[Milsurplus] SCR-288/BC-474

[Nicholas Hopper]

Thank you everyone for the replies.  Well my skills are , well let's say,
lacking in this department. But I'm always up for a challenge!  I will get
some pictures taken and send them out of it.   I'll get to work on the few
items that have been mentioned but I feel I will have to find someone local
to help in testing and troubleshooting this unit.  A great chance to meet
someone and learn at the same time!  But I will at least dig in where I can
at this time and see what I can do.

Nick

-----Original Message-----
From: David Stinson [mailto:arc5 at ix.netcom.com] 
Sent: Tuesday, January 03, 2012 4:06 AM
To: Nicholas Hopper; milsurplus at mailman.qth.net
Subject: Re: [Milsurplus] SCR-288/BC-474

Welcome, Nicholas!
You have a very desireable set there- the GN-44 alone has 
many members reading with envy ;-).  It is a fairly advanced
project for a beginner, but certainly "do-able."  I have two and
use them on the air operating as originally designed.  They
work fine.  I have to get to work this morning but when 
I get home, I and I'm sure many more of our great members 
will see if we can help.  First off- how are your trouble-shooting 
skills and what test equipment do you have?  There are going 
to be some componants that will need replacement.

The popping and noise you hear can have mulitple sources.
It's likely the switch needs cleaning with a compound like
De-Ox-it, but there is also the good possiblity of electrical
leakage through capacitors.  If this is happening, you run 
the risk of damaging other componants to which these are 
connected.  Until we can examine them, I'd advise leaving
the set off.  Also- in your battery replacement design for
the receiver power supply, make sure the B- end is not 
connected to ground.  The reason the audio output 
transformer needed replacing is someone using a receiver 
high voltage supply with the B- grounded, which will 
instantly destroy the original transformer.

Also- you might want to consider removing mods like
that 6C4 stage, which was a needless addition and
which will cause trouble.  Mine modulates just fine 
with the correct microphone.

It will be very helpful if you can take some good 
detail photos of the chassis so we can see its 
condition.  
Got to get to work.  More later.
73 DE Dave AB5S

p.s. First thing- In the middle of the back of the chassis is
a tall, silver can capacitor.  If unchanged, it will have a wire
that runs to the TRANS  REC  switch.  You should disconnect
this wire and move it out of the way.  It's a design error 
that was corrected in an official change order.  More later.




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