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Author Topic: WHERE HAS ALL THE AM GONE?  (Read 1227 times)
AC0FA
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Posts: 298




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« on: August 13, 2007, 09:37:16 AM »

Hello all,
I have a question that calls for some personal opinions. About AM activity.

I am new to the AM mode It would seem from listening and calling CQ with 70 Watts out day and night all last week and this weekend that there is not much AM activity in the Midwest. Minnesota Wisconsin, Iowa.

I have been tuning around on 40 and 80 meters. Where the AM has traditionally been. net frequencies posted on the internet. Posted midwest calling frequencies and heard no carrier signals.

Single Side Band still works and my antenna Hasn't fallen over.

Is AM a more of a local phenomenon on the east and west coast?

I can pick up ssb from coast to coast with no problem.  

The local brodcast stations sound great. If there are ham AM stations there I can't pull them out of the mud.

Of course the SSB stations sound terrible on my AM only receiver HQ-129X. I can pick up code no problem. I am just not finding any am carriers in the ham bands.

Any advice or info would be great.
John            
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AF9J
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Posts: 71




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« Reply #1 on: August 13, 2007, 01:04:26 PM »

Hi John,  

There are some of us on AM in the Midwest.  One of the problems at the present time, is the seasonal QRN, that drives a lot of the AMers off of their tradtional low band freqs.  But there is a reagular group of VE3s that meets on 3725.  There is also the Midwest Calssic Radio Swap Net that meets on 3885, at 7:30 AM on Saturday mornings.  Many AMers, who don't even have anything to sell, check in or have QSOs before or after the Swap Net. Also, some of us are having fun doing AM on 10 & 6m, when those bands open up.   For more info, may I suggest checking out the AM Forum (which I belong to):

http://amfone.net/Amforum/index.php

Some of us occasionally try to set up skeds via the AM Forum.

73,
Ellen - AF9J
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WB2WIK
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Posts: 20537




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« Reply #2 on: August 13, 2007, 01:59:18 PM »

If you have a good 20m antenna, also try 20 AM: It's almost all on 14.286 MHz, but a good group of guys, usually round tables and a lot of tech talk.

I get on 14.286 AM now and then, and it's fun -- the band's open with low noise levels when 40m, 75m and 160m are not.  Since 20 is a very crowded band, I don't try to use "hi fi" bandwidth, and roll off everything above 3 kHz using the DSP (transmit)filtering in the rig.  Still sounds good and doesn't create many complaints.

If you want "hi fi" AM, go to the AM frequencies on 75m, or up high in the 160m band, or wait until propagation returns to 10m and use the frequencies up around 29.0 MHz.

WB2WIK/6

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AC0FA
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Posts: 298




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« Reply #3 on: August 13, 2007, 04:52:30 PM »

Thanks for the info.

Having the time and frequency for expected activity really helps.

Some times its hard to tell from published information what frequencies are in use on a seasonal basis.

This info will increase my chances of completing a QSO.

John AC0FA  
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ONAIR
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Posts: 1732




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« Reply #4 on: August 13, 2007, 11:37:01 PM »

    Plenty of AM still on 11 meters! Smiley
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KE3WD
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Posts: 5694




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« Reply #5 on: August 15, 2007, 09:51:44 AM »

Let's talk about how to set up a modern rig to run AM for a minute.  

Because it may just be a case where your sound on the air, your signal, your modulation, are not going to get an AM enthusiast to answer you when you call the CQ thing.  

And also because when you first check in to an AM net or sked, you want to put your best foot forward the first time and avoid the on-air lecture from the old fart, right?

A lot of hams who have not the experience with how to set up their modulation chain when on the AM band have terrible AM signals and don't know why.  If you are not one of them, then just forgive me, plenty of others around to read this missive that can and should benefit by what I'm about to say.  

*Once upon a time, it was the ham community who spoke of "Forward Modulation" and "Backwards Modulation" on the AM mode, today there may be a lot of confusion about a perfectly good term because of the CB thang, don't fall prey to this.  

*What sounds best, and what we want to see at the other end is your dead key putting the S meter at one place and then when you talk, the meter needle swings Forward on your voice peaks.  Not backwards.  

*Backwards modulation is caused by running the RF output too high or the AF output too low or a combination of the two.  

*This is exacerbated if you are using a linear amp.  

*A peak reading wattmeter is really the thing to have, but you can also use an averaging wattmeter to see this happen as you modulate.  Just won't see as much swing on the meter.  If the meter stands still when you talk, or moves in the reverse direction, you need to turn that RF gain DOWN until it does.  

*Don't worry, you won't lose any power here, it will just be placed in the sidebands and not on the carrier, which in the AM mode is where it belongs.  

*Overdoing the forward swing is what can lead to overmodulation, too.  There is that magic 100% modulation happy point to find.  

Set it up properly and you can often fool that old timer on the other end into hearing an older high level modulated boat anchor AM rig using your modern solid state radio and amp.  

Recording your test transmissions on a monitor receiver and listening to the playback can help a lot here, adjust things, rinse and repeat until what you hear on the recording sounds splendid, all the while keeping an eye on that Forward Modulation aspect.  


KE3WD
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AC0FA
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Posts: 298




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« Reply #6 on: August 16, 2007, 09:34:31 AM »

KE3WD,
Thank you for the valuable information.
Excellent operating tips and procedures on AM modulation. Are few and far between on the internet.

I have noticed the 100w (450w PEP) Hollow State AM rigs flying off the shelves on ebay.

With the relaxation of the requirements for general class license. Combined with an gradual increase in AM popularity. It may be time for an AM article on
e-ham. Although, I would not be the one to write it.

