Amplifier

[kk4fpx]

I'm posting this on CB because I bought a Palamar TX-150 amp to use on 10 meters.They were meant for CB.I can't find a user manual for it.
Anyone know anything about this amp?

[KA9MOT]

I know enough about it to tell you that it is garbage. This amp is not suitable to be used on 10M unless you have allot of skill building amplifiers... and it won't be easy to clean it up.

[KG4CGC]

Tap the coil by 1 loop shorter. If you put a clean signal in, you'll get a clean signal out. Most of the trash you hear about these things is based on guys running a wide, over modulated, over powered signal through them to begin with.

[kk4fpx]

Well so far it seems to be doing the job.I got very good reports from Brazil and California so far.It's pretty broad banded 26 Mhz to 54 Mhz from what I can find out.I found the spec's on the tube model but not this one.It's designed for 4 watts in but I'm running 5 watts on my HTX-100,can't use the 10 because it 25 watts only.
I'd sure like to find the user's manual.I'm pretty sure I'm useing it right.I had to buy a 35 amp power supply for it,I only had a 12 amp one.I got a good deal on both at the Gadsden Ham Fest this morning.

[kb2vxa]

Don't tell anybody but I had something very similar a long time ago in a galaxy far away, nice clean signal and praise instead of bad reports. Just a simple, straightforward two transistor push-pull amp with a one transistor RX preamp and the usual RF sniffer relay control. Using an amp makes using a monitor scope all the more important, those CB amps are easily driven into Class C which seems to be the aim of those Chicken Band Outlaws that have given otherwise perfectly good amps a bad name. Palomar had a long trusted reputation for quality until it went out of business in 1980 unlike Dave Made or Texas Star junk.

[WØTKX]

True dat. Don't over drive the driver. They work OK. I poked around on the net, info is available for a price.

[NQ6U]

Palomar is a local company, based in Escondido. They don't build amps any more but they're still in business selling ferrite toroids and a nice (if pricey) kit for dealing with RFI issues.

[KA9MOT]

I might be off in my opinion. It may be OK on 10M. I wouldn't bet my ticket on it.

[N8YX]

Believe it or not, you may already be using a PA of that nature in your older U.S.-built amateur/commercial HF radio!

The circuit in question was used by Swan/Cubic and Ten-Tec - a modified version was used by Heathkit. I'm talking about the venerable 100/140w output (class AB/C) 2x MRF455/458 design which essentially was copied straight from Motorola's Application Notes.

There are provisos and caveats involved:

1) No low-pass filtering on the output assumes a very pure (band/low-pass filtered) input;

2) You must pay attention to biasing (particularly, in the area of thermal compensation) and drive levels.

3) Many CB amps of the day which used the design used RF output transformers that were simply not large enough for the task at hand and can easily be driven into core saturation.

Best way to use this amp is to construct a low-pass filter for both input and output, keep the drive down (use an input padder if necessary) and verify that the correct biasing scheme is in use. Most non-amateur market amps of the type don't have it, but if one studies the appropriate Application Notes one finds it's not that big of a deal to modify the existing design. Another thing I would recommend doing is looking into adding negative feedback by means of degenerative emitter swamping resistors - it'll prevent the transistors from going into oscillation at VHF in certain drive regimes.

All this info is readily available - either online, in a Radio Amateur's Handbook from the late 70s or from an older Motorola RF Power Devices book.

[PA5COR]

Most of these amps lack a bandpass filter as is obvious since it works over a very wide range without having to set the band switch, leaving all spurious a path to the antenna.

Also their bias circuit mostly leaves a lot to desire, i rebuild many of these amps, still have a KL 500 amp here as new that needs input and output bandpass filters and reworking the bias for the 4 MRF 455 transistors.

RF sniffer rx/tx switching bypassed to hard wire switching needs to be done as well.
I did a few of these and they can make 300-400 watts clean after reworking, not the 500-600 RM Italy claimed watts....
Good for prepping up 10-20 watt transceivers for a bit more output.
But then i have the Heathkit SB-1000 with new 3-500 ZG in it so i don't need them, i mostly sell them off when finished to hams here.
Add a few temperature controled fans on top as well.

