[R-390] Cap Question

[Cecil Acuff]

Looks to me like they have already been replaced.  Someone may have just 
used what was on hand.  Looking at the solder joints and the insulating 
tubing it looks like recent (relative) work.  Maybe from a Mil. Overhaul.

Cecil...

----- Original Message ----- 
From: "Barry" <n4buq at aol.com>
To: <R-390 at mailman.qth.net>
Sent: Wednesday, March 16, 2005 9:24 AM
Subject: [R-390] Cap Question


> Looking at the caps in my "new" R390A RF deck, I'm considering replacing 
> the
> three brown beauties in it.  I'm curious, though, about two of them.  They
> are used in the heater thermostat circuit of the crystal oscillator can. 
> In
> the picture referenced below (thanks, Don), they are the big, yellow ones 
> in
> the upper right corner:
>
> http://militaryradio.com/Images/390rfd.jpg
>
> The heater voltage is 6.3VAC and I'm wondering why the designers used 400V
> or better caps here.  Is this necessary because the noise spikes are
> considerably larger than 6.3V or is it possible that these were just handy
> since there were so many other 0.1mfd @ 400V caps used in other places in
> the radio.
>
> Any comments?
>
> Thanks,
>
> Barry(III) - N4BUQ
>
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