending housework and homeschooling of a single father.

Nevertheless, I came up with a solution to the obvious problem with a grounded B+:
With a thousand or more negative volts on the 811-A filaments, not too many
transformers' winding insulation will withstand the peak difference in potential.

With four 45 degree 3/4 inch PVC elbows I fashioned a U-shaped insulator
which runs through the donut hole of the toroid core of a variable transformer.
It took 18 turns of #12 through this to get the 6.3 volts going to four 811-A's.
A convenient homeschool opportunity--magnetic field induced current. :)

The grounded B+ amplifier is the exact circuit DC & RF-wise.
The grid(s) still connect to B- (and bypassed to ground).
Since there's no plate blocking capacitor, plate current flows
through the tank coil, and the RFC at the low-Z output to ground.

The bias supply could be another issue, since it's transformer windings
would also need to be insulated against B-minus plus peak AC primary.
A filament transformer whose secondary is feed off the main filament
would induce very near the rated primary voltage to a diode & filter cap.

T/R switching is another issue. I found the original diagram (from 2008).
Somewhat sketchy, will need to scan old logbooks for possible revisions.
In the meantime, the amp works flawlessly, and I'd be happy to demo it.
Maybe someone to our southwest could stop here on the way to Dayton;
we're just off US 412, close to I-49 (I-540 on old maps) convenient to I-44.

I've been having my oats w/raisins and coffee while typing this.
Another thing The Bucket List should include "not to waste"--
is a beautiful spring morning so it's back to the back porch step,
with another cup in one hand, and petting a kitty with the other. ;)
It's supposed to rain this weekend--so "back to the drawing board."

. . . . . . 73,

. . . . . . . Jim

Hello.

12313

Please send tacos.

[W9JEF]

.



If you Google "grounded B+"--this thread is #1. :)

But with trolls falling all over each other, it may not be taken seriously.

is the Island an appropriate venue for an intelligent discussion of a technical subject?

Having my doubts.

[KC2UGV]

.



If you Google "grounded B+"--this thread is #1. :)

But with trolls falling all over each other, it may not be taken seriously.

is the Island an appropriate venue for an intelligent discussion of a technical subject?

Having my doubts.

Beyond what has been said, not much else to talk about until we have something concrete in front of us to critique. Nothing in the mail yet, FWIW.

[W9JEF]

Beyond what has been said, not much else to talk about until we have something concrete in front of us to critique. Nothing in the mail yet, FWIW.

Not too many here are familiar with the simple circuit of a cathode-driven RF power amplifier.
For the grounded B+ version, all you need to do with the circuit is eliminate the plate choke,
and bridge across and lose the blocking capacitor. For 811-A's (zero-bias) the grids are
bypassed to ground and connect to B-minus, along with the center tap
of the filament transformer. Couldn't be simpler.

[KC2UGV]

Not too many here are familiar with the simple circuit of a cathode-driven RF power amplifier.
For the grounded B+ version, all you need to do with the circuit is eliminate the plate choke,
and bridge across and lose the blocking capacitor. For 811-A's (zero-bias) the grids are
bypassed to ground and connect to B-minus, along with the center tap
of the filament transformer. Couldn't be simpler.

We'll all understand it more thoroughly once I receive the diagram, and post it here, I'm sure.

[N2NH]

.


But with trolls falling all over each other, it may not be taken seriously.

is the Island an appropriate venue for an intelligent discussion of a technical subject?

Having my doubts.

Until you came along, I never had any.

12323

[W9JEF]

Until you came along, I never had any.



That's what she told me.

[N2NH]

That's what she told me.

:lol:

Really. Put envelope in mailbox, raise flag. :yes:

[KC2UGV]

Nothing in the mail yet. Starting to wonder if it will ever arrive?

[W9JEF]

Hmmm... argues with a transmitter engineer with years of experience over a moot point.

"Years of experience? Homebrewed my first AM transmitter in 1954.
FCC 1st 'phone license in 1957, been working on BC xmtrs since 1961.
Certified by SBE as Senior Broadcast Engineer--AM & FM Radio--in 1985.

You think that you are making points with these constant personal attacks?
All it shows is that you cannot refute what is so. I haven't time to waste with closed minded people.



I suggest if you really believe that this design is viable you build one and let us know how it turns out.
I personally agree with Kelli and think it would be a hazard, but WTF do I know?

Kelli first argued against a grounded plate and taking output off the cathode.
My amp has the usual pi output network from the plate, sans the blocking cap.
The RF choke across the output completes the DC circuit to ground (B+).
If you read the OP, you'd see that I've already built an RF power amplifier
with a grounded B+. It turned out quite satisfactorily, and is still in use.

[W9JEF]

Nevermind : Matthew 7:6 !

.

The Matthew 7:6 comment is taken as good advice.
The original idea was to open a few minds to the advantages
of having no RF choke on the plate (avoiding series resonances
on the higher frequencies) and no plate blocking capacitor
(all the less inductance to induce VHF parasitics).

Throughout this thread, all this ad hominem vitriol.
Excuse me for mistaking this for a technical forum.

The mods will likely close the thread, which at this point
will free me from the futility of attempting a technical discussion
with so much unbridled heckling from the peanut gallery.

Please don't mistake this for whining--the message is wtf.

[N2CHX]

Taking the output off the cathode now? LOL OK.

[W9JEF]

.


Welcome back to the thread, Kelli. You're about the only one who's even
half-way interested in a technical discussion rather than only making noise.



Unless you're taking the RF output off of the cathode, which would be ridiculously inefficient,
you still have chokes and there is still RF on the plate. There's still also high voltage present
inside the cabinet. I fail to understand how this supposedly makes the amp so much safer and better.
Do you make a habit of touching the plate circuit of tube amps? Cuz there's medication
for people who do that sort of thing.

Except to make a point to skeptics, or those whose curiosity is piqued,
I don't make a habit of touching the plates of my 811-A's. But I did spend
some time trying out various taps on the tank coils for different bands.
Since the lethal voltage is not exposed above chassis, it seems safer by far
than the conventional scheme with + thousands of volts waiting to bite me. :)

[KC2UGV]

...
Kelli first argued against a grounded plate and taking output off the cathode.
My amp has the usual pi output network from the plate, sans the blocking cap.
The RF choke across the output completes the DC circuit to ground (B+).
If you read the OP, you'd see that I've already built an RF power amplifier
with a grounded B+. It turned out quite satisfactorily, and is still in use.

I'm sure we'll see exactly what you have done, when I get the diagram in the mail, and post it here. Nothing via postal yet.

[W9JEF]

Except, he's been queried to supply a diagram/schematic/etc of his work, and has refused to do so for some reason. I think it's something about repeatability of experimentation, or some other witchcraft sciency stuff.

Going by this and other such posts, methinks there's an agenda here.
For anyone with enough savvy to actually homebrew a tube amp,
from the info already given, a diagram would be a piece of cake. :)

[KC2UGV]

Going by this and other such posts, methinks there's an agenda here.
For anyone with enough savvy to actually homebrew a tube amp,
from the info already given, a diagram would be a piece of cake. :)

Then, it should be no problem to make one and post it here, or to mail it to another ham member who is willing to scan it, and post it for you.

[W9JEF]

Then, it should be no problem to make one and post it here, or to mail it to another ham member who is willing to scan it, and post it for you.

. . . Matthew 7:6

[KC2UGV]

. . . Matthew 7:6


Your magical incantations hold no sway over me.

And, on another note: Did you drop the diagram/schematic in the mail yet? Just wondering, so I know when to expect it to arrive.

[ad4mg]

The mods will likely close the thread, which at this point
will free me from the futility of attempting a technical discussion
with so much unbridled heckling from the peanut gallery.
Unlikely. When a man digs a hole in the sand, then climbs into it to continue digging, we merely observe the event with a tinge of mild amusement.

You lost it when you said you were going to mail schematics to Corey for him to scan and post.

And here we sit, tinged with mild amusement... :lol:

[W9JEF]

Your magical incantations hold no sway over me.

And, on another note: Did you drop the diagram/schematic in the mail yet?
Just wondering, so I know when to expect it to arrive.

Thanks, but in light of your incessant trivializing of my scientific acumen,
not to mention your adeptness in parsing words; my better judgment tells me
you'd find a way to justify mucking it up, so I've had realistic second thoughts.

