Richard S. Lindzen wrote:
I'm running the K3 with an Ameritron AL800 and a Steppir 3 element with
40m dipole add-on. I have a severe though intermittent feedback problem
on 40m that I did not have with an Icom 751a. The feedback only occurs
when I'm using the amp (even with very low drive). I've common core
choked virtually every lead with ultimately no luck. I'm using the
Elecraft hand mike. Is there a known problem here? Otherwise, I'll
just keep searching.
There is a so-called "pin 1 problem" in the K3's mic input circuitry. The fix is to jumper
L4 on the front panel board and L7 on the KIO3. These are RF chokes in the mic return lines.
I have not done this yet myself, since I am a CW guy! But I'm sure Elecraft support can
provide you with detailed instructions for doing this if needed. The mod has solved RF
feedback problems for several K3 owners.
--
73,
Vic, K2VCO
Fresno CA
http://www.qsl.net/k2vco
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