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Vietnam, Military AM Last Hurrah?




 
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Author Topic: Vietnam, Military AM Last Hurrah?  (Read 2701 times)
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KA3EKH
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« on: March 23, 2018, 03:19:55 PM »

My favorite pastime over the last several years has been reading about the Vietnam War. Keeping in mind that I was all of about fourteen when it ended but did grow up on a military base and was aware of everything that was going on at the time.
Many radios like the GRC-19 (T-195/R392), or the GRC-9 were field radios designed for AM operation. Larger tactical sets like the AN/GRC-26 with its T-368 and stacks of R-390 receiver although designed primarily for teletype did also support AM.
With FM radios like the PRC-25/77 or the VRC-12 family of radios intended for short range field use and all the long range voice supported by SSB radios like the PRC-47, PRC-70, PRC-74, AN/GRC-106 and last but not least the ubiquitous Collins KWM-2A cannot see where AM was used. Have read things like where unofficially crews took things like T-368 transmitters and removed the modulator deck, shortened the case and use it as a portable Teletype transmitter so apparently AM was not highly valued.
I know that AFVN operated AM broadcast operations throughout the country and there appears to have been hundreds of AM/CW only AN/GRR-5 receivers that were used for something so somewhere larger AM transmitters must have been used to broadcast to them?
 Large tactical networks were VHF multiplexed and VHF Troposcatter systems like the MRC-85 sets that carried lots of multiplexed telephone channels and early satellite systems like the MSC-44 that linked Vietnam back to Hawaii from outside of Saigon, the center of communications for all of Vietnam.
Saigon also operated HF channels to the Philippians, Okinawa and Bangkok but going to assume they were SSB.
The only place I can think of where AM stood tall was as still is today Aircraft communications being that was all VHF AM. So what I am asking here is if anyone knows of AM operations during the war? Or do we have to go back earlier to Korea?



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w1vtp
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« Reply #1 on: April 05, 2018, 04:46:59 PM »

My favorite pastime over the last several years has been reading about the Vietnam War. Keeping in mind that I was all of about fourteen when it ended but did grow up on a military base and was aware of everything that was going on at the time.
Many radios like the GRC-19 (T-195/R392), or the GRC-9 were field radios designed for AM operation. Larger tactical sets like the AN/GRC-26 with its T-368 and stacks of R-390 receiver although designed primarily for teletype did also support AM.
With FM radios like the PRC-25/77 or the VRC-12 family of radios intended for short range field use and all the long range voice supported by SSB radios like the PRC-47, PRC-70, PRC-74, AN/GRC-106 and last but not least the ubiquitous Collins KWM-2A cannot see where AM was used. Have read things like where unofficially crews took things like T-368 transmitters and removed the modulator deck, shortened the case and use it as a portable Teletype transmitter so apparently AM was not highly valued.
I know that AFVN operated AM broadcast operations throughout the country and there appears to have been hundreds of AM/CW only AN/GRR-5 receivers that were used for something so somewhere larger AM transmitters must have been used to broadcast to them?
 Large tactical networks were VHF multiplexed and VHF Troposcatter systems like the MRC-85 sets that carried lots of multiplexed telephone channels and early satellite systems like the MSC-44 that linked Vietnam back to Hawaii from outside of Saigon, the center of communications for all of Vietnam.
Saigon also operated HF channels to the Philippians, Okinawa and Bangkok but going to assume they were SSB.
The only place I can think of where AM stood tall was as still is today Aircraft communications being that was all VHF AM. So what I am asking here is if anyone knows of AM operations during the war? Or do we have to go back earlier to Korea?





Nick KG2IR has a wonderful example of the "Angry 19" in his H2.  I'm attaching 3 photos. Nice installation

Al


* GRC 19 Rear cargo area H2.gif (821.35 KB, 1500x997 - viewed 242 times.)

* GRC 19 PS.gif (725.53 KB, 1500x997 - viewed 237 times.)

* H2 Front.gif (708.28 KB, 1500x997 - viewed 202 times.)
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« Reply #2 on: April 06, 2018, 05:16:58 PM »

Quote
The only place I can think of where AM stood tall was as still is today Aircraft communications being that was all VHF AM. So what I am asking here is if anyone knows of AM operations during the war? Or do we have to go back earlier to Korea?


Well I wuz in the Army from 1959 to 1965 as a radio repair man and all around como man. We didn't use AM for anything except for aircraft as you pointed out. Most of the guys that were in WW11 are now gone that were hams and might have known more about the modes used then. I suspect that most communications for ground operations were wide band FM. When I was in Korea (1959-1960) we used FM and CW. All CW was encrypted but at its lowest level as no war was going on in them days. To operate AM when I was in service an operator had to know how to set it up as most transmitters weren't plug & play, so therefore more training may have been necessary at least with the equipment that we had. We still had some vintage WW11 equipment in use and as a matter of fact, there were some BC-610's in Vietnam. A friend of mine had a BC-610 set up on what would have been our state side AM band broadcasting frequencies, broadcasting music and other talk shows that was of interest to the troops out of Saigon. He told me that every few days he had to reset the OSC back to the AM frequency they were using due to the drift that BC-610's are infamously known for. I wonder if that transmitter is still over there? 
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« Reply #3 on: April 06, 2018, 07:00:31 PM »

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The only place I can think of where AM stood tall was as still is today Aircraft communications being that was all VHF AM. So what I am asking here is if anyone knows of AM operations during the war? Or do we have to go back earlier to Korea?