Please review this thread--in a supposed "technical discussion" forum.
Do you really think I would want to refer my many stateside & DX contacts
made with my grounded B+ amp to this festival of insults and personal attack?

[NQ6U]

I do not have the technical savvy to argue the point one way or another and so have no dog in this fight. Send the schematic to me and I'll scan it and post it here.

"I'm good on the Zed," heh heh heh.

[W9JEF]

Unlikely. When a man digs a hole in the sand, then climbs into it to continue digging, we merely observe the event with a tinge of mild amusement.

You lost it when you said you were going to mail schematics to Corey for him to scan and post.

And here we sit, tinged with mild amusement... :lol:

And the amusement I get when I think about all the nayboobs of negativity
while working low-band DX using an amplifier that they claim will never fly. :rofl:

Can't help wishing the mods would at least keep a technical forum on track. :yes:

[KC2UGV]

Thanks, but in light of your incessant trivializing of my scientific acumen,
not to mention your adeptness in parsing words; my better judgment tells me
you'd find a way to justify mucking it up, so I've had realistic second thoughts.

Please review this thread--in a supposed "technical discussion" forum.
Do you really think I would want to refer my many stateside & DX contacts
made with my grounded B+ amp to this festival of insults and personal attack?

Hey man, I'm just going to scan and post the things. I'll even mail the hard copy back to you, if you desire. No SASE required.

[N2CHX]

And the amusement I get when I think about all the nayboobs of negativity
while working low-band DX using an amplifier that they claim will never fly. :rofl:

Can't help wishing the mods would at least keep a technical forum on track. :yes:

I never said it wouldn't work at all, I merely pointed out the issues of such an amp and I still stand by what I said. I understand how it works and I could draw a schematic of it, but to me it's moot because the problems outweigh any potential benefits. You posted this like it was some great, revolutionary thing that every ham and broadcaster was missing out on and you left me unimpressed.

[n2ize]

Going by this and other such posts, methinks there's an agenda here.
For anyone with enough savvy to actually homebrew a tube amp,
from the info already given, a diagram would be a piece of cake. :)

Okay, so you claim you can't manage to learn how to draw a digital diagram using one of several free programs out there. Then all you would have to do is save it as an image and post it here. Then you can't take the time to learn how to make a simple sketch, scan it, and post it. Then for some unknown reason you can't sketch the diagram with pencil and paper and simply drop it into an envelope and mail it to a ham who agreed to scan it and post it so that we can look at the schematic and see for ourselves how it will work. I mean you are the one claiming that simple pictures work best at explaining things more clearly than math or technical jargon or anything else. Now that we want a picture so we can get a clear understanding of exactly how this circuit works we get whining about everyone else on here and excuses, excuses, excuses, excuses.... and more excuses. :sleep: .

P.S. several posts back you even mentioned that you found the original schematic from 2008. You also said you were going to redraw it. So all you would have to do is copy it. Corey already agreed to handle the "technical stuff" i.e. simply scanning it and posting it. Now your excuse is that people here are too negative to deserve to see the sketch. Or that they will deliberately muck it up. More lame excuses... I'm calling BS on this one.

Additional P.S. Several posts back you already agreed and said you were going to drop a diagram in the mail so Corey can scan and post it. You never did.... Even more reason why I am calling BS on this.

[WØTKX]

No sale, no offense, mmmKAY.

I popped a couple of tech comments, ignored.

All along (in this thread and others) there is this attitude...

http://ia.media-imdb.com/images/M/MV5BMTc0NDg1MDc0MF5BMl5BanBnXkFtZTYwNDA5NDM2._V1._ SX450_SY304_.jpg

Most of us just have lost interest in knocking your B+ to the ground.

Sheesh. :doh:

[W9JEF]

No sale, no offense, mmmKAY.

I popped a couple of tech comments, ignored.

All along (in this thread and others) there is this attitude...

http://ia.media-imdb.com/images/M/MV5BMTc0NDg1MDc0MF5BMl5BanBnXkFtZTYwNDA5NDM2._V1._ SX450_SY304_.jpg

Most of us just have lost interest in knocking your B+ to the ground.

Sheesh. :doh:

Searched the thread for your call hoping to find the tech comments you refer to.
I guess the software only comes up with what appears in the actual texts.
I may have thought I addressed them, but apparently that's not the case;
or it was lost in the QRN. So kindly reiterate, and I'll be more than happy to oblige.

I apologize for any perceived "attitude" on my part.
Just trying to contribute to the art and science of radio. :)

[WØTKX]

nope

[W9JEF]

Okay, so you claim you can't manage to learn how to draw a digital diagram using one of several free programs out there. Then all you would have to do is save it as an image and post it here. Then you can't take the time to learn how to make a simple sketch, scan it, and post it. Then for some unknown reason you can't sketch the diagram with pencil and paper and simply drop it into an envelope and mail it to a ham who agreed to scan it and post it so that we can look at the schematic and see for ourselves how it will work. I mean you are the one claiming that simple pictures work best at explaining things more clearly than math or technical jargon or anything else. Now that we want a picture so we can get a clear understanding of exactly how this circuit works we get whining about everyone else on here and excuses, excuses, excuses, excuses.... and more excuses. :sleep: .

P.S. several posts back you even mentioned that you found the original schematic from 2008. You also said you were going to redraw it. So all you would have to do is copy it. Corey already agreed to handle the "technical stuff" i.e. simply scanning it and posting it. Now your excuse is that people here are too negative to deserve to see the sketch. Or that they will deliberately muck it up. More lame excuses... I'm calling BS on this one.

Additional P.S. Several posts back you already agreed and said you were going to drop a diagram in the mail so Corey can scan and post it. You never did.... Even more reason why I am calling BS on this.

There are legitimate excuses as well as poor excuses.
Even though "retired," I'm a single father and homeschooler.
Then there's our mama cat and her five kittens
--found a home for two of them last week.
I do spend time on the air--AND do antenna maintenance,
which for grounded verticals means mowing the lawn.
Finally fixed the mower, and spent a couple hours
cutting the (now) two-week-tall grass.

The computer belongs to my son. I'm too old a dog to quickly learn "new tricks."
The diagram from 2008 is quite sketchy, and there are revisions buried in various logbooks.

Corey may be sincere, but I've already explained the reasons for my misgivings.
Truth--is your sig not another example of the same bumptiousness I get from him?


From my sig: Besides pictures, there are words by which any serious homebrewer
familiar with vacuum tube RF amplifiers should be able to draw a schematic from.
Back when I first took my license test, drawing such schematics were a part of the exam.

Again, the trolling started with the first reply, and continues;
ignoring the memo from a mod that warns to the effect
that a technical forum no place for such bellicose tomfoolery.
Not whining--just a light-hearted wtf, that the thread is now in tatters.
But patience, please. There are priorities--I will eventually get a round tuit. ;)

[KG4CGC]

http://i25.photobucket.com/albums/c79/bebop5/drinks/570745498_VictimCard_xlarge_zps4d702eac.jpeg

[W9JEF]

I never said it wouldn't work at all, I merely pointed out the issues of such an amp and I still stand by what I said. I understand how it works and I could draw a schematic of it, but to me it's moot because the problems outweigh any potential benefits. You posted this like it was some great, revolutionary thing that every ham and broadcaster was missing out on and you left me unimpressed.

If I'm not mistaken, you alluded to some of the problems you heard about
that other broadcast engineers had with a particular broadcast transmitter,
having to do with to the pulse-width modulation, not the grounded B+ per se.
And you pilloried a grounded plate--which is NOT the same as a grounded B+.

The BC transmitter I worked with didn't feature a "floating chassis"
--otherwise the shield of the coax to the antenna would be hot.

[W9JEF]

I do not have the technical savvy to argue the point
one way or another and so have no dog in this fight. Send the schematic to me
and I'll scan it and post it here.

"I'm good on the Zed," heh heh heh.

A ray of hope in what's mostly a vast wasteland (apologies to Newton Minnow).

Whom can I trust--if not the Pope himself.

One caveat: Am I granted absolution for my admittedly sinful past?

[W7XF]

12344
A ray of hope in what's mostly a vast wasteland (apologies to Newton Minnow).

Whom can I trust--if not the Pope himself.

One caveat: Am I granted absolution for my admittedly sinful past?

[N2CHX]

If I'm not mistaken, you alluded to some of the problems you heard about
that other broadcast engineers had with a particular broadcast transmitter,
having to do with to the pulse-width modulation, not the grounded B+ per se.
And you pilloried a grounded plate--which is NOT the same as a grounded B+.

