Bill,
That is classic behavior when the KPA100 wattmeter diodes are zapped.
Since the most common failure cause is a static (lightning) surge from
the antenna, you may want to consider replacing the ones in the KAT100
at the same time. The diodes are 1N5711s and in the KPA100 are D16 and
D17 (near the SO239 jack), and the diodes in the KAT100 are D1 and D2.
As explanation for the behavior, the K2 power control loop senses power
at the output with the wattmeters - if there is zero power out reported,
the controls drive harder - so you have a base K2 trying to drive as
hard as possible and the resulting output power is the maximum that can
be produced on any given band. In other words, the wattmeter must be
working for the K2 to control the output power - that is the sensing
element.
73,
Don W3FPR
Bill Carpenter wrote:
After some investigation I found that the braid of the coax for the
Aux RF had frayed at the KPA100 board to just a couple of strands.
Hoping this was the problem I repaired it but no change. This all
seems to be caused by the K2 power control being all or none with no
intermediate settings. In low power as I turn the knob clockwise it
goes from minimal power to full QRP of about 12 watts suddenly and
when the high power comes on it jumps to full output. How do I
approach this problem? Is it ALC related?
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