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View Full Version : Technical reasoning for AM vs any other mode?



KC2UGV
05-04-2010, 09:15 AM
Other than the "sounding better" reason for using AM, are there any technical advantages to using it over, say SSB or digital voice?

PA5COR
05-04-2010, 09:21 AM
Antique modulation..:shifty::-P
Though it can sound perfect with the right gear
SSB is what i use and with correct settings of alc, good microphone, some equalizer settings ( EQplus here) it also can sound very good.
For AM i use the FT 100 with AM 6 Kc Xfilter, 25 watt carrier and modulated to 100 watts it sounds very nice ( according to others) with the standard handmike.

Just whatever rocks your boat :-D

WØTKX
05-04-2010, 09:41 AM
I like AM, because done right, it sounds really good. However, SSB with my Kenwood TS-850 and DSP-100 set to wide transmit... "ESSB".

It sounds just as good, and is more efficient. I can pinch it down to 2.2 K wide with the DSP-100.

My Ten Tec Pegasus is even more versatile, but it's not quite as listenable as the TS-850 is on receive.

N8YX
05-04-2010, 11:10 AM
Other than the "sounding better" reason for using AM, are there any technical advantages to using it over, say SSB or digital voice?
SSB requires more complex equipment to demodulate and present the received signal - BFO, filtering and all that.

An AM transmission can be copied by a simple receiver - which may consist of just a tunable tank circuit, diode detector and headphones.

The advantage lies at the receiving - not the transmitting - end of the link.

KC2UGV
05-04-2010, 12:49 PM
SSB requires more complex equipment to demodulate and present the received signal - BFO, filtering and all that.

An AM transmission can be copied by a simple receiver - which may consist of just a tunable tank circuit, diode detector and headphones.

The advantage lies at the receiving - not the transmitting - end of the link.

That's pretty much the only one I could come up with, receivers are so easy to build. A coil, a sliver of graphite, a razor blade, and a crystal set headphone, and you got a AM receiver.

N8YX
05-04-2010, 01:04 PM
That's pretty much the only one I could come up with, receivers are so easy to build. A coil, a sliver of graphite, a razor blade, and a crystal set headphone, and you got a AM receiver.
In addition, both ends of an SSB link must be fairly stable in regards to drift. An AM link is more tolerant of a few hundred hertz of drift on either end. As long as the transmitted signal doesn't slip too far out of the receiver's passband, decent copy can still be maintained.

N4VGB
05-04-2010, 01:09 PM
In double blind testing of the ability of those in a test group to correctly copy a voice signal during conditions of fade, noise, etc., AM always wins over FM & SSB.

N9FE
05-04-2010, 01:59 PM
It's just another mode. AM is fun. So is ssb Cw psk fm . Whatever your into. USE !! the bands !

kb2vxa
05-04-2010, 02:13 PM
AM is more fun, especially when it's done with fire bottles, heavy metal and my favorite...

W4GPL
05-04-2010, 03:12 PM
9 posts in and no bandwidth Nazis? :chin:

ki4itv
05-04-2010, 03:26 PM
Hell, as long as you're not moving non-ham traffic to and from the internet ...who gives a flip?
:-P :-D
hehe.

(I kinda miss that anti-Winlink Warlord descriptor under my call) :yes:

PA5COR
05-04-2010, 03:47 PM
AM is perfectly legal here as it is in your region.
I wanted to keep AM so i bought and inserted the AM Xfilter in the FT 100 which is used for that purpose on the 3702 AM net here, people use all kind of old ( ww2) gear, old ship transmitters etc, so i just chug along there.

The 2 FT 847's will do low level AM, which is nothing compared to the 6 Kc AM signal from the FT100.
They do a fine job with the Collins filters on SSB though
The 2 FT 847's have now an added referrence Xtal oven, which keeps them very stable.

