[ARC5] Re volume control

[Brian A Clarke]

Hi Mike,

Good to cross swords with you again.

>From all the manuals and all the installations I've seen, the interphone
amplifier
was used as an intercom, rather than as an audio amplifier for the Command
series receivers. Perhaps the RNZAF and the RAAF developed their own
practices that differed from their suppliers', but the ARC-5 and SCR-274-N
manuals I have collected from the USA show no interphone amplifiers in
aircraft installations.

Re AVC in Command sets - sure the SCR-274-N series used grid
rectification of the RF voltage from the second IF as feedback applied to
the RF amplifier and first IF amplifier as the means of achieving AVC,
while the later ARC-5 actually used a diode for producing a dc bias -
but it was hardly any more sophisticated. Already by that time [late
WWII], most British HF sets, AFAIK, had delayed AVC - Murphy,
Racal, Pye, Plessey, Marconi.

My images of the J-22/ARC-5 in the 1944 NAVAER 08-5Q-95
manual show no volume control. In fact, none of the J-boxes in this
manual shows a volume control.

I have seen the Station boxes - but they were used with the SCR-522,
as I recall. I have not seen them specified for use with ARC-5 or
SCR-274-N. Perhaps there were off-the-book lashups that Americans
could do because the parts were more readily available.

73 de Brian, VK2GCE.