SCR-508 etc and SCR-608 etc intercommunication

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Gary Kennedy
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SCR-508 etc and SCR-608 etc intercommunication

Post by Gary Kennedy » 03 Jul 2020 19:02

I've been educating myself on radio equipment over the last few years and have recently been looking at certain US Army SCR FM sets.

The SCR-508 (two receivers, one transmitter) had a frequency range of 20.0 to 27.9 megacycles (80 channels). The same went for the related SCR-528 (one less receiver) and SCR-538 (single receiver only) which used the same transmitter and receiver equipment. The same frequency range was also used on the SCR-510 and related SCR-509 (dry cell battery, manpack SCR-510).

The SCR-608 (2 receivers, 1 transmitter) had a frequency range of 27.0 to 38.9 megacycles (120 channels). The same went for the related SCR-628 (one less receiver). The same frequency range was also used on the SCR-610 and SCR-609 (dry cell battery, manpack SCR-610).

The SCR-500 type sets above were used by the Armored Force, and the SCR-600 type sets above by the Field Artillery. I have always understood that the Armd Force and FA sets could not communicate with one another because they used different frequency ranges. However, there is an overlap of 0.9mc at the end of the SCR-508 range and the start of the SCR-608 range.

Was there then a possibility that an SCR-508 could be put on a frequency shared with an SCR-608, and so on, or was there another reason that meant this overlap could not be used?

Gary

wwilson
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Re: SCR-508 etc and SCR-608 etc intercommunication

Post by wwilson » 04 Jul 2020 06:20

Hi Gary,

Technically, it sounds as if the overlap range could have been used for direct communication. The sets are described as similar except for the frequency ranges used.

Without checking, I would guess the forward observers had both sets, and could communicate with both forces.

Gary Kennedy
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Posts: 848
Joined: 28 Mar 2012 18:56

Re: SCR-508 etc and SCR-608 etc intercommunication

Post by Gary Kennedy » 04 Jul 2020 14:38

Yes, it does seem there was a small window for the 508 and 608 to talk to one another.

There's a version of the March 1943 TM (11-600) for the SCR-508, etc, on Google books as a free download. It does list the 508 as compatible with the 608, 628 and 610. The postwar version of the same manual available on the radionerds site doesn't do, but does shows the overlap in a diagram.

I think the most telling description comes in one of the ETO General Board reports, study no.63, Field Artillery Communications, page 33 refers.

"When armored divisions were supported it was necessary to borrow an SCR-508 for group fire direction or to make use of the overlap in channels between the SCR-608 and SCR-508. In paragraph 35a it was shown that this overlap was only between 27.0 and 27.9 megacycles, allowing only ten channels on each set which can be used. These were found to be inadequate with the overlap band being very badly crowded. The issue of SCR-508 radios to all (Field Artllery) group headquarters would permit any such unit to support armored units at any time with the desired flexibility of radio communications".

I think it was just that I'd seen the comment the two types of sets 'couldn't' net together so often, I was surprised to see that, technically at least, they could. Practicality would appear to have been the main issue.

Gary

wwilson
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Posts: 93
Joined: 29 Sep 2012 08:33

Re: SCR-508 etc and SCR-608 etc intercommunication

Post by wwilson » 04 Jul 2020 17:26

Practicality is a good take, I'd say.

I recall being surprised how narrow the frontage was for a U.S. armored division in Alsace in 1945. The range on those sets ranged far beyond typical divisional frontages, so those 10 channels that were available might have been a choice resource.

I wonder if the overall lack of overlap was problematic when tank and TD battalions were employed in an indirect fire role.

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