A friend of mine had a BC-610 set up on what would have been our state side AM band broadcasting frequencies, broadcasting music and other talk shows that was of interest to the troops out of Saigon. He told me that every few days he had to reset the OSC back to the AM frequency they were using due to the drift that BC-610's are infamously known for. I wonder if that transmitter is still over there? 

His name wasn't Adrian Cronauer was it?

Tongue semi in cheek.  Good morning Vietnam was loosely based upon the real Adrian Cronauer.

--Shane
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« Reply #4 on: April 07, 2018, 09:07:40 PM »

No Shane, he is not. His name is Jack Dobbs SK WB6AXW known to his friends as the BIG AXW. He was a big overweight dude that I could never forget. I met him while stationed at Ft Hood, Texas. He was with a different company than I but we were both como men. One of the many things about him that I'll never forget is when we would do our morning PT drills and would have to run about a mile everyday and he was always dead last coming into the main exercise area but always made it.

I received many letters from him stationed in Vietnam and one was him setting in front of the Collins Gold Dust twins and telling me of all the fun he was having with it. I lost touch with him and thought perhaps that he was killed over there. I sort of got that idea since I met a fellow soldier who said that the last time he saw Jack was when he was going over a fence. I thought he was in the area of an explosion and therefor my dim view of his possible demise.

I got involved with computers in 1999 and was able to find him located in San Diego so I gave him a call, the  funny thing was that I was in San Diego in 1997 and had I known that he was living there, I would have stopped by to see him. We had many 10 meter qso's catching up on the past. He was forced to retire from his job in broadcasting due to diabetes that had affected him to the point where he had one of his legs amputated and the other was cut off at his foot. Unfortunately he succumbed to that dreaded diseases and therefore, we never had an eyeball QSO?  In the end I can say that he was a great man who served his country but caught the short end of the stick health wise.  He was a large man with even a larger smile and that's how I will remember him


* WB6AXW 1965.JPG (24.07 KB, 369x283 - viewed 222 times.)
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« Reply #5 on: April 09, 2018, 10:25:24 AM »

What a VERY small world.

I grew up listening to the radio station he was employed at, KCBQ.

San Diego brat, born and raised (mostly).

He was very well known locally and very well respected in the ham radio community.  Always willing to help.

Just wow!

As an aside, one of the old KCBQ standby xmitters has been moved to the 75 ghetto.

--Shane
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« Reply #6 on: April 09, 2018, 04:23:29 PM »

Yes there was a lot to say about old Jack! Did you actually ever meet him Shane?

Sorry Ray for hijacking your thread! Sometimes I get carried away Wink Wink
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« Reply #7 on: April 09, 2018, 10:08:27 PM »

We had a local swap meet, 'The Ham Swapmeet' in Lakeside, CA.  I had run into him a couple times.  I was a CBer kid then, and would always get the 'when you gonna get your ticket' speech.  Should have listened.

--Shane
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KA3EKH
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« Reply #8 on: April 10, 2018, 04:09:52 PM »

No problem, wanted to get activity going in this section anyway. I remember as a kid back in the seventies growing up on base and how not too many talked about it back then and even less in the years after the war. Most Vietnam veterans donít ever talk about there service unlike the older WW2 veterans.
Donít know why, maybe it was seeing things Collins KWM-2A, R-390 and vehicles like the M151 in service at that time that I have spent the last several years collecting, restoring and playing around with this stuff? Went so far as to locate and restore an AN/FR-38 frequency counter after seeing one in operation at the MARS station back in the seventies. Have a YouTube video of it at:
https://www.youtube.com/watch?v=3ka1wwvex5o


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KA2DZT
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« Reply #9 on: April 10, 2018, 10:08:17 PM »

I had one of those monster freq counters.  I reduce the whole thing to parts and pieces.  Still have some of the sub sections.  Used one in the late 1960s when I worked at Westinghouse Electric.

Fred
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« Reply #10 on: April 16, 2018, 08:42:06 PM »

My father was a commo chief in a 40 MM antiaircraft unit in Europe.  From what he said, their main radio was the Command Set: ARC-5  and SCR-274N, and mostly on voice [AM], since they didn't have any CW ops assigned most of the time.  They used wire internal commo when  they could; much harder for the other side to listen to.  Said he thought there was some FM used, but he never saw any of the rigs.  Of course, they were attached to the Army Air Force most of the time and the Command Sets were the obvious choice.
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73,  Mitch

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« Reply #11 on: April 20, 2018, 02:16:28 PM »

Quote
Most Vietnam veterans donít ever talk about their service unlike the older WW2 veterans.

The reason most Vietnam vets decine to talk about their service is because of how unpopular that war was! Our country was in great turmoil then as it is now but for other reasons. People would be waiting for returning vets from Vietnam and spit at them at the as they departed.
 
As a former soldier I can tell you that no one wants to go off to war justified or not. I had been thanked many times by complete strangers for my service once they found out that I had served. I take their thanks and mentally transfer it to the people who really deserved it particularly those who served in Vietnam....... 
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