[Elecraft] Newly Built KPA500 Acting Strange

[Carl Jón Denbow]

OK, after Tim, M0AFJ, informed me that the amp needed to have fuses, and 
I dutifully installed same, everything seemed fine for a little while.  
Thanks, Tim, for the heads up.  At that point I tried it on several 
different bands into a dummy load and into the ether and was getting 500 
watts out.  Then, I decided to put a watt meter inline to get a more 
accurate assessment of wattage and instead I got really low output 
readings on several transmissions and then zero.  I then took the watt 
meter out of line and now I have the following phenomenon:  1. In bypass 
mode I get out full wattage -- 45 watts from rig, but the KPA500 says 
it's 35.  The rig's SWR meter registers very low SWR.  A KAT500 is doing 
the antenna tuning after RF passes through the KPA500.  2. If I take the 
KPA500 out of bypass into operating mode, output drops to zero, SWR goes 
sky high, and KAT500 can't tune it.   Seems it must be a short of some 
time that's somewhere in the amp circuit and not in the bypass path.  
Any idea where to start to trouble shooting this?  The strange thing is 
the KPA500 worked FB for the first ten minutes of its life.

Tnxs for any suggestions.

73,

Carl
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Carl Jón Denbow, N8VZ

17 Coventry Lane
Athens, Ohio 45701-3718
EM89wh

http://www.n8vz.com
carl at n8vz.com
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