[ARC5] Starting work on BC-453B

[Tino Zottola]

Hello Jim,

The secret to 80% of boat anchor repairs is usually
defective capacitors. In the BC-45x series, it was
standard practice to replace all paper and
electroylitic capacitors after every 10 years of
service. I have several reconditioned BC-45x units
that had all the can capacitors on the inner sides of
the chassis walls replaced in the mid-1950's.
Unwanted regeneration is usually caused by an open
screen and/or plate capacitor.

I would not operate your radio at the regular B+
values of 250 volts with the original paper &
electroylitic caps in place. Your power supply and/or
capacitors can be severly damaged. I heard these
radios can be operated with B+ of 25 volts. Never
tried it myself, but I heard it worked successfully
for many people who do not want to replace all the
caps and want to operate the radios.

Good Luck

Tino, VE2GCE


--- Jim Mandaville <zygo@azstarnet.com> wrote:
> Greetings to the group from a new listserve
> subscriber.  Hoping someone
> can give me some advice on the following questions:
> 
> I'm starting work on a recently acquired,
> non-modified, BC-453B.  The
> receiver works, although the set regenerates and
> oscillates at some
> settings of the gain control and antenna tuning cap.
> (I assume it's the
> RF stage that is oscillating.  Changing tubes had no
> effect).  I'm using
> B+ of 253 v. (measured under full receiver load that
> runs 47 mA).
> 
> Questions:
> 
> 1.  What is likely to be causing the oscillation?
> (I'm suspecting bad
> bypass caps) or voltages too high on the R.F.
> stage).
> 
> 2.  Is 47 mA about the right current draw, or does
> this indicate leaky
> caps?
> 
> 3.  What caps should I check as most likely to be
> leaky (I'm assuming
> the ones that handle plate or screen voltages or
> those in the input
> filter.
> 
> Thanks and regards,
> 
> Jim Mandaville, KF7A, Tucson, AZ
> 
> 
> _______________________________________________
> ARC5 mailing list
> ARC5@mailman.qth.net
> http://mailman.qth.net/mailman/listinfo/arc5


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