[ARC5] Starting work on BC-453B

[David Stinson]

Jim Mandaville wrote:

> 1.  What is likely to be causing the oscillation? (I'm suspecting bad
> bypass caps) or voltages too high on the R.F. stage).
Most definately bad caps.  You can get around this problem
without changing the caps by running both filaments and B+
at 24 VDC.  An amplified speaker will give you plenty of audio-
the are available and cheap from any computer surplus outlet.
All control and audio connections are available from the 
connector on the back skirt- no need to drill anything.

> 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.

The caps mounted in the round tubs on the side are ALL bad- I promise. 
Those that are not leaking now will be leaking 
after several hours at full B+.  This will cause the failure of 
other componants when they short.  If you run the rig at low B+,
it is likely you'll not have to change any of them, or at most
one or two.

73 DE Dave AB5S