Re: power and mic wiring


Bob Lunsford
 

Original caps are indeed "unobtanium" but replacement caps
are worlds ahead of the old technology. I had a Swan 350
about ten years ago that I bought at a hamfest. Plugged it in
and the power supply caps were beyond saving and one
blew up and it sounded like a shotgun shell going off.

There are some who advise putting a variable AC transformer
in the circuit and bringing it up slowly "to polarize the caps" but
while this may work, better is to do as suggested: Make a list
of the electrolytic caps and plan on replacing them.

Some have suggested putting a 100-250 W lamp i series with
the AC so the AC is limited. Might try it but it is a trial and error
situation where error is most likely and proves to be a waste of
time.

I had a Philco 650 back in the '50s that had a shorted bypase
cap on the power output tube from screen to ground. It was not
an electrolytic. This proves that it could be any cap. The electro-
lytics are polarity sensitve and putting one in backwards as far
as polarity is concerned is like inviting a short and immediate
failure.

Go slow, take your time. Some of those old radios were superb
as was the Philco I had.

Bob — KK5R

--------------------------------------------

On Tue, 1/1/19, Mike Lichtman via Groups.Io <tchrme=aol.com@groups.io> wrote:

Subject: Re: [BITX20] power and mic wiring
To: BITX20@groups.io
Date: Tuesday, January 1, 2019, 8:23 PM

Eiclan,
    On the 30’s radio,
replace all the caps (especially the electrolytics) 
before powering up again or you may burn up the power
transformer. They are usually “unobtanium”. 73 Mike
KF6KXG

Join BITX20@groups.io to automatically receive all group messages.