The BC transmitter I worked with didn't feature a "floating chassis"
--otherwise the shield of the coax to the antenna would be hot.

If I'm not mistaken, I put together a schematic of this circuit in my head and realized immediately how screwed up it is. Also, the plate is DC grounded and as I also said, if the choke or anything in the plate tuning circuit fails or becomes resistive through corrosion, loose screws or whatever, you've got supply voltage on your antenna. Not cool.

The other stuff was speculation based on what I had read, when you stated that you could touch the plate caps of the tubes.

Anyway I'm done with this conversation. Don't expect me to reply again. Have a nice day though.

[W9JEF]

If I'm not mistaken, I put together a schematic of this circuit in my head and realized immediately how screwed up it is. Also, the plate is DC grounded and as I also said, if the choke or anything in the plate tuning circuit fails or becomes resistive through corrosion, loose screws or whatever, you've got supply voltage on your antenna. Not cool.

The other stuff was speculation based on what I had read, when you stated that you could touch the plate caps of the tubes.

Anyway I'm done with this conversation. Don't expect me to reply again. Have a nice day though.

Loose screws??? I resemble that!

But all seriousness aside, the same hazard exists in a conventional amp
(hot B+), should a short develop in the plate blocking capacitor.


QURSTION:
If the tank coil should open, how would voltage from the plate get to the antenna???

[W9JEF]

Meanwhile, back in reality...

What little bit I was able to glean (readily) on the web for grounded plate/anode raised questions...

A) This works at ground for the frequencies in question, but not DC?
B) Unity gain (one), maybe useful for pre-amps and processing?

Believe me, I ain't interested in the argument, it's a schoolyard fight without end.


popped a couple of tech comments, ignored.


It seems you are interested, after all. ;)

Grounded plate???

Not the same as grounded B+.

Plate is grounded at DC--not RF.

The plate to B+ circuit is completed through the tank coil
and choke from output side of the pi network to ground (B+).

Unity gain??? The grounded B+ amp is NOT a cathode follower.
It's cathode driven, grid bypassed to ground, output off the plate.

[KC2UGV]

Well, I suppose once we see your schematic, we'll be able to properly critique the design.

[N2CHX]

It seems you are interested, after all. ;)

Grounded plate???

Not the same as grounded B+.

Plate is grounded at DC--not RF.

The plate to B+ circuit is completed through the tank coil
and choke from output side of the pi network to ground (B+).

Unity gain??? The grounded B+ amp is NOT a cathode follower.
It's cathode driven, grid bypassed to ground, output off the plate.

LOL so now it's a grounded grid design too? Seems like this changes every week.

[KC2UGV]

LOL so now it's a grounded grid design too? Seems like this changes every week.

This is why we will need to see a circuit diagram of some sort. Because it appears he might be talking about something with the wrong terminology. Or, the design keeps changing on his currently-used-on-low-bands amp.

[W9JEF]

Anyway I'm done with this conversation.
Don't expect me to reply again. Have a nice day though.

Seems this changes every hour. ;)

As explained in numerous previous posts:

Grid is at B minus potential (DC).

RF wise: bypassed to ground (.01mf).

[KC2UGV]

.



Grid is at B minus potential (DC).

RF wise: bypassed to ground (.01mf).


Well, once we get to see the schematic, we'll all know exactly what you're describing.

[N2CHX]

Simplified, this is it. I did your homework for you, 'JEF.

Grounded grid requires high drive and the input gets added to the output. Typical drive on a broadcast transmitter would be 1500-3000 watts in to get 10-20 kW out. However, I know of no broadcast transmitters that use grounded grid AND the supply on the cathode side.

12347

[KC2UGV]

I was going to point him here: http://www.digikey.com/schemeit

[KC2UGV]

Simplified, this is it. I did your homework for you, 'JEF.

Grounded grid requires high drive and the input gets added to the output. Typical drive on a broadcast transmitter would be 1500-3000 watts in to get 10-20 kW out. However, I know of no broadcast transmitters that use grounded grid AND the supply on the cathode side.

12347

Call me silly (As I have NO knowledge of how tubes work), but isn't this placing 5000V on the chassis?

[N2CHX]

I was going to point him here: http://www.digikey.com/schemeit

I just used my brain and GIMP. Ain't that hard.

[KC2UGV]

I just used my brain and GIMP. Ain't that hard.

That's difficult for some to do. I mean, MS Paint can take a while to figure out how to draw in too :P

[N2CHX]

Call me silly (As I have NO knowledge of how tubes work), but isn't this placing 5000V on the chassis?

Nope. It's all part of how voltage is referenced. Instead of the supply being applied to the plate and the negative side of the supply being connected to ground, in this configuration the supply is connected to the other side of the tube, backwards, so to speak. It's the same potential in regard to ground, just in a different place in regards to the tube.

[N2CHX]

What you can clearly see though, is that if L1 opens up or has any resistance, now your supply voltage gets dumped into your output, as it no longer has a direct path back to ground through the inductor.

[KC2UGV]

What you can clearly see though, is that if L1 opens up or has any resistance, now your supply voltage gets dumped into your output, as it no longer has a direct path back to ground through the inductor.

aha... Now I am seeing the issues in this design.

See 'JEF: Once you post a schematic of a circuit you are talking about, discussions can happen. Otherwise, it's "vaporware".

[N2CHX]

BTW... Before anyone says anything, the 5000 volt supply number is arbitrary. 5kV would be typical on a 2.5-5 kW transmitter. A 15-20 kW transmitter would be more like 8-10 kV.

[NQ6U]

Just reposting Kelli's schematic here so those of us who had a page break don't have to switch back and forth.

12347

[NQ6U]

Okay, someone explain the advantages (if any) of doing it this way. True, you don't have the B+ on the plate circuit but you still have the full potential somewhere else where you have to watch out for it, right?

[KC2UGV]

Okay, someone explain the advantages (if any) of doing it this way. True, you don't have the B+ on the plate circuit but you still have the full potential somewhere else where you have to watch out for it, right?

Someone like Kelli would have to chime in, but yes. And, in the case of a failed L1, you'd have it all over the chassis. I think.

[koØm]

Please excuse my interjection of opinion but, this whole thread seems to be some form of "Mental Masturbation" for the OP; that and he seems to be using the message board as his personal "Blow-up Party Doll"

Look at post #3 https://forums.hamisland.net/showthread.php/27559-Homebrew-Amps-Why-not-GROUND-the-B?p=587414&viewfull=1#post587414

now look at his post #90 https://forums.hamisland.net/showthread.php/27559-Homebrew-Amps-Why-not-GROUND-the-B/page9?p=591660#post591660

I guess that I should be proud.

.

[NQ6U]

Okay, I ran Kelli's schematic by my friend Gordon, AE6QW. He's got a PhD in physics and teaches a course called "Electronics for Scientists" at San Diego State University so he's a fairly knowledgeable source. His take on it is that, while the thing will work, it will take a very careful balancing act to make sure the voltage potential between the tube elements is set up correctly and, given the fact that components change in value over time, the thing will probably be somewhat unstable in the long term. He also pointed out that most of the components that are typically used under the chassis are not manufactured to handle plate voltages and that they would be more likely to fail, often catastrophically. He mentioned the filament transformer in particular in the case of a directly heated cathode, something a lot of high-gain RF amplifier tubes have.

When I asked him about possible advantages, about the only thing he could think of was being able to touch the plate connection while the thing was powered up—assuming, of course, that it wasn't producing any RF at the time. He mentioned that it does remove the possibility of having the B+ on the antenna in the event of a blocking capacitor failure but pointed out that should it fail on this design, you could end up with the high voltage on the input side instead, something which is far more dangerous.

I still have no personal dog in this fight, I'm just reporting back what I heard from Gordon.

[N2CHX]

Okay, I ran Kelli's schematic by my friend Gordon, AE6QW. He's got a PhD in physics and teaches a course called "Electronics for Scientists" and San Diego State University so he's a fairly knowledgeable source. His take on it is that, while the thing will work, it will take a very careful balancing act to make sure the voltage potential between the tube elements is set up correctly and, given the fact that components change in value over time, the thing will probably be somewhat unstable in the long term. He also pointed out that most of the components that are typically used under the chassis are not manufactured to handle plate voltages and that they would be more likely to fail, often catastrophically. He mentioned the filament transformer in particular in the case of a directly heated cathode, something a lot of high-gain RF amplifier tubes have.