They are basically the Motorola EB 104 design, from the Motorola transistor handbook i have sincee 30 years or so.

[kk4fpx]

Thanks for all the info,some of it over my head,I'm pretty much a plug and play kind of guy.I'm only a tech so 200 watts are all I'm allowed on 10 meters so I thought this amp would keep me legal.

[ki4itv]

GrrrDupe.

[ki4itv]

If you're only doubling your power by using that amp, you could get more out of a forward gain improvement using a better antenna...and not be so worried about the power output limitations of your license. (?)
You'd be hearing what you could work too.

[KA9MOT]

There are provisos and caveats involved:

1) No low-pass filtering on the output assumes a very pure (band/low-pass filtered) input;

2) You must pay attention to biasing (particularly, in the area of thermal compensation) and drive levels.

3) Many CB amps of the day which used the design used RF output transformers that were simply not large enough for the task at hand and can easily be driven into core saturation.

Best way to use this amp is to construct a low-pass filter for both input and output, keep the drive down (use an input padder if necessary) and verify that the correct biasing scheme is in use. Most non-amateur market amps of the type don't have it, but if one studies the appropriate Application Notes one finds it's not that big of a deal to modify the existing design. Another thing I would recommend doing is looking into adding negative feedback by means of degenerative emitter swamping resistors - it'll prevent the transistors from going into oscillation at VHF in certain drive regimes.

All this info is readily available - either online, in a Radio Amateur's Handbook from the late 70s or from an older Motorola RF Power Devices book.



Most of these amps lack a bandpass filter as is obvious since it works over a very wide range without having to set the band switch, leaving all spurious a path to the antenna.

Also their bias circuit mostly leaves a lot to desire, i rebuild many of these amps, still have a KL 500 amp here as new that needs input and output bandpass filters and reworking the bias for the 4 MRF 455 transistors.

RF sniffer rx/tx switching bypassed to hard wire switching needs to be done as well.
I did a few of these and they can make 300-400 watts clean after reworking, not the 500-600 RM Italy claimed watts....
Good for prepping up 10-20 watt transceivers for a bit more output.
But then i have the Heathkit SB-1000 with new 3-500 ZG in it so i don't need them, i mostly sell them off when finished to hams here.
Add a few temperature controled fans on top as well.

They are basically the Motorola EB 104 design, from the Motorola transistor handbook i have sincee 30 years or so.

And this is what I have been taught. Unfortunately, I don't know enough about amps to make these types of suggestions or modifications. What I do know is that most of these amps put out a signal on their harmonics and regardless on what the receiving station reports (most will say you sound good regardless), you are probably still transmitting on unintended frequencies, or a dirty signal.

If this is "over your head" as it is for me, it is best to err on the side of caution. For me, the belief that CB Amps are to be avoided will help keep me from being a Lid.... I make enough mistakes with-out bringing CB equipment into my shack.

[KA9MOT]

If you're only doubling your power by using that amp, you could get more out of a forward gain improvement using a better antenna...and not be so worried about the power output limitations of your license. (?)
You'd be hearing what you could work too.

This too! Is one S-Unit worth risking unwanted attention form your neighbors, fellow hams and the FCC?

[kk4fpx]

I did up grade my antenna.I went from a diy inverted v dipole to a three element Maco beam this did start giving me higher signal reports.But I had to give my call sign over and over before they got it,and only if the conditions were really good I could not have a good qso,just hi and bye.
So far with the amp I've actually been able to have longer qso's
I know this isn't the best of systems but I'm on a limited budget and this is the best I can do for now.

[WØTKX]

Clean RF brand sniffers, a scope, and that lovely Bencher low pass filter here. Along with an MFJ flavor of the cantenna. I can fire up anything and check it out before putting it on the air. And keep an eye on it while on the air.

