[Elecraft] RF feedback? only when using KXPA100

[Edward R Cole]

Concur on suspecting cables as first step for most problems.  Also 
suspect the meter that measures the signal/voltage/current/etc. Or 
other items in the line.

I ran into a similar issue using an antenna tuner on 2m.  I had just 
put up a 11-element yagi (not real high but equivalent to the 
vertical previously used).  I could hardly hear my neighbor on 2m-SSB 
only 15 miles away.  More interestingly he reported my signal as 
low...hmm.  I switched back to the vertical and signals in both 
direction jumped up in strength...double hmm!

OK the yagi had not been in service for a couple years and I was 
unable to make any tests before it was put up on another tower.  SWR 
was close to marginal so I inserted my 2m antenna tuner and that 
fixed the SWR.  I checked power on each side of the tuner and it was 
about the same ( a little lower on output).  Soooo I removed the 
tuner and power indicated went from 110w to 100w but the signal 
jumped in both directions.  Note to self: "leave this tuner on the 
dusty shelf".

The SWR is about 1.8 without and tuner but the 100w amplifier is 
happy (no fold back) and signal are much better on both ends of the 
circuit (S0 jumped to S3).  Guess that tuner is very lossy 
(MFJ-921).  Of course MFJ means "mighty fine junk" <smile>

73, Ed - KL7UW
   http://www.kl7uw.com
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