When I asked him about possible advantages, about the only thing he could think of was being able to touch the plate connection while the thing was powered up—assuming, of course, that it wasn't producing any RF at the time. He mentioned that it does remove the possibility of having the B+ on the antenna in the event of a blocking capacitor failure but pointed out that should it fail on this design, you could end up with the high voltage on the input side instead, something which is far more dangerous.

I still have no personal dog in this fight, I'm just reporting back what I heard from Gordon.

Pretty much what I said from the start. Glad to hear it from another source. Thank you.

[KC2UGV]

Pretty much what I said from the start. Glad to hear it from another source. Thank you.

Honestly, I doubt many people were doubting your take on the design :)

[NQ6U]

Pretty much what I said from the start. Glad to hear it from another source. Thank you.

You're welcome. He also said something along the lines of "while you can do pretty much anything you want, some things are done a certain way out of long experience and changing that just for the sake of change often results in unexpected modes of failure."

[N2CHX]

You're welcome. He also said something along the lines of "while you can do pretty much anything you want, some things are done a certain way out of long experience and changing that just for the sake of change often results in unexpected modes of failure."

LOL exactly.

[W9JEF]

.


https://forums.hamisland.net/attachment.php?attachmentid=12347&d=1401205522

Nobody seems to realize that this grid will vaporize
with a potential of +5000 volts with respect to cathode.


As previously stipulated the grid should be connected to B minus,
and BYPASSED to ground (chassis) in this case make it .01 @10kV.

[NQ6U]

.


https://forums.hamisland.net/attachment.php?attachmentid=12347&d=1401205522

Nobody seems to realize that this grid will vaporize
with a potential of +5000 volts with respect to cathode.


As previously stipulated the grid should be connected to B minus,
and BYPASSED to ground (chassis) in this case make it .01 @10kV.

Okay, send me your schematic and I'll scan and post it here for further discussion.

[N2CHX]

Lulz

[KC2UGV]

.


https://forums.hamisland.net/attachment.php?attachmentid=12347&d=1401205522

Nobody seems to realize that this grid will vaporize
with a potential of +5000 volts with respect to cathode.


As previously stipulated the grid should be connected to B minus,
and BYPASSED to ground (chassis) in this case make it .01 @10kV.

You should post your schematic. It appears nothing anyone here is coming up with is what you're talking about. Even a broadcast engineer who has built and serviced a number of transmitters and other assorted gear, and a PhD. Both would be considered "experts" in this arena.

So, your words are failing to get your point across, so you'll have to break down, and draw a quick sketch. MSPaint works pretty good for that. Or, you can go here: http://www.digikey.com/schemeit

It should take less time than you usually spend posting here on the forum via your son's computer.

[KC2UGV]

Okay, send me your schematic and I'll scan and post it here for further discussion.

Or, draw one schematic, keep the original. Make 15 photo copies and send them to 15 people here who are willing to scan/post for you. This way ensures NOBODY will "muss it up".

[N2CHX]

Here you go. Modified as per what he said. Not sure why I'm doing his homework for him, but... 12349

[N2CHX]

I don't see how this is going to ever work, however. Either the filament transformer would have to be floated off of ground completely or the tube would have to withstand several thousand volts (supply voltage) between the cathode and filament. Good luck with that. Makes a hella lot more sense to just put the supply in the plate side where it belongs.

[W9JEF]

I don't see how this is going to ever work, however. Either the filament transformer would have to be floated off of ground completely or the tube would have to withstand several thousand volts (supply voltage) between the cathode and filament. Good luck with that. Makes a hella lot more sense to just put the supply in the plate side where it belongs.

You're right about the filament transformer, Kelli
(without sufficient cathode-to-filament insulation).
With my 811-A amp, the filament is the cathode.
The big old 20 amp transformer from Fair Radio Sales
has impressive insulators on the secondary connections,
so I (correctly) assumed it could take the 1400 volts.

https://forums.hamisland.net/attachment.php?attachmentid=12349&d=1401274263

Thanks for your help--neat work--on the right path. :)
Your C1 bypasses the B-minus which is a good thing.
The grid connection needs to be ungrounded,
and connected directly to B-minus, and let C1
be its "ground" (for RF purposes).

For a 50 ohm output, we need a pi-network
(input and output tuning capacitors to ground,
with the tank coil between them).
The DC plate current path is through
an RF choke from output to ground.

[W9JEF]

You should post your schematic. It appears nothing anyone here is coming up with is what you're talking about. Even a broadcast engineer who has built and serviced a number of transmitters and other assorted gear, and a PhD. Both would be considered "experts" in this arena.

So, your words are failing to get your point across, so you'll have to break down, and draw a quick sketch. MSPaint works pretty good for that. Or, you can go here: http://www.digikey.com/schemeit

It should take less time than you usually spend posting here on the forum via your son's computer.

Went to the digikey site, and managed to get a
triode pasted, but no luck with going further.
Like I said, I'm a klutz when it comes to things digital-
-one reason I retired early from BC engineering.

Need to do some dishes and get other things done.

Have a good day. :)

73,

Jim

[N2CHX]

OK, I was half asleep and in a hurry to get ready for work when I drew the last one...

This is probably closer to what you're talking about...

12352

[N2CHX]

12353

Added filament transformer. Tube is integreted filament/cathode type. Ideally there should be chokes in there as well.

[N2NH]

Oh second thought...

No.

[W9JEF]

12353

Added filament transformer. Tube is integreted filament/cathode type. Ideally there should be chokes in there as well.

Good work, Kelli! :)

Most HF ham radio amps use a bifilar filament choke on a ferrite core.

And, of course a pi-section tank circuit to match the plate impedance

to the antenna (or intermediate tuner). Tuning capacitor from plate to ground,

break the connection from L1 to ground, and insert the loading capacitor;

there's your output--with an RF choke to ground, to complete the DC path.

[kb2vxa]

Now why with all your expertise couldn't YOU do that?

Heh heh heh...

[W9JEF]

Now why with all your expertise couldn't YOU do that?

Heh heh heh...

I did it with WORDS. ;)

[n2ize]

Okay, someone explain the advantages (if any) of doing it this way. True, you don't have the B+ on the plate circuit but you still have the full potential somewhere else where you have to watch out for it, right?

All my old tube rigs have high B+ on the plates. And I've been running them for decades. And I am still alive to talk about it. You see the simple solution is that when you need to stick your fingers inside to work in and around the B+ you first shut off the transmitter. Then you disconnect it from the mains. Then you open the cabinet and make sure the power supplies are discharged, you can use a shorting stick or a bleeder resistor. Once everything is at zero potential you can now reach inside and safely work on the thing without killing yourself. I can safely touch the plate cap of a tube that just a couple minutes before had several thousands of volts on it. I've been doing it that way for decades and it seems to work.

[n2ize]

I did it with WORDS. ;)

No it was done with a picture (schematic) that Kelli took the time to draw using some of your words and her expertise in broadcast radio circuits to draw the circuit that she feels is closest to what you were attempting to describe with only words.. Once she did this everyone else was able to get a clearer picture of what is happening. Even those who have little experience with tubes. So if anyone deserved credit it is Kelli for providing a schematic. Yet, apparently you say that Kelli's diagram still doesn't describe it right. So if you cannot describe it with words and you cannot/will not under any circumstance provide a schematic I call BS. Or else you don't understand it yourself. After all, if you can't explain it with words and pictures then you don't understand it.

[W9JEF]

No it was done with a picture (schematic) that Kelli took the time to draw using some of your words and her expertise in broadcast radio circuits to draw the circuit that you were attempting to describe with only words.. Once she did this everyone else was able to get a clearer picture of what is happening. Even those who have little experience with tubes. So if anyone deserved credit it is Kelli for providing a schematic.

Kelli certainly deserves credit for providing a schematic for those who
could not comprehend the words I used to describe a very simple circuit.

[W9JEF]

No it was done with a picture (schematic) that Kelli took the time to draw using some of your words and her expertise in broadcast radio circuits to draw the circuit that she feels is closest to what you were attempting to describe with only words.. Once she did this everyone else was able to get a clearer picture of what is happening. Even those who have little experience with tubes. So if anyone deserved credit it is Kelli for providing a schematic. Yet, apparently you say that Kelli's diagram still doesn't describe it right. So if you cannot describe it with words and you cannot/will not under any circumstance provide a schematic I call BS. Or else you don't understand it yourself. After all, if you can't explain it with words and pictures then you don't understand it.

