[Milsurplus] SCR-288 ( BC-474 ) Change 1, May 1944

[David Stinson]

A tip to all who might want to tackle SCR-288:
There is an electrolytic cap on the B+
buss, originally there to smooth-out
the generator voltage.  It charges and
when you switch to "Transmit," it
discharges through the T/R switch
contact to the TX B+ buss.  This
causes a spark that will eventually
eat-up the T/R switch contact.
Just disconnecting this cap isn't
a complete solution, since the output
cap on the usually-built power supply
can do the same thing if it's large.
Years ago, there were some suggested
solutions to this design flaw.  Any of
those worthy folks still here to comment?
IIRC, I put an output choke in my supply
which stopped this sparking.  Been a lot
of years.  I should break mine back out.
I have the genny, the original antenna and
counterpoise, etc.  The only thing I lack
is the cases/canvas, which are likely extinct.

GL OM DE Dave AB5S


On 10/30/2024 7:09 PM, Al Klase wrote:
> Thanks Hue,
>
> SCR-288 is one of my favorite radios.
> See my webpage: http://www.skywaves.ar88.net/mil/SCR-288/SCR-288.html
>
> VY 73,
> AL
>
>
> On 10/30/2024 5:16 PM, Hubert Miller wrote:
>>
>> Let’s try that again.
>>
>>
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> -- 
> ARK Sig Block Al Klase - N3FRQ
> Jersey City, NJ
> http://www.skywaves.ar88.net/
>
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