[Elecraft] circuit breaker

Mon May 16 15:30:02 EDT 2016

Todd responded to me off the reflector that he lost all power to the K3 so it wasn’t the 20A breaker. That only controls power to the KPA3. The front panel is still powered and the receiver continues to work. 

I suggested it might be the self-resetting breaker inside the K3. That will turn it off completely. Actually power will still be on the KPA3 module and anything plugged into the 12V external power connector on the K3 rear panel, but the K3 itself will look dead with no front panel lights, receive or other functions until it cools and resets itself. 

I’ve never had an issue with either breaker opening unexpectedly.

73, Ron AC7AC

From: ac5p at sbcglobal.net [mailto:ac5p at sbcglobal.net] 
Sent: Monday, May 16, 2016 12:18 PM
To: Ron D'Eau Claire; 'todd ruby'; 'Elecraft Reflector Reflector'
Subject: Re: [Elecraft] circuit breaker

I believe Todd is referring to the breaker on the K3, not his house panel circuit?

Ron has some good advice, but I wonder how common this circuit breaker operates?  

I looked thru my manual for more info on it.  The block diagram shows it as a 25A fuse,

text and device indicate 20A circuit breaker, but NO  info on the type operating curve, or current vs. time for minimum trip?

I have a 10A circuit breaker on my 40Ahr battery supply and it has never tripped.  It is a thermal time delay like most house breakers.

Anyone out there have any clue?   Wayne?      

Mike  AC5P

On Monday, May 16, 2016 12:28 PM, Ron D'Eau Claire <ron at cobi.biz> wrote:

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

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