Read the Stephen Hawking quote again: It's words OR pictures.

The extra measure of safety of all lethal voltage being
under the chassis and out of reach is frosting on the cake.

Those familiar with the design of multi-band HF tube RF power amplifiers will
recognize the advantage of having no RF choke shunting the high impedance plate.
Eliminating the plate blocking capacitor and its inductive reactance at VHF
simplifies the suppression of destructive TGTP parasitic oscillations.

[n2ize]

Kelli certainly deserves credit for providing a schematic for those who
could not comprehend the words I used to describe a very simple circuit.

You mean the circuit you don't understand. If you understood it you would have been able to explain it. Just for the record I even had a 7 year old (my sisters kid) read your words and he couldn't understand it. So obviously you don't understand it.

[W9JEF]

You mean the circuit you don't understand. If you understood it you would have been able to explain it. Just for the record I even had a 7 year old (my sisters kid) read your words and he couldn't understand it. So obviously you don't understand it.


Your argument is with Stephen Hawking and Albert Einstein.
Those are their words, but, of course they aren't as smart as you are. ;)

This is supposedly a ham radio technical forum.
What's the need to explain a circuit on the
understanding level of a six or seven year old?

[KC2UGV]

Your argument is with Stephen Hawking and Albert Einstein.
Those are their words, but, of course they aren't as smart as you are. ;)

This is supposedly a ham radio technical forum.
What's the need to explain a circuit on the
understanding level of a six or seven year old?

Perhaps it's because your design specifications kept changing. Kelli needed THREE iterations to get what you were saying, and you had changes for each one.

Now, perhaps, you can mail the schematic for YOUR amplifier that you are currently using, instead of the conceptual design we have here?

[n2ize]

Read the Stephen Hawking quote again: It's words OR pictures.

Yeah, its words OR pictures. So, since your words have failed to properly convey your idea (even to a 7 year old) ,AND even when spoken to a person with decades of experience in broadcast engineering and who knows more about the subject than I do it would make things clearer if you could simply draw a schematic so we can get a better idea of why this is a good way of doing things and what, if anything can go wrong. I have an idea of what you are saying but a schematic would make it clearer. Unfortunately every time we asked for a schematic you have come up with an excuse. Everything from not being able to figure out how to draw on digitally or scan it, to claiming that others would spitefully muck it up if you mailed them a copy.



The extra measure of safety of all lethal voltage being
under the chassis and out of reach is frosting on the cake.


It may be a slight measure of safety but I have never had a problem with lethal voltage on top of the chassis. By the use of common precautions when working on high voltage equipment, namely shutting the equipment down, disconnecting it from the main lines, and making sure everything is discharged before I touch anything up top. And it has worked for me. And from what I understand with your idea lethal voltage would still be present bottom side of the chassis and frequently when i work on high voltage equipment I end up having to reach into the bottom of the chassis. So my three steps... shut down,,, disconnect...discharge ... also keep me safe when i am down on the bottom of the chassis as well. Again , a schematic would help a great deal in enabling a better understanding of the advantages of your circuit ad what, if anything may go wrong.



Those familiar with the design of multi-band HF tube RF power amplifiers will
recognize the advantage of having no RF choke shunting the high impedance plate.
Eliminating the plate blocking capacitor and its inductive reactance at VHF
simplifies the suppression of destructive TGTP parasitic oscillations.

Again, what you say may be true but a schematic would make it clearer.

Another option would be to do what a lot of guys have been doing for a while now on the AM side.Abandon tubes altogether and go completely class E solid state. Clean, efficient, state of the art, relatively inexpensive (power tubes are not cheap these days), and working at much lower voltages. Plus, if a power MOSFET goes bad you are still on the air, albeit some loss of power. Plus, they have made lots of schematics available with steb by step instructions. Even a 6 year old could (almost) build one.

[W9JEF]

Perhaps it's because your design specifications kept changing. Kelli needed THREE iterations to get what you were saying, and you had changes for each one.

Now, perhaps, you can mail the schematic for YOUR amplifier that you are currently using, instead of the conceptual design we have here?

Anyone with basic RF tube power amp savvy can plainly see there were no changes--just clarifications.

[K7SGJ]

12359

[n2ize]

Perhaps it's because your design specifications kept changing. Kelli needed THREE iterations to get what you were saying, and you had changes for each one.

Now, perhaps, you can mail the schematic for YOUR amplifier that you are currently using, instead of the conceptual design we have here?

Don't hold your breath. In fact, Forget it. It will never happen. Rest assured you won't be getting any schematic in the mail.

[n2ize]

Your argument is with Stephen Hawking and Albert Einstein.
Those are their words, but, of course they aren't as smart as you are. ;)


That's an appeal to authority. There is no doubt that Einstein and Hawking are very smart men. But that doesn't mean every thought or idea or everything they say is necessarily correct. Very often when people are trying to make a point they will cite a well known scholar and say, "well it must be right because he said so.". But that is not the case. That is why we have something called peer review. Freeman Dyson is a brilliant mathematician and physicist. Yet he is also a global warming denier. Despite his brilliance in Physics and math his arguments about climate change are dead wrong and would never pass peer review. Yet people will often appeal to authority and cite him and say, "well if Freeman disagrees with climate change then there must be no climate change". Just because a person may be famous and smart doesn't mean every thought they think or words they utter are true.



This is supposedly a ham radio technical forum.
What's the need to explain a circuit on the
understanding level of a six or seven year old?

Because you say that if you can't explain something to a six year old you don't understand it. So i asked a 7 year old to read it (7 is one year older than 6) and he didn't understand it. So then that must mean you don't understand it. Right ? Or does that only apply to 6 year old's so, a year ago he would have understood it ?

[W9JEF]

Yeah, its words OR pictures. So, since your words have failed to properly convey your idea (even to a 7 year old) ,AND even when spoken to a person with decades of experience in broadcast engineering and who knows more about the subject than I do it would make things clearer if you could simply draw a schematic so we can get a better idea of why this is a good way of doing things and what, if anything can go wrong. I have an idea of what you are saying but a schematic would make it clearer. Unfortunately every time we asked for a schematic you have come up with an excuse. Everything from not being able to figure out how to draw on digitally or scan it, to claiming that others would spitefully muck it up if you mailed them a copy.

I'm quite content with Kelli's final draft of the schematic.
Appreciate her taking time away from her family
to do what this OT wishes he had the time to do himself.

In fact;

. . . . . . . . . DISCLAIMER:

"If, based on my posts and Keli's schematic,
if you cannot now design and construct
your own grounded B+ tube amp,
then do not attempt without guidance
from someone who can"




It may be a slight measure of safety but I have never had a problem with lethal voltage on top of the chassis. By the use of common precautions when working on high voltage equipment, namely shutting the equipment down, disconnecting it from the main lines, and making sure everything is discharged before I touch anything up top. And it has worked for me. And from what I understand with your idea lethal voltage would still be present bottom side of the chassis and frequently when i work on high voltage equipment I end up having to reach into the bottom of the chassis. So my three steps... shut down,,, disconnect...discharge ... also keep me safe when i am down on the bottom of the chassis as well. Again , a schematic would help a great deal in enabling a better understanding of the advantages of your circuit ad what, if anything may go wrong.

You never heard of anyone being electrocuted by his RF power amp?
Even if a grounded B+ saves one life, it will be worth it.
Having no exposed high voltage topside--no need to go through
the safety "manual of arms" each time you tweak something.




Again, what you say may be true but a schematic would make it clearer.

The basic concept couldn't be clearer to those who would be building a tube amp.
My original schematic is in pencil, and has not been updated since 2008.
There were some minor changes, some of the relays aren't clearly marked,
and much of the faded pencil is not a diagram--just notes.
Minor details of this sketchy schematic may or may not
have made the final cut. (All I know is that if it ain't broke...) :)



Another option would be to do what a lot of guys have been doing for a while now on the AM side.Abandon tubes altogether and go completely class E solid state. Clean, efficient, state of the art, relatively inexpensive (power tubes are not cheap these days), and working at much lower voltages. Plus, if a power MOSFET goes bad you are still on the air, albeit some loss of power. Plus, they have made lots of schematics available with steb by step instructions. Even a 6 year old could (almost) build one.