I started to work 2 meters in AM, then FM, and soon after that made my first SSB IF in 9 MHz.
Yes, i still listen on AM 540 - 1650 KC band too :D

N9FE
05-04-2010, 03:56 PM
9 posts in and no bandwidth Nazis? :chin:
The AM bunch are really only in very small areas. Even on the 75 meter "getto" portion, They don't bother anyone. Theres a group on 1.995 at night as well. Just like CW, If you want to operate that mode, Go there. There really is room for everybody. Just that some won't or cannot move, You know.. "rock bound" In there heads only.

WØTKX
05-04-2010, 04:01 PM
I like those big AM round tables. Some of those ops are glorious windbags, and a few are pretty damn funny.

Will join 'em when I can run more than 30-40 watts.

N9FE
05-04-2010, 04:07 PM
When i had the 500m or the 811< i only fed it with like 15 or 20 watts. That gave 200 250 out. Which is plenty. But you really got to watch your heat factor. Kinda limit your gab time. The big AM boys got the stuff and the fans for the looong key downs. Most flip a switch on the old stuff.. No ptt

N4VGB
05-04-2010, 05:38 PM
When i had the 500m or the 811< i only fed it with like 15 or 20 watts. That gave 200 250 out. Which is plenty. But you really got to watch your heat factor. Kinda limit your gab time. The big AM boys got the stuff and the fans for the looong key downs. Most flip a switch on the old stuff.. No ptt

Fans are disdained by many AM ops, noise in the broadcast studio!:lol:

Even some of the older AM broadcast xmitters of 250-500 watts were convection cooled only, no fans, no background noise.

A lot of the AMers using AM broadcast xmitters and even militray gems like the T-368 put the xmitter outside the shack area and operate them remotely.

Dats one of the reasons AMers still cling to the old big glass tubes like 810s, 833s, 304s and even 450s. Up to a certain power level, convection cooling is all that's needed.

KA5PIU
05-04-2010, 09:23 PM
Hello.

AM is easy on Transmit as well as Receive.
The easiest AM transmitter would be dual triode from an old TV set and a telephone carbon microphone.
The tube came from an old Sears Silvertone portable TV that had all the filaments wired in series, AC-DC style.
A few other parts from said defunct TV and perhaps other junque and I was all set.
In East Germany a few people had car radios with simple AM transmitters added and would operate just above the broadcast band.
Tuning was done with the vericap of the radio by way of the LO + a 456 KHz offset.

kb2vxa
05-05-2010, 05:09 PM
It has come to the point where I feel compelled to post this famous one again as it probably got lost in changes.

WØTKX
05-05-2010, 07:27 PM
Please click to enlarge. :snicker:
2698

N4VGB
05-05-2010, 09:48 PM
It has come to the point where I feel compelled to post this famous one again as it probably got lost in changes.

WA1HLR/Timtron, still corrupting the youth of America.

http://www.youtube.com/watch?v=Sl-DY8IsUB0

Oh yeah, it's those PW mobile blues.

N4VGB
05-06-2010, 06:32 AM
Yo Corey, I almost forgot one very important reason why AM is still popular.

Because you can't build either a filter or phasing type SSB transmitter in the fashion shown in the pic and get the thing to work!:lol:

Yes, it is an actual working AM transmitter and it works very well indeed.:yes:

2705

KC2UGV
05-06-2010, 07:21 AM
Yo Corey, I almost forgot one very important reason why AM is still popular.

Because you can't build either a filter or phasing type SSB transmitter in the fashion shown in the pic and get the thing to work!:lol:

Yes, it is an actual working AM transmitter and it works very well indeed.:yes:

2705

Interesting pic. Wouldn't want to be in that room while the thing is keying, but interesting to say the least :) But, I know why it's popular, lot's of people want to use it. I just was trying to figure out what the technical "pros" of AM vs X was.

N4VGB
05-06-2010, 07:36 AM
Interesting pic. Wouldn't want to be in that room while the thing is keying, but interesting to say the least :) But, I know why it's popular, lot's of people want to use it. I just was trying to figure out what the technical "pros" of AM vs X was.

You're using AM every time you make a SSB contact, SSB is Amplitude Modulation.