I would read it twice and tape it to the desk.

I have had some success running 130w input into the Swan 700CX and injecting 15w carrier. 70W pep output.
of Ballance Modulator Generated AM sounds pretty good on the Hammarlund HQ-129x. When I get the dow key hooked up tonight I will be ready to roll.

In order to promote the Ham Radio art keep the Good Information coming.

John    

         
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AD5KL
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Posts: 18


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« Reply #7 on: August 16, 2007, 07:29:32 PM »

AM sounds really great - the problem for me would be trying to come up with something to say for 5 minutes of solid key down.  Some of those guys can give a longer monologue than Johnny Carson.

But the mode sure makes the listening a lot easier, instead of Donald Duck.
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ONAIR
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Posts: 1732




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« Reply #8 on: August 17, 2007, 05:38:45 PM »

    AM is trying to make a comeback.  We just need to try to generate more interest in the mode.  Check out the websites devoted to AM.
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AF9J
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Posts: 71




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« Reply #9 on: August 18, 2007, 08:51:16 AM »

Here are some websites with good info:

AM GENERAL INTEREST

AMfone:  http://amfone.net/Amforum/index.php

The AM Window: http://www.amwindow.org/

As some have mentioned, rig setup is pretty critical.  This is especially true of today's modern day rigs.  If set up properly, some of the newer rigs sound pretty good.  If not, they can sound pretty awful.  Steve, WB3HUS has a webpage on the AM Window site that has good info, on setting up a modern rig for AM.  Here it is:

 http://www.amwindow.org/tech/htm/plastic.htm

There is also a section of the AM Forum that has discussion threads dealing with use of some of the more popular modern rigs on AM:

http://amfone.net/Amforum/index.php?board=49.0

BTW, don't expect even a tube SSB rig to run full power on AM.  Typically, as a rule of thumb, AM carrier power is 1/4 the amount of a max power SSB or CW signal.  Even then, you may not run it at max carrier power for a couple of reasons: 1.) you get better audio on AM, with less drive in some rigs (most manuals say that for AM usage, the ALC should just barely kick during voice peaks); 2.) some finals last longer when you run less carrier power (this is especially true of Swans - I had a 270B that was like this).  Also, remember most vintage SSB rigs (Hallicrafters, Drake, Swan, Yaesus made through the early 80s, etc.) really ran AME (AM equivalent - SSB with a carrier).  Nevertheless, some of them sounded pretty good.  The only exception to this would be the early SSB tranmsitters that used phasing to generate the SSB (such as the Gonset G-100, Central Electronics CE10; CE20; CE100; & CE200, etc.).

73,
Ellen - AF9J
Contester, QRPer, VHF/UHF weak signaller & AMer
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KC4YOY
Member

Posts: 4




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« Reply #10 on: August 18, 2007, 12:55:00 PM »

We've got a fairly active group here in the Carolinas.
I just got a new (old) vintage AM station set up
this week. It's Viking 2 transmitter and a National 183D receiver, feeding a G5RV at about 50 feet.
You can see a photo of the AM station here,
http://radioheaven.homestead.com/AMstation.html

We're on 75 a lot around 3880 or 3885,
for almost 3 hours this morning.
The static crashes in the evening make it really
tough to hear unless they're a big gun.
W2DTC from NJ came blasting in last night hitting
40 over and sounding like WLW, what a signal.
Of course he couldn't begin to hear me over the
static.

We also are active on 6 meter AM a good bit
on 50.300. When the band opens it's great.

73, Ron kc4yoy
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AF9J
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Posts: 71




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« Reply #11 on: August 18, 2007, 09:29:36 PM »

6m AM's a blast!  Some of us on the AM Forum (Mark, K3MSB, and I), love to work 6m AM when the band is open.  10m AM is also fun.

73,
Ellen - AF9J
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G3VEL
Member

Posts: 2




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« Reply #12 on: August 20, 2007, 01:56:29 PM »

One thing I used to prefer about AM was the ease of tuning it in. It also has a more quality sound to it.

I have been toying with the following idea for a while now, which I think is possibly how Armstrong hit on the idea of FM:

Consider this question: For frequencies where most of the noise is atmospherics, does each channel have its own independent source of narrowband atmospheric noise, or is it the same collection of wideband atmospherics sources that affect all channels?

If the latter, which I believe to be true, then we have the same AM noise in each channel, although its phase may be different.

So, how about a receiver that received AM on two adjacent channels, and you subtracted the detector outputs? Would the noise cancel? I believe that it substantially does. Now, in order to communicate, you put out AM signals on both frequencies, but INVERSELY modulated, so that the detector outputs add at the subtactor.

Such a signal resembles FM, as the energy seems to be moving back and forwards between two frequencies, but the difference is - no higher order Bessel function sidebands.

I think the above thought process is probably what Armstrong went through in inventing FM.
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AC0FA
Member

Posts: 298




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« Reply #13 on: August 21, 2007, 10:50:27 AM »

Nah,
AM gives us an excuse to run 3 phase into a vintage commercial broadcast transmitter. With lots of gauges and really big tubes and stuff. And look alike a mad scientist. I think am transmitters were the main reason why hams need a license.
Pretty wild stuff.

400w carrier will smooth out the atmospheric noise real good. Ever tune to 3885 and hear dead quiet.
Just a big gun who forgot he was on vox.
John    
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ONAIR
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Posts: 1732




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« Reply #14 on: August 21, 2007, 12:56:57 PM »

     It was always quiet when "Powerman" would throw a dead carrier on CH 10 all night!
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