Oh, yeah, I could probably have broken the Christmas Island pileup on 160 CW
sooner if I had 1500 instead of 500 watts. A solid state amp is not in the budget.

Originally the 811-A's were surplus, and failed within the year,
so got new ones for about $20 a piece. Not expensive at all
when you consider their forgiveness of accidental overload.
The chassis was a tube-type regulated DC supply, a gift.
Stripped all (including krinkly panel paint)
but the high voltage power transformer. Other parts
from junk box, or bought at bargain prices.
It loads fine into my below 50 ohm cage 160 meter umbrella vertical.
Tubes and tuning controls make the match--no tuner needed. :)
Ah, the glow of the tubes on a cold winter pre-dawn morning.
Top is open for good ventilation with no fans,
and so what, if I drop a screwdriver in it? :yes:

[W9JEF]

That's an appeal to authority. There is no doubt that Einstein and Hawking are very smart men. But that doesn't mean every thought or idea or everything they say is necessarily correct. Very often when people are trying to make a point they will cite a well known scholar and say, "well it must be right because he said so.". But that is not the case. That is why we have something called peer review. Freeman Dyson is a brilliant mathematician and physicist. Yet he is also a global warming denier. Despite his brilliance in Physics and math his arguments about climate change are dead wrong and would never pass peer review. Yet people will often appeal to authority and cite him and say, "well if Freeman disagrees with climate change then there must be no climate change". Just because a person may be famous and smart doesn't mean every thought they think or words they utter are true.

It doesn't mean their quotes are false, either.

They appear in my sig because I agree.

Freeman Dyson??? Red herring, and straw man. :lol:




Because you say that if you can't explain something to a six year old you don't understand it. So i asked a 7 year old to read it (7 is one year older than 6) and he didn't understand it. So then that must mean you don't understand it. Right ? Or does that only apply to 6 year old's so, a year ago he would have understood it ?

I have had no contact with your 7 year old.

And I've neither the need nor time to prove I could explain.
In the case of high voltage circuits--above or below deck:
I would only explain that a 7-year-old... STAY AWAY

You have very little understanding of tube technology,
so you're reduced to yapping at the heels of my sig.

This virtual stalking gets old after a while, OM. :sick:

[NA4BH]

JEF, let's settle this. Send me the schematic, I couldn't read one if you held a gun to my head. I wouldn't know how to change it to the good or bad to help/destroy your case. I will scan it and post it. Today's the 29th, you have until the 1st of June to send it to me. If it is not here by midnight on the 31st of May, you are full of _____ (fill in the blank). Case closed. OK?

[W9JEF]

Don't hold your breath. In fact, Forget it. It will never happen. Rest assured you won't be getting any schematic in the mail.

A complete schematic???

Maybe it will appear in my book..;)

Thanks to Kelli, the basic concept and diagram is now clear

for anyone who should be building amps in the first place.

No offense.

[W9JEF]

JEF, let's settle this. Send me the schematic, I couldn't read one if you held a gun to my head. I wouldn't know how to change it to the good or bad to help/destroy your case. I will scan it and post it. Today's the 29th, you have until the 1st of June to send it to me. If it is not here by midnight on the 31st of May, you are full of _____ (fill in the blank). Case closed. OK?

A deal I can't refuse!!!

Well, I may be seen as full of it, but what matters to me is, that it works. :)

Not a complete diagram, but I will show special bias and control circuits needed.

Anyone who builds knows power supplies, control circuits and such.

I'll never make it by the 31'st, so I respectfully request a week's extension. :)

[NA4BH]

6pm on the first is your extension. Think of the extension as a gift, not a loan. Quit typing and get drawing. Capiche?

[NA4BH]

And that's 6pm Central, 7pm Eastern, 4pm Pacific, and 5pm in that time zone that really doesn't exist.

[NQ6U]

5pm in that time zone that really doesn't exist.

It's the time zone that's full of desert rats.

[NA4BH]

It's the time zone that's full of desert rats.

They really don't exist. Bushtit, I wish I could say more.

[NQ6U]

They really don't exist. Bushtit, I wish I could say more.

Nothing more need be said.

[W9JEF]

.


I was going to start a thread on my 80 meter turnstile fed with

4-wire open line, but y'all would likely call bushtit on that, too. :irked: :)

[W9JEF]

6pm on the first is your extension. Think of the extension as a gift, not a loan. Quit typing and get drawing. Capiche?

I wish I could fly with the birds; as the USPS would never get it there on time.

Rev up the DC-3, fly to XNA, and I can drop it there.

You might want to wait 'til August, when Cheech and Chong play at the Walm*rt Amp.

[NA4BH]

I got a feeling that 6pm Sunday will be known from here on out as the "BULLSHIT" Hour. Shouldn't you be drawing and not posting?

[NA4BH]

I wish I could fly with the birds; as the USPS would never get it there on time.

Rev up the DC-3, fly to XNA, and I can drop it there.

You might want to wait 'til August, when Cheech and Chong play at the Walm*rt Amp.

So an early bullshit can be called?

[W9JEF]

I got a feeling that 6pm Sunday will be known from here on out as the "BULLSHIT" Hour. Shouldn't you be drawing and not posting?

At 6pm Sunday, if there's nothing really interesting on 60 Minutes,
my grounded B+ amp could be getting RST 599 in Europe or South Africa.

I'll put a little sticky on the panel to remind me of its organic status on the Island. ;)

[W9JEF]

So an early bullshit can be called?


Calling bullsh*t on my grounded B+ amp, to me,
underscores its uniqueness and genius of design. :yes:

[NA4BH]

If you could only know how much I stood up for you via the emails and PM's I received.

[NA4BH]

https://www.youtube.com/watch?v=cRhOf9evcps

[WØTKX]

http://static.fjcdn.com/pictures/Bazinga_ab6222_965049.jpg

[NA4BH]

Bushtit

[K7SGJ]

Say no more.

[NA4BH]

No more will be said

[K7SGJ]

You've said it all.

[NA4BH]

Like the amp, indulge me here:

I graduated Magna Cum Laude and got two B+'s. One where the teacher thought I was somebody else and the other was actually earned because the teacher was trying to hit on the females in the radiation pathology class (I wouldn't put out and I'm not female). So here i sit second in my class. This proves B+ doesn't work.

[n2ize]

It doesn't mean their quotes are false, either.

They appear in my sig because I agree.

Freeman Dyson??? Red herring, and straw man. :lol:


The point is that just because you agree with someone and just because the person you agree with has credentials that make him or her an authority on something doesn't make the claim valid. I brought up Freeman Dyson as an example because a lot of climate change deniers quote him to support their claim that climate change (aka global warming) is a myth. You agree that words or pictures are enough to explain something and that if you can;t explain it to a six year old you don;t understand it. Since your words were not able to explain clearly it to a 7 year old, nor to a broadcast engineer, nor to many of us who have had a great deal of experience itself then it is an indication that a picture (i.e. schematic) might be a good idea. But you keep coming up with excuses as to why you can't provide one, even to the point of claiming we would deliberately alter it to make you wrong.




I have had no contact with your 7 year old.



And I've neither the need nor time to prove I could explain.
In the case of high voltage circuits--above or below deck:
I would only explain that a 7-year-old... STAY AWAY


Yet another excuse.



You have very little understanding of tube technology,
so you're reduced to yapping at the heels of my sig.


Actually I grew up with tube technology, I still use it extensively, all my HF rigs are 100% tube technology. I have scratch built several tube circuits.I may not understand it as well as you or Kelli being that I was not a Bcast engineer (although I have had the opportunity to work with a Bcast engineer and read the schematics of both tube and solid state bcast transmitters as well as work inside the cabinets) . But your words describing your tube circuit have me (and apparently others) a bit curious and confused which is why it would be helpful if you could provide a schematic. Like the old bromide goes, "A picture is worth 1000 words". Add that to your list of footnotes.


This virtual stalking gets old after a while, OM. :sick:

Now comes the victim call. Nobody is stalking you, we re asking you you provide the schematic... You said you would provide one but then you backpedaled. I am not going to discuss this with you any further until I see your schematic.. Until then I am going to go by Kelli's schematic. My assessment based on Kelli's schematic is that your idea has some merits, namely that you can contact the plate connection while it is powered up, which is something I wouldn't do regardless of whether the B+ is grounded or not. At the same time it also has some disadvantages and potential risks. No further comments until I see your schematic.