Take pride in your signal, instead of your swinging.

I have often found transistorized outputs/amps to be fussier with signal artifacts than the tube stuff. Just remember, the difference of 10-20 watts when you are running 100+ is not significant and very often the extra punch ruins the intelligibility of your signal.

:werd:

[PA5COR]

Since i have the Yaesu FT 2000 D with 225 clean watts output, i mostly switch over to class A for using the amp, adding 10 dB extra lowering the spurious, and a clean signal to boort.
The 75 watts class A max is more then enough to drive the SB-1000 to full output, mostly i run just 400-500 watt anyway.
Since i got the 2000 D i hardly use the amplifier, the 200+ watts directly from the yaesu will do quite fine.

I made some rather good antenna's they work both ways, receive and transmit, i don't want to be seen as a crocodile, big mouth, small ears...
Use as much power you need to make a reliable qso, if that is 10 or 1000 watts.

[KA9MOT]

I did up grade my antenna.I went from a diy inverted v dipole to a three element Maco beam this did start giving me higher signal reports.But I had to give my call sign over and over before they got it,and only if the conditions were really good I could not have a good qso,just hi and bye.
So far with the amp I've actually been able to have longer qso's
I know this isn't the best of systems but I'm on a limited budget and this is the best I can do for now.

Really? I just saw a Heathkit HW-101 on QTH with power supply for $100. How poor are you? Is you ticket worth that single S-Unit? Is your reputation worth that S-Unit? Last year at this time I was begging for a loaner radio so I could get back on HF. I would never dream of using CB gear on Amateur Frequencies.

By the time you buy all the equipment/parts you need to clean that amp up, you'll have spent enough to buy a good used 100W HF rig. Hell, you've already spent that much on the garbage you have.

BTW, if you were going to ignore our advice, why did you ask our advice?

[WØTKX]

Because we are messed up?

[K7SGJ]

Because we are messed up?


Yeah, but we look good doing it.

[kk4fpx]

I just asked if anyone knew anything about this amp.Sorry.

[N8YX]

I just asked if anyone knew anything about this amp.Sorry.

Nothing to be sorry about. Study it, improve on the design and use the thing. None of us were born knowing this stuff; the hobby is all about learning. And sometimes, class co$t$.

[PA5COR]

Never be sorry for asking questions, i'd raather have people asking questions all day as making mistakes, they mostly are costly...
At least you do your experiments and try to get more knowledge all the hobby is about. ;)

[kk4fpx]

Also, I didn't say I wasen't going to take some of the advice I got like the low-pass input filter.and maybe the coil tap.Thanks for the good advice to those who offered it. :-)

[KC2UGV]

I just asked if anyone knew anything about this amp.Sorry.

Don't be sorry. Use what you have, and make it work. Just make it work properly.

I would most certainly put the low-pass filter on the output. They're somewhat inexpensive, so it's cheap insurance. And, start shopping for a station monitor, so you can keep an eye on your output.

That being said, the bump you get from this amp isn't very much. 90% of your station is antenna, and I had an HTX-10 for a looong time, and it worked well, without an amp, in a low spot for sun spots. 25W is more than ample for 10. That band is interesting, and it's almost an on/off thing, and more output power generally doesn't help much at all.

[KA9MOT]

Also, I didn't say I wasen't going to take some of the advice I got like the low-pass input filter.and maybe the coil tap.Thanks for the good advice to those who offered it. :-)

No, you didn't. Instead you said you were making contacts with it.

I apologize to you for coming across as an ass.

