HP-23 Capacitors & Breakers.

[Stewart D. Lyon]

Hi folks:
There seems to be a rash of HP-23 power supply problems where the breaker is
tripping under moderate loads.  The suspect is the 125/450 capacitors.

MAYBE it's the circuit breaker!

I recently bought a new (to me) HP-23A to power my HX-1681.  As soon as i
loaded up the rig, the circuit breaker started popping.  I, like everyone
else, replaced the 125uf caps in the 800V circuit with 330uf/450V units.
Didn't help!  I then replaced the circuit breaker (which was rated at 2.75A)
with a new 3.5A one and now the power supply is able to deliver well over
250 mils.  These breakers are not easy to find.  I was able to talk a "big
minimum order" distributer out of one as a sample.  Try an appliance parts
store - they look like the ones in a garbage disposal and probably other things.

I also found the panel meter is WAY off on the HX-1681.  When it reads 200
mils of cathode current, the actual plate current is close to 300 mils. I
fixed it by changing R4 from 6.8K to 5.6K. (I'll bet when Joe Lutz gets
around to the HX-1681, there'll be a service bulletin on this.)


Hope this saves somebody some grief.  Stu -- W6CUX

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