[n2ize]

You never heard of anyone being electrocuted by his RF power amp?


Yes. Most of the time it was due to not following proper safety guidelines.

1) Shut power
2) Disconnect from mains
3) Discharge supplies, make sure they are at zero potential.
4) Proceed to do the work.



Even if a grounded B+ saves one life, it will be worth it.
Having no exposed high voltage topside--no need to go through
the safety "manual of arms" each time you tweak something.

Even if the B+ is grounded I am still not going to stick my hands in there without taking the proper safety steps. I am going to go through the "manual of arms" regardless of whether the B+ is grounded or whether its not. It may take longer for me to make an adjustment. But I am still not going to take chances. If it takes me longer to tweak an adjustment then so be it.

[n2ize]

Like the amp, indulge me here:

I graduated Magna Cum Laude and got two B+'s. One where the teacher thought I was somebody else and the other was actually earned because the teacher was trying to hit on the females in the radiation pathology class (I wouldn't put out and I'm not female). So here i sit second in my class. This proves B+ doesn't work.

Sounds like the teacher had negative bias.

[N2CHX]

Dafuq happened in here last night? Wow.

[KC2UGV]

So, back to your schematic, Kelli: Since the hot side of the power supply is connected to ground, what would ground be connected to?

It might be my caveman sysadmin brain, but it would appear that the chassis is considered ground, your chassis would be at xV, which in and of itself would be an inherent safety issue with the design, since anyone touching the chassis would be (Hypothetically) at 0V potential, and therefore at risk.

Whereas, if you were to use 0V as ground (Which is, from what I gather, standard design for amps and other electronic equipment), touching the case should be no issue, since you and the case are at 0V potential.

Like I said, maybe I'm stupid, because you already tried to explain it to me, and I don't get it.

[kb2vxa]

"I graduated Magna Cum Laude and got two B+'s."
A Magna Cum Soft won't go in I suppose.

"This proves B+ doesn't work."
In a circuit with B- it sure won't!

"Sounds like the teacher had negative bias."
Class C?

"Dafuq happened in here last night?"
Late at night while you're sleepin' Poison Ivy comes a'creepin' around...........

JEF make you bumpy
But da hamma made him lumpy
And high B+ make him jump and twitch
He thought he could fool ya
That B- could cool ya
But moderation is a bitch!

[n2ize]

Dafuq happened in here last night? Wow.

We are expecting Bushtit hour to arrive when the schematic doesn't arrive. :snicker::lol:

[n2ize]

So, back to your schematic, Kelli: Since the hot side of the power supply is connected to ground, what would ground be connected to?

It might be my caveman sysadmin brain, but it would appear that the chassis is considered ground, your chassis would be at xV, which in and of itself would be an inherent safety issue with the design, since anyone touching the chassis would be (Hypothetically) at 0V potential, and therefore at risk.

Whereas, if you were to use 0V as ground (Which is, from what I gather, standard design for amps and other electronic equipment), touching the case should be no issue, since you and the case are at 0V potential.

Like I said, maybe I'm stupid, because you already tried to explain it to me, and I don't get it.

Look at a standard tube rf amp and you'll see it is basically the reverse of Kelli's diagram. Normally the - side of the supply is grounded and the B+ applied to the tube is measured relative to ground. This is basically the reverse. The + side is grounded and the negative bias is tied to the cathode and the plate is connected to ground. Thus the tube see's the same potential between the cathode and the plate. But the chassis is not at +5000V potential and more than it would be at -5000V if the amp was constructed the standard way. Look up a diagram of a standard amp with B+ applied to the plates and the cathode is tied to ground. When you compare them I think you'll get a clear picture of what is going on

The only advantage to this design is it keeps the high DC voltage B+ off the plates of the finals (and I suppose the modulators as well depending on how the tubes are connected). Since most hams tend to approach the top of the chassis more often instead of the bottom they are less likely to get a lethal shock if they should touch the plate connections while the amp or transmitter is on being the tubes and plate caps are usually mounted topside. All bets are off if you are going to stick your fingers under the chassis while it is on.

Of course all this is unessesary if you follow the standard safety procedure BEFORE you touch anything inside the cabinet

1) Turn off the transmitter.
2) Disconnect it from the mains.
3) Discharge the power supplies completely to make sure the condensers are not still holding a charge.

In other words don't put your hands inside the cabinet at any time while the circuits are live regardless of whether the circuit is of grounded B+ design or not. Touching anything inside the cabinet where high potentials exist is dumb and dangerous regardless of how the circuit is designed.

[N2CHX]

So, back to your schematic, Kelli: Since the hot side of the power supply is connected to ground, what would ground be connected to?

It might be my caveman sysadmin brain, but it would appear that the chassis is considered ground, your chassis would be at xV, which in and of itself would be an inherent safety issue with the design, since anyone touching the chassis would be (Hypothetically) at 0V potential, and therefore at risk.

Whereas, if you were to use 0V as ground (Which is, from what I gather, standard design for amps and other electronic equipment), touching the case should be no issue, since you and the case are at 0V potential.

Like I said, maybe I'm stupid, because you already tried to explain it to me, and I don't get it.

The path is completed through the choke on the plate connected to ground. There is no inherent danger in this in regard to ground. It's simply a negative supply, really no different than a +/- bench test supply except the voltage. Think of it as the negative half of an AC waveform.

[N2CHX]

Here's the same circuit, but in a Class C configuration like you'd find in an FM broadcast transmitter, less the bias and tuning details. In an FM transmitter the tuning inductor is usually a sliding metal bar or rod that changes length and the loading is an open-air variable capacitor between the plate and RF output. Lots of details left out here, as we're mainly interested in the basic flow of supply voltage and RF.

12369

[n2ize]

Here's the same circuit, but in a Class C configuration like you'd find in an FM broadcast transmitter, less the bias and tuning details. In an FM transmitter the tuning inductor is usually a sliding metal bar or rod that changes length and the loading is an open-air variable capacitor between the plate and RF output. Lots of details left out here, as we're mainly interested in the basic flow of supply voltage and RF.

12369

So it seems I am correct. The diagram above (with some variation) is what I am familiar with on most of my old plate modulated rigs The grounded B+ amp is basically the reverse of this. In both cases (traditional or grounded B+) the tube operates because it still see's the same potential but in the case of the grounded B+ circuit touching the plate supply (i.e. the plate cap on the tube) would be like touching the chassis or cabinet, i.e. no electrocution. But there is still a shock hazard if you touch the cathode end of the grounded B+ amp (am I right ?).

In any event regardless of the circuit, grounded B+ or not, I am still not going to stick my hand in the cabinet when the transmitter is energized. I am still going to follow the basic safety steps (i.e. shut down, disconnect, discharge) before I work inside.

[N2CHX]

So it seems I am correct. The diagram above (with some variation) is what I am familiar with on most of my old plate modulated rigs The grounded B+ amp is basically the reverse of this. The tube operates because it still see's the same potential but in the case of the grounded B+ circuit touching the plate supply (i.e. the plate cap on the tube) would be like touching the chassis or cabinet, i.e. no electrocution. But there is still a shock hazard if you touch the cathode end of the grounded B+ amp (am I right ?).

Correct.


In any event regardless of the circuit, grounded B+ or not, I am still not going to stick my hand in the cabinet when the transmitter is energized. I am still going to follow the basic safety steps (i.e. shut down, disconnect, discharge) before I work inside.

Smart man. Anyone who intentionally sticks their hand into a cabinet with high voltage is an idiot. I've seen what 4 kV plate voltage does to someone first-hand, while working on an old McMartin 2.5 kW transmitter. Long story but in a nutshell; A guy assisting me reached into the cabinet while holding down the interlock switch of the meter panel, so I could get some readings with a DMM. The DMM fell into the cabinet, and instinctively, he reached in to grab it and got tangled in the plate voltage. Sent him flying into a plate-glass window overlooking the studio from the transmitter room. I will never, ever forget that. It was early in my career and I almost quit because of it. My boss convinced me to keep at it and not quit or I would have. I cried my eyes out as they wheeled poor Glen out on a stretcher. He had the imprint of my multimeter burned into his hand and he was shaking like he was having a seizure. Glen wasn't an idiot, he was a good, smart guy. He just wasn't tech savvy and I wasn't fast enough to stop him.

