[Elecraft] K3: Very distorted audio on transmit but only on 20m and only with the KPA500 on

[Stewart]

Tom,
Check that your MKII has the capacitor modification that decouples the USB cable 
shield. If not,  RF on the cable can cause audio problems. Details are on the 
MicroHam site.

73
Stewart G3RXQ

On Tue, 11 Mar 2014 17:58:00 -0400, tomb18 at videotron.ca wrote:
> Ok, thanks, that's what I thought. A little more complicated since I have a 
MicroHam microkeyer II in the circuit but probably fixable.
>
> 73's Tom
>
> On 3/11/14, "Donehrlich at q.com" <Donehrlich at q.com> wrote:
>> Almost certainly RF getting into the mic circuit. Try a different mic .. or 
use the rear panel mic connector as a check. You probably have high SWR into the 
antenna feedline (or coax) after the tuner on 20 meters and that is why you only 
see problem on 20M. High SWR on the feedline (Note: your rig can be seeing low 
swr .. it is AFTER the tuner where you have high SWR) results in high current or 
high voltage that then couples into other shack wiring. Of course, the higher 
power from the KPA500 pushes those voltages/currents to levels that are more 
likely to cause problems. Been there, done that .. many times.
>>
>> Don K7FJ
>>
>>
>> >Ok,
>> >
>> >So my audio is quite distorted as I can hear in my headphones with the 
monitor. But this only happens on 20m and only with the KPA500 in operate.
>> >Sound like RF? or is something else going on?
>> >
>> >
>> >Thanks
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