N9FE
05-06-2010, 08:12 AM
I hope o'l Clyde never runs that mess in the dark.. Could be shocking

N4VGB
05-06-2010, 08:30 AM
I hope o'l Clyde never runs that mess in the dark.. Could be shocking

I've got a friend who visited Clyde once and swears that he had one foot on top of the HV xformer and the other on top of the mod xformer!:pray:

Clyde has been operating that rig for years in that configuration, I offered a free rack cabinet for him to put that thing in several years ago, the reply returned from the 3rd party who delivered the message was no. As Clyde once explained, it was a temp experiment that worked so well he decided to leave it that way.

He also has an AM BC xmitter, don't know if he ever got it retuned for ham use or not???

N9FE
05-06-2010, 08:57 AM
Theres a guy up here that never puts the covers back on anything. I mean anything. Still waiting for the call from his son saying... Dad had a fire last night.

KC2UGV
05-06-2010, 12:10 PM
You're using AM every time you make a SSB contact, SSB is Amplitude Modulation.

Sorta a half-truth, wouldn't you say? Sure, it uses amplitude modulation, but it [SSB] uses half the bandwidth, and has the carrier suppressed.

WØTKX
05-06-2010, 01:18 PM
http://n4kc.blogspot.com/2009/04/am-vs-ssb-retro-battle-or-much-ado.html


It reminds me so much of the SSB vs. AM wars way back in the late-50s/early-60s, except this squabble is 180 degrees out of phase with that one. I was there for the end of that, when guys who clung to AM cussed the "Slop Bucket Boys" and tuned up on top of them for hours to demonstrate their disdain. It got ugly, but for the very reason cited above--who gets the worst of the QRM--it eventually was won by SSB (Yes, there were other reasons...SSB is simply a better mode, more efficient).


Also...

John, NU9N has great info on his site, and is great to have a QSO with.

http://www.nu9n.com/apologetics.html

N8YX
05-06-2010, 05:28 PM
Go ahead and heterodyne all ya want, boys - this little contraption with its auto-notch feature is the sure cure for 'carrier-throwers'.

http://www.timewave.com/images/DSP-599zxHeadONcrop1.jpg.

N4VGB
05-06-2010, 07:08 PM
Go ahead and heterodyne all ya want, boys - this little contraption with its auto-notch feature is the sure cure for 'carrier-throwers'.



Why fight a carrier? Zero beat it and let your SSB signal take a free ride!

n2ize
05-09-2010, 06:06 PM
There is no major technical advantage to using AM. It's just a thing some of us like to do. For some, it's the high fidelity. For others it's the simplicity and "vintage-ness" of it. For others it's the restoration and operation of old vintage equipment that has only AM / CW capability. For many it's a combination of all the above. There is a certain sense of warmth and accomplishment when you have a heavy piece of iron with glowing tubes and the smell of dust burning off hot components on a cold day. Or the sense of accomplishment in home brewing a transmitter or bringing an old piece of gear back to life.

WØTKX
05-09-2010, 06:09 PM
Another Eico 720 w/730 modulator missed. Dang. Someday, I'll snag dat.

N4VGB
05-10-2010, 08:26 AM
Another Eico 720 w/730 modulator missed. Dang. Someday, I'll snag dat.

Not if the audiophools keep sucking up all the Eico 730s.:yuck:

W3WN
05-11-2010, 11:59 AM
Other than the "sounding better" reason for using AM, are there any technical advantages to using it over, say SSB or digital voice?
It's easier for you as an individual to design and maintain an AM transmitter. That's about it.

AM uses a 6 kHz or greater bandwith, SSB uses 3 kHz.
True A3 -- Amplitude Modulation, Double Sideband, Full Carrier -- splits output power 3 ways... 1/3 to each sideband, 1/3 to the carrier. Since true A3J (J3E) -- Amplitude Modulation, Single Sideband, Suppressed Carrier -- only transmits 1 sideband, it gets all the power. So an AM signal effectively has 1/3 the "punch" of an SSB signal.

That being said, nothing sounds as good on the air as a true, pure, AM signal in a properly maintained transmitter (ie, don't overmodulate!). The only thing that comes close, and it does come very close, is a Phasing SSB signal, as opposed to a Filtered SSB Signal. If you ever hear a Hallicrafters HT-37 transmitter on the air, you'll know what I mean.

