[ARC5] interesting ?
Michael Hanz
aaf-radio-1 at aafradio.org
Sat Feb 24 08:16:44 EST 2018
On 2/23/2018 11:10 PM, Tim wrote:
> Hi Mike - Interesting stuff....I have an APR-4 with several tuning
> units. It operates on either 115V 400 or 60 cps AC power (plus 28VDC
> for the motor I think) , 60 cps is something I always wondered about.
> For an airborne set anyway.
> Perhaps that was a holdover from the GR Lab instrument design? Or
> maybe for shipboard ESM work?
The original GR P-540 had a power transformer that worked on 60Hz - it
was a test instrument. The derived aircraft variations (SCR-587, ARC,
and ARC-1) used a 28 volt DC supply, with an internal 250volt DC output
dynamotor. By the time the APR-1 and APR-4 rolled around in 1944, they
had changed the specification to 10 watts of 28vdc (tuning motor) and
110 watts of 115vac from 60-1000Hz. They also included an 80vac tap for
our UK brethren, reflecting the combined nature of warfare during the
period. That did allow those receivers' use on a wide variety of
platforms. When the ALR-5 (that included the R-444/APR-4Y mainframe)
was procured, the contract specified a 380Hz lower limit (upper limit
1000Hz), befitting its dedication to aircraft platforms. It also
dropped the wartime 80 volt tap in the power transformer.
73,
- Mike KC4TOS
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