[MRCA] The Radio Sets Were Humming...

[Mike Morrow]

Mark wrote:

>> The "humming" could have been a vibrator power supply, but it
>> was more likely caused by squelch not being fully adjusted on
>> the radio to silence the white noise, or static, coming through
>> the radio.

Robert wrote:

> No, no aircraft radio receiver of that period nor most of them
> (except for the Army's low-band VHF sets after about 1960) had
> any squelch circuit.  They were all MF and/or HF AM/CW sets.
> The "humming" referred to was obviously the receiver dynamotor(s).
> Which in the 8th and 9th AF of the period would have only been in
> the BC-224, BC-348 or SCR-274-N receivers.

There also was no vibrator-powered gear in WWII-era aircraft either.

Some WWII FM ground sets like SCR-508, -608, -808 and the SCR-300 had squelch, but no aircraft sets.  I never head squelch hum before the era of AN/VRC-12 style "new squelch".

Other common WWII airborne dynamotor "hummers" would be found in:

SCR-522 VHF command
SCR-595 or -695 IFF
RC-103  VHF localizer
SCR-269 ADF (external 400Hz inverter)
RC-35   Interphone

There are likely some other dynamotor-powered sets found in B-17 and B-24 aircraft that don't come to mind at the moment.

I agree, Robert...there's no doubt that the song's "hummers" were anything except radio set dynamotors.

Mike / KK5F