[Elecraft] question hi current/kpa out of control

[Ron D'Eau Claire]

The internal fuse and reverse polarity protection diodes that protects the
K3 does NOT protect the KPA3, so you probably blew the KPA3 finals and will
need replacements. 

In the meantime, you can run the K3 at 10 watts. When you increase power
beyond about 12 watts, the KPA3 switches on putting a dead short on the +12V
line. The K3 jumps up to full drive because it's trying to get 100 watts out
of a dead KPA3. Remember, the K3 POWER control "requests" a power level from
the rig, and then increases power until the power monitoring circuit at the
output agrees that the requested power is being delivered. 

73, Ron AC7AC


-----Original Message-----
From: elecraft-bounces at mailman.qth.net
[mailto:elecraft-bounces at mailman.qth.net] On Behalf Of David Eckert
Sent: Sunday, August 11, 2013 3:54 PM
To: Elecraft at mailman.qth.net
Subject: [Elecraft] question hi current/kpa out of control

I really screwed up and reversed polarity to the dc power supply


turned on power supply but NOT radio
surge in current then 20 amp breaker in k3 poped  I reset it amazingly k3
still works but something is wrong with the KPA3 or the PAI/O controller
gives hi current if try to bring power above 12 w will drive KPA 500 to
about 200 w with 12w if you try to increase power beyond 12 w hi current
displays and KPA 500 is quickly overdriven as if the KPA3 is out of control
increasing power in large increments
(KPA500 is usually driven at about 20 w)


is this a computer glitch i can fix or do i need a new KPA3 or PA I/O
module?


Dave  KB8V