Once upon a time (when I was able), I was a pretty fair mechanic, especially when it came to Fords. People used to come to me, ask my opinion about their car, or some recent mechanic work and then ignore my advice. One example would be my wife's friend. She sent her car to a local mechanic (Whom she used for years) because it was over heating and using coolant (This screams head gasket). After she dropped the car off she asked me what I thought. I told her to hope for the best but to be prepared for a bad head gasket. 2 weeks later her mechanic told her the block was cracked which is possible (who am I to say, I didn't look at the car). 1 month later he called her and told her that when they pulled the engine out of the car, the engine broke into 2 pieces. I told her that was BS, she needed to go get her car. After a total of 3 months she finally got her car back with a $3,000 engine. How does a 4 cylinder for a 1989 Ford cost $3000? I told her to look and compare the VIN on the engine with the one on the dash. She didn't know where to look, so I did. Same VIN, and lots of new gaskets in the top end. The oil pan gasket was old.
I pointed that out, told her she'd been robbed and 2 days later when the tie rod he'd left loose finally popped off, she had the car towed back to him. I won't help her at all after that.

It really bothers me when somebody asks for an opinion, I take the time to give my best answer and it gets ignored.

[K7SGJ]

No, you didn't. Instead you said you were making contacts with it.

I apologize to you for coming across as an ass.

Once upon a time (when I was able), I was a pretty fair mechanic, especially when it came to Fords. People used to come to me, ask my opinion about their car, or some recent mechanic work and then ignore my advice. One example would be my wife's friend. She sent her car to a local mechanic (Whom she used for years) because it was over heating and using coolant (This screams head gasket). After she dropped the car off she asked me what I thought. I told her to hope for the best but to be prepared for a bad head gasket. 2 weeks later her mechanic told her the block was cracked which is possible (who am I to say, I didn't look at the car). 1 month later he called her and told her that when they pulled the engine out of the car, the engine broke into 2 pieces. I told her that was BS, she needed to go get her car. After a total of 3 months she finally got her car back with a $3,000 engine. How does a 4 cylinder for a 1989 Ford cost $3000? I told her to look and compare the VIN on the engine with the one on the dash. She didn't know where to look, so I did. Same VIN, and lots of new gaskets in the top end. The oil pan gasket was old.
I pointed that out, told her she'd been robbed and 2 days later when the tie rod he'd left loose finally popped off, she had the car towed back to him. I won't help her at all after that.

It really bothers me when somebody asks for an opinion, I take the time to give my best answer and it gets ignored.

Happens all the time. I think one notices it more as they age, at least I do. I don't let it bother me any more. Hell, I rarely take my own advice since I don't trust the source any more.

[WØTKX]

The best advice given here was how to use that simple amp in a clean fashion. It sounds like it is being used that way. A DX station might not be able to hear problems, but somebody with knowledge that is close buy would. Unfortunately, many people use their radios and amplifiers without regard to quality, just (poorly measured) power. And bad information is given.

This happens on 11 Mhz, but also on 75 meters, 20 meters, etc. Ever hear somebody over driving on PSK? :snicker:

This has the unintended consequences of giving a piece of otherwise decent equipment a bad reputation. Funny, that "undesirable" reputation happens to decent radio folks who started and/or still play on 11 Mhz. Even the good ones. And there are sensitivities to that, eh?

Hams use brick style solid state amps in VHF/UHF a lot, and they tend to suffer similar issues...
Don't drive 'em hard, don't assume your signal is good because it's loud.

[KA9MOT]

http://swap.qth.com/view_ad.php?counter=1017271

HW 101 in working condition. $175

[kb2vxa]

Uh, 11MHz isn't a ham band. (;->) Another uh, a station monitor is a super expensive piece of shop equipment, I think you meant a monitor scope. On that note, I've used shop scopes from Eico to Hewlett-Packard as monitor scopes with a hank of wire for a pickup antenna. If you go that route just put a 1mH RF choke across the input to swamp 60Hz line hum pickup.

[n2ize]

in my earliest days as a ham (1988 or 89 when I was still a tech for a short time) the ten meter band was wide open and I ran a borrowed Cobra CB rig that was converted to 10 meters. I also ran it into a sweep tube amplifier (probably built for CB) and into a vertical. It sounded great on 10 meter SSB. Got great reports from all over... Most of the time however I didn't need the amp.