[Elecraft] circuit breaker

[Ron D'Eau Claire]

The normal underlying cause for the breaker to open is over-current. That's
a 20A breaker that protects only the KPA3 100 watt amplifier module. The
first thing I'd do is check the current drain from your power supply on the
band where you experienced the problem. First set the power to 10 watts so
the KPA3 is bypassed and note the total current drain key down. Now crank up
the power and see if the part used by the KPA3 is pushing 20A. For example,
if your total current at 10 W was 3A, does the total at 100 watts approach
23A? IF so, the breaker was simply doing its job. Note that circuit breakers
are not precision devices so it may trip a couple of amperes one way or the
other from 20A. 

A primary reason for excessive KPA3 current is a high SWR on your antenna
system. The higher the SWR, the less efficient the KPA3 becomes and the more
current it has to draw to produce the power. 

A defective breaker can also start tripping at lower currents. 

73, Ron AC7AC

-----Original Message-----
From: Elecraft [mailto:elecraft-bounces at mailman.qth.net] On Behalf Of todd
ruby
Sent: Monday, May 16, 2016 9:08 AM
To: Elecraft Reflector Reflector
Subject: [Elecraft] circuit breaker

Would anyone venture to guess what would cause the circuit breaker to trip
on a K3? Mine did all of a sudden yesterday. Fortunately, my friend
suggested the reset and voila, I am back on the air. But if there is an
underlying cause, I think it would be wise to be aware of it so as to
preclude this episode from repeating. Any thoughts are welcome.

73

todd

WB2ZAB