KG4CGC
05-11-2010, 02:14 PM
A set up to make Clyde jealous.

http://i25.photobucket.com/albums/c79/bebop5/cccp_076_127.jpg

N4VGB
05-11-2010, 06:09 PM
It's easier for you as an individual to design and maintain an AM transmitter. That's about it.

AM uses a 6 kHz or greater bandwith, SSB uses 3 kHz.
True A3 -- Amplitude Modulation, Double Sideband, Full Carrier -- splits output power 3 ways... 1/3 to each sideband, 1/3 to the carrier. Since true A3J (J3E) -- Amplitude Modulation, Single Sideband, Suppressed Carrier -- only transmits 1 sideband, it gets all the power. So an AM signal effectively has 1/3 the "punch" of an SSB signal.

That being said, nothing sounds as good on the air as a true, pure, AM signal in a properly maintained transmitter (ie, don't overmodulate!). The only thing that comes close, and it does come very close, is a Phasing SSB signal, as opposed to a Filtered SSB Signal. If you ever hear a Hallicrafters HT-37 transmitter on the air, you'll know what I mean.




The word "easier" is difficult to grasp in this topic. It's cheaper, takes less parts and labor to build a SSB rig than a plate modulated AM rig.
What an opening for a tech debate! Close but no ceegar OM.
An AM or SSB signal can be much wider or narrower than 3-6kc, the SSB signal can easily exceed 6kc and the AM signal can be narrower than 6kc.
Signal "punch"? I just gotta find me a "punch" meter!? I only have RF voltage and amperage and wattage measuring capability.
Close but no ceegar on AM power OM. The book says 1500 watts PEP for all types of emissions and at least 1-2 out of 10 hams actually give a hoot. Anyway, a 100% symmetrical modulated AM signal is comprised of 375 watts of carrier power and 562.5 watts in each sideband. The difference in received signal strength between a 562.5 watt SSB signal and a 1500 watt SSB signal isn't squat, your ears won't know the difference.
Not to even mention that having duplicate voice information contained in both sidebands can defeat interference and noises coming from only one side of the signal center and the carrier has a quieting effect on a receiver that is missing in SSB reception. During normal SSB voice reception your ears are subjected to more of the ambient noise level than the desired received signal, since human voice and SSB are low duty cycle affairs.
The HT-37 I'll agree with, since that is the reason I own one.

n2ize
05-12-2010, 03:25 PM
You've got to put a good compressor/peak limiter in line. You want to get some asymmetry in that waveform. I started with a simple diode clipper and then I ran a BL-40 compressor/peak-limiter to give me a little bit of asymmetrical peak limiting that + a little equalization in the low level audio chain. The result. Good fidelity, plenty of PUNCH uet without producing distortion, buckshot and splatter. I could turn the gain way up on the microphone input and you could hear every little sound in the room, i.e. the sound of bubbles in my aquarium, the whisper of the winds at the window yet I could come right up to the mic and close talk at a normal volume without producing distorted overmodulated audio. Of course in general I never kept the input gain up that high, but it was nice to do now and then to demonstrate the capabilities of a good audio chain.

Seems like the way a lot of AM'ers these days are going is the class E route. As the price and availability of tubes and heavy iron goes scarce and prices go through the roof it's interesting what can be done with a bunch of power MOSFET's and some time and patience. Fully solid state, transformerless, modern, clean, efficient, and state of the art. Really interesting stuff.

KG4CGC
05-12-2010, 06:31 PM
A good guitar amp in the front for the audio really helps. Usually an amp with a strong pre-amp, 6L6's come to mind, is a good start for an audio driver. The trick is keeping the tubes hot. Hot makes them mellow and full of those juicy harmonics that tube heads crave.

