[ARC5] Re: ARC-5 repair

[Mike Hanz]

David Stinson wrote:

> 28 volts works fine on my Command Sets. 90 volts gets you in a better 
> place on the tube curves, and I think that's why most other boatanchor 
> receivers seem to need around that much.  That our sets will work with 
> 28 volts when others need about 90 or so got me to thinking:
> Perhaps the A.R.C. engineers were even more brilliant than we know, 
> because I'd bet a donut and coffee they "tweeked" the design so the 
> sets would keep working into the aircraft interphone,
> which would provide an audio boost, even if the dynamotors went belly-up.


Certainly true of the later interphone amps like the AIC-4, but, alas, 
not true of the earlier ones like the RC-36 and AIC-2.  They had the 
receiver output fed directly into the earphones of anyone who switched 
to the command or liaison receiver positions.  Making the change to feed 
the receiver output to the amplifier isn't a huge modification, though.  
I rigged one similar alternative just changing a couple of wires in the 
BC-366/BC-1366 to allow a carbon microphone to be fed into the amp for 
those cases where the mike was somewhat cemented from moisture and age 
(as many of them are).  Works a treat...Steve KB4DMF used it on the 
SCR-274N set he put together for the Collins Amateur Radio Club museum 
event a couple of years ago.  Those minor changes are shown at 
http://aafradio.org/docs/RC-36.html

73,
Mike  KC4TOS