[Elecraft] KAT100 Problem

[richardjwiltgen at aol.com]

I have encountered difficulty with the KAT100.  I am pretty sure the problem resulted from RF feedback in the shack from a Zero-Five flagpole antenna with an unun at its base, an ugly balun with Polyphaser ground after 80 feet of coax prior to entry into the shack, and a Balun Designs isolation balun following the 20 feet or so of coax that enters the shack.  The isolation balun is inside the shack for stealth reasons because of a very intrusive HOA.  Thae KAT100 would not tune the antenna or a dry dummy load on 20 meters. It will indicate a high SWR and the K2 registers a hot power amplifier. If I run it for a while, the RF gets into the radio and the other bands may be affected.  As a consequence, I will eventually move the isolation balun between the KAT100 and the K2/100 and place another one on the line that leads into the shack.  I tested the components as stipulated in the manual.  When I switch from C5 to C6, the SWR jumps from 2.5 to off scale (9.9) on 20 meters and 1.4 to 7.0 on  40 meters.  Based on the knowledge and past experience of others,  does it seem reasonable to assume that C6 is defective and the cause of the problem?  Many thanks beforehand for any advice you folks have to offer.  Vy 73, Dick, K8RBW.