WØTKX
05-12-2010, 06:40 PM
http://www.w3am.com/8poleapf.html

N4VGB
05-12-2010, 08:27 PM
Audio processing for amateur radio AM operation is not necessary at all. Half of the crap on the web concerning the subject is pure poppycock. Not to mention the FACT that many pieces of amateur AM gear were never designed with enough PS "headroom" to allow a very large increase in the average audio/power output level without sucking more than the PS was able to provide. Which results in some nasty things happening to an AM signal.:irked:

Clean, natural and undistorted audio should be the goal.

KG4CGC
05-12-2010, 08:34 PM
Audio processing for amateur radio AM operation is not necessary at all. Half of the crap on the web concerning the subject is pure poppycock. Not to mention the FACT that many pieces of amateur AM gear were never designed with enough PS "headroom" to allow a very large increase in the average audio/power output level without sucking more than the PS was able to provide. Which results in some nasty things happening to an AM signal.:irked:

Clean, natural and undistorted audio should be the goal.
I don't think you know what you're talking about.

KC2UGV
05-12-2010, 08:38 PM
I don't think you know what you're talking about.

You mean Big Green Radios + Military Whips only guy doesn't know what he's talking about? Or, Mr. SSB is AM Guy?

N4VGB
05-12-2010, 08:44 PM
You mean Big Green Radios + Military Whips only guy doesn't know what he's talking about? Or, Mr. SSB is AM Guy?

SSB=half a proper amateur voice signal.:lol:

KC2UGV
05-12-2010, 08:54 PM
SSB=half a proper amateur voice signal.:lol:

SSB = Less bandwidth hogging :) But, still getting your contact.

N4VGB
05-12-2010, 09:21 PM
SSB = Less bandwidth hogging :) But, still getting your contact.

Don't worry Corey, your new radio may be obsolete and unusable sooner than you think. Digital, digital, digital, the FCC is all gaga over digital transmission. TV, FM, AM already done.

http://en.wikipedia.org/wiki/D-STAR

When Japan speaks the ARRL and FCC sit up like trained dogs.:sadwave:

KC2UGV
05-13-2010, 06:23 AM
Don't worry Corey, your new radio may be obsolete and unusable sooner than you think. Digital, digital, digital, the FCC is all gaga over digital transmission. TV, FM, AM already done.

http://en.wikipedia.org/wiki/D-STAR

When Japan speaks the ARRL and FCC sit up like trained dogs.:sadwave:

PSK will, for the foreseeable future, always use USB :p Thanks for the concern though.

ki4itv
05-13-2010, 06:35 AM
Don't worry Corey, your new radio may be obsolete and unusable sooner than you think. Digital, digital, digital, the FCC is all gaga over digital transmission. TV, FM, AM already done.

http://en.wikipedia.org/wiki/D-STAR

When Japan speaks the ARRL and FCC sit up like trained dogs.:sadwave:
If they want to put amateur radio into its final death throws, that would probably do it for me.
You'd find me burning clay, blowing glass, and beating the shit out of metal.
Old technology is cool and close to the heart. New technology is purely utility, its usefulness being its only true asset.

N4VGB
05-13-2010, 11:22 AM
If they want to put amateur radio into its final death throws, that would probably do it for me.
You'd find me burning clay, blowing glass, and beating the shit out of metal.
Old technology is cool and close to the heart. New technology is purely utility, its usefulness being its only true asset.

My feelings precisely!:agree:

W1GUH
05-17-2010, 12:03 PM
There's nothing like a really good belch over a high power, hifi AM signal, especially with good received audio! They just don't sound proper on SSB.

And keep looking for that 720/730 setup. I saw one at a hamfest about a month ago...they're still there, but will take a little patience. The '730 is a hella good mod box after ripping out the clipper and filter. Well, no, there's no "ripping out", unless you call pulling a tube "ripping out!". It's very easy to make that baby sound really, really good!

KC2UGV
05-17-2010, 12:08 PM
So, more or less, the common idea is a AM station (Properly set up):

* Easier to build and maintain
* Better fidelity

Wouldn't both of those features be extremely valuable, since Better Fidelity would mean less chance of a non-receipt of a message (Can lose more "information" before it's unintelligible) and well, easier to build from "scrap" parts?

