Bill,
That is not normal - BUT -
Before I can offer a single suggestion, can you say whether your KPA100
is the older T/R switch design or is it a KPA100 that shipped after Nov
2006? If it is the older design, has it been updated with the
KPA100UPKT - and if it has been updated, was C31 also changed to 0.22 uf?
*If* you have the older T/R switch design, there is a possibility of a
parasitic that can show up during tuning, particularly on 40 meters.
With the new design, *if* C31 was not changed to 0.22 uf, there is a
possibility of a low frequency oscillation that shows up when operating
on 160 or 80 and sometimes on 40 meters. It might be possible for an
oscillation to create a sufficiently high RF voltage to zap the diodes
during a tuning cycle of the KAT100. (Note that there are many 'ifs'
here, thus the reason for the questions to be answered - it depends on
the level of your KPA100).
If your KPA100 is the older design, I suggest the KPA100UPKT may cure
the diode zapping, but if you already have the update (including the new
C31), then there is some other problem.
73,
Don W3FPR
Bill Carpenter wrote:
Hi all,
Since adding a KAT100 to my K2/100 about a month ago D16 and D17 in
the KPA100 have blown 3 times. The first time I thought it was caused
by antenna static buildup during a blizzard but the last 2 times it
happened as the tuner was attempting to tune an antenna. Could there
be problem with the tuner that is causing this? Everything is well
grounded and the antennas are not bedsprings but a G5RV and twin sloper.
I'm getting real tired of replacing those diodes!
73,
Bill NZ0T
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