[koØm]

Correct.



Smart man. Anyone who intentionally sticks their hand into a cabinet with high voltage is an idiot. I've seen what 4 kV plate voltage does to someone first-hand, while working on an old McMartin 2.5 kW transmitter. Long story but in a nutshell; A guy assisting me reached into the cabinet while holding down the interlock switch of the meter panel, so I could get some readings with a DMM. The DMM fell into the cabinet, and instinctively, he reached in to grab it and got tangled in the plate voltage. Sent him flying into a plate-glass window overlooking the studio from the transmitter room. I will never, ever forget that. It was early in my career and I almost quit because of it. My boss convinced me to keep at it and not quit or I would have. I cried my eyes out as they wheeled poor Glen out on a stretcher. He had the imprint of my multimeter burned into his hand and he was shaking like he was having a seizure. Glen wasn't an idiot, he was a good, smart guy. He just wasn't tech savvy and I wasn't fast enough to stop him.

Did he come back to that job, did he stay in the field?

.

[n2ize]

Correct.


Okay. Got it...



Smart man. Anyone who intentionally sticks their hand into a cabinet with high voltage is an idiot. I've seen what 4 kV plate voltage does to someone first-hand, while working on an old McMartin 2.5 kW transmitter. Long story but in a nutshell; A guy assisting me reached into the cabinet while holding down the interlock switch of the meter panel, so I could get some readings with a DMM. The DMM fell into the cabinet, and instinctively, he reached in to grab it and got tangled in the plate voltage. Sent him flying into a plate-glass window overlooking the studio from the transmitter room. I will never, ever forget that. It was early in my career and I almost quit because of it. My boss convinced me to keep at it and not quit or I would have. I cried my eyes out as they wheeled poor Glen out on a stretcher. He had the imprint of my multimeter burned into his hand and he was shaking like he was having a seizure. Glen wasn't an idiot, he was a good, smart guy. He just wasn't tech savvy and I wasn't fast enough to stop him.
[/quote]

Yikes... That sounds horrific. I hope he eventually recovered and was Ok afterwards ? I also learned my lesson the hard way. I was working in the bottom chassis of a transmitter. I think I was adjusting the sliding tap on a large wirewound resistor and after each adjustment I would flick on the high voltage B+ supply and check readings. I started to get careless and at one point with the plates on and one hand on the chassis my other hand hit something hot and It went right through my chest (probably through my heart as well) , my eyes went blank, blew me across the room, left a burn on my hand (i could smell burning flesh),a strong metallic taste in my mouth and my arms and shoulders ached. Luckily I recovered quickly. It was then and there that I decided that I will never ever again work on any equipment like that until it is shut down, disconnected, and discharged. Even if it takes longer to get something tweaked right, even though I have to go through those steps each time I make even a slight adjustment it is far better than getting electrocuted. Even when I think about that incident it gives me chills and I can still remember and sense the feel of the sudden pain I experienced. To this date I will not reach inside energized equipment no matter what the circuit design and no matter how safe or foolproof anyone claims it may be. Your life is not worth the risk of working on energized equipment no matter how much time it might seem to save.

[kb2vxa]

Oh man are you old school, a CONDENSER? I don't know where they got that one from; it doesn't condense electrons, but it has the capacity to store charge, hence the capacitor. Speak about learning the hard way, once upon a time I did something incredibly stupid and got 600VDC from my hand to my elbow. I got stuck and couldn't turn it off, it took a minute or so for a friend responding to my screams to throw the kill switch on the wall. The room smelled like BBQ, my hand was burnt, and it took weeks to regain full use of my arm. Later while servicing a color TV I learned about capacitive hysteresis the hard way when I thought the A2 of the picture tube was OK after discharging it 10 minutes before. The next thing I remember was flat on my back with tweety birds circling my head. Considering all the electrons I've absorbed in the course of time I have a high enough charge to kill and lightning is afraid of ME.

Then there is working inside the cabinet. When it's a broadcast transmitter you work INSIDE the cabinet. It's too funny to forget helping an engineer too fat to get inside an AM transmitter, I did all the major work, and to get rid of the sound of bacon frying in the audio I removed the tubes, disconnected the modulator deck, and put it on the bench. There he changed all the resistors and capacitors dating from 1950 and got rid of the sky wiring left by the last engineer, then I put it all back together again. There are three important safety features beginning with the door interlock switches, NEVER DEFEAT THEM. Then there is the mains disconnect, if it's the plug type (for lack of a better term) remove the plug and hide it in a place only you know so some idiot doesn't come along and replace it when you're not looking. If it's the switch type, pull the lever down, lock it, and put the key in your pocket. Last is the Jesus stick, USE IT, they don't call it a Jesus stick for nothing! It's better seeing to it the transmitter is dead than the transmitter seeing to it YOU'RE dead! I do believe Kelli will agree wholeheartedly when it comes to SAFETY FIRST, because if you don't it will be your LAST.

Oh, when they were casting for the movie somebody must have told them about my condition and I got the part. All they needed was wardrobe and makeup, I did the special effects myself.

[n2ize]

Oh man are you old school, a CONDENSER? I don't know where they got that one from; it doesn't condense electrons, but it has the capacity to store charge, hence the capacitor.

My first exposure to tube circuits and literature explaining how and why they work came via an old timer. He was from Europe and was working as an engineer for Zenith way back in the early days of radio sets. He later began designing TV's for them just before he retired. He always called them "condensers". The term just stuck with me from there on. Besides when said in these modern times it sounds very retro, and I kind of like that. I am a very retro kind of person.

P.S. In writing if I do use the word "condensers" I guess I should make clear I am referring to capacitors as many new schoolers have never heard the term.

[N2NH]

"Sounds like the teacher had negative bias."
Class C?

No Class.

[NQ6U]

No Class.

In Soviet Union, we live in classless society, Tovarisch.

[n2ize]

Class E !!!!!!

[K7SGJ]

In Soviet Union, we live in classless society, Tovarisch.

Dah.

Bushtitski

[W2NAP]

In Soviet Union, we live in classless society, Tovarisch.

In soviet russia B+ grounds you!

[n2ize]

Soviet Russia... the biggest scam ever imposed upon the world.

[NY4Q]

I did it with WORDS. ;)

http://en.wikipedia.org/wiki/A_picture_is_worth_a_thousand_words

And thank you, no. I prefer "the other" way.

[KC2UGV]

The path is completed through the choke on the plate connected to ground. There is no inherent danger in this in regard to ground. It's simply a negative supply, really no different than a +/- bench test supply except the voltage. Think of it as the negative half of an AC waveform.

So, thats where I was confused. The power supply is a negative supply, ie -X volts. Thanks.

[n2ize]

Well, seems the deadline has passed and no schematic. :snicker:

[WØTKX]

B-Man the aniti-hero will be back, of course.

See my new sigline. :mrgreen:

[n2ize]

B-Man the aniti-hero will be back, of course.

See my new sigline. :mrgreen:

LOL... Coming next. At an Island near you !!!

[W9JEF]

If you could only know how much I stood up for you via the emails and PM's I received.


If I only knew the reason I got banned for a week--and by whom. (???)

I'm all ears...

[koØm]

If I only knew the reason I got banned for a week--and by whom. (???)

I'm all ears...

A word to the wise should be sufficient! Respectfully station, your personal situation is something that should be discussed with the Admins or Moderator via PM's and not on the open message board. Are you cruising for another bruising?

.

[ad4mg]

If I only knew the reason I got banned for a week--and by whom. (???)

I'm all ears...

OK, ears. After repeated warnings about posting political comments in any forum besides the political forum, you continued to do just that. Your standard issue "my bad" response to repeated warnings had worn thin. Bob actually pulled the trigger, but I can assure you he beat me to it by only minutes.

We have a forum (The Forbidden Zone - mainly political topics) that is about as wide open as it can be and still maintain some semblance of civility, so we are VERY serious about there being NO POLITICS in the other forums. Also, the technical forums are for just that, technical discussions, hence the long overdue lock on this piece of garbage.

Our regular members know this, and we are very consistent. We will issue multiple warnings, then, if we are forced to use the clue-by-four, a one week vacation will be imposed. You just enjoyed one of those.

A repeat will bring the offender a two week vacation. Cross that particular line again, and it's a called third strike, game, set, and match.

I'm very hopeful that you have received and understood this message. Now, let me drag a padlock out of the storage chest...