WØTKX
05-17-2010, 12:54 PM
I'd say the best compromise is eSSB setup for your voice and station characteristics. I've had great fun ragchewing with folks running 4-6 k wide, and it makes a difference. However, some gotta turn those knobs to "11", and a good setup can sound really crappy.

High Fidelity AM (http://www.nu9n.com/am.html)

High Fidelity eSSB (http://www.nu9n.com/essb.html)

PDF file about speech bandwidth, articulation, etc (http://www.nu9n.com/images/Sound.pdf)


While most of the average energy in English speech is
in the vowels, which lie below 3 kHz, the most critical elements
of speech, the consonants, lie above. The difference between "f"
and "s," for example, is found entirely in the frequencies above
3 kHz; indeed, above the 3.3 kHz telephone bandwidth entirely.
Note (Figure 1) how the burst of high-frequency sound that
distinguishes the "s" in "sailing" from the "f" in "failing"
occurs between 4 kHz and 14 kHz. When these frequencies are
removed, no cue remains as to what has been said.

w6tmi
05-21-2010, 01:06 AM
Antique modulation..:shifty::-P
Though it can sound perfect with the right gear
SSB is what i use and with correct settings of alc, good microphone, some equalizer settings ( EQplus here) it also can sound very good.
For AM i use the FT 100 with AM 6 Kc Xfilter, 25 watt carrier and modulated to 100 watts it sounds very nice ( according to others) with the standard handmike.

Just whatever rocks your boat :-D


'zactly. If ya feel like running Ancient Mary, why not? It's a hobby, doesnt always have to be "the best method".

N4VGB
05-21-2010, 01:49 PM
I hope nobody starts to apply the "Technical reasoning for" idea to many things in this world! Amateur radio itself doesn't hold up so well under that scrutiny.

Old cars, old airplanes and old motocycles gone!:angry:

KC2UGV
05-21-2010, 01:58 PM
I hope nobody starts to apply the "Technical reasoning for" idea to many things in this world! Amateur radio itself doesn't hold up so well under that scrutiny.

Old cars, old airplanes and old motocycles gone!:angry:

I think you missed the point of my question. I was merely asking to get a bit more knowledge on the pro's and cons of various emission types. More or less so (In my mind) so everything doesn't start looking like a nail to me :)

N4VGB
05-21-2010, 02:00 PM
I think you missed the point of my question. I was merely asking to get a bit more knowledge on the pro's and cons of various emission types. More or less so (In my mind) so everything doesn't start looking like a nail to me :)

There aren't many pros and cons to emission types. It's all good except for those damnable "we rule the airways" Winlink lids.

KC2UGV
05-21-2010, 02:04 PM
There aren't many pros and cons to emission types. It's all good except for those damnable "we rule the airways" Winlink lids.

Ok, maybe a better wording: What would work best when... Example, using AM to put out a PSK signal would be a waste of spectrum.

kb2vxa
05-21-2010, 06:40 PM
"There's nothing like a really good belch over a high power, hifi AM signal, especially with good received audio!"
Another Henry Yell ARRRRRR fan revealed. (;->)

N4VGB
05-21-2010, 06:53 PM
Ok, maybe a better wording: What would work best when... Example, using AM to put out a PSK signal would be a waste of spectrum.

Then amateur radio should be CW only, since it's the narrowest emission type available.

KC2UGV
05-21-2010, 08:40 PM
Then amateur radio should be CW only, since it's the narrowest emission type available.

Kinda hard to do AX.25 over CW...

W1GUH
05-28-2010, 01:24 PM
"There's nothing like a really good belch over a high power, hifi AM signal, especially with good received audio!"
Another Henry Yell ARRRRRR fan revealed. (;->)

:agree::cheers:

Love them 50C5's!

Vinnie
06-09-2010, 02:00 PM
Ah, the good ol'days.
Back in So.Dak we had an elderly farmer, W0NNX, running a Johnson Desk Kilowatt on AM, loading his miles of electric fence. Used to stop and chat with him every week as I came and went to school. Now AM is just a hobby diversion for a few. Still, 'real hams' operate CW, and always will......