1. Elecraft-K3@groups.io

Re: K3-S RF output pulses while TX in FT8

Mike Flowers
 

My soundcard will produce a pulsing output tone at certain frequencies and under certain RF power out and WSJT-X Pwr drive levels, into an antenna or a dummy load.   A change to any of these parameters seems to clear it up.

 

- 73 and good DX de Mike, K6MKF, NCDXC Secretary

 

From: Elecraft-K3@groups.io <Elecraft-K3@groups.io> On Behalf Of McClain Richard
Sent: Friday, May 15, 2020 14:52
To: Elecraft-K3@groups.io
Subject: [Elecraft-K3] K3-S RF output pulses while TX in FT8

 

When I transmit FT8, I can see the P3 (with TX monitor) display shows RF output is modulated or "Pulses". Pattern reminds me of watching AM modulation of a sine wave viewed on oscilloscope.

It does not occur all the time but does occur on any band using either antenna or dummy load. I have done FT8 extensively for 2-3 years, but this issue started a couple of weeks ago. I have carefully checked Owner's manual as well as book by Fred Cady, KE7X. Can't find root cause. Any clues are appreciated. I can document more thoroughly, but want to post a brief comment in case there is an obvious solution to someone else. Thank you. 
Dick, KD4S

Equipment: K3-S S/N 10905 (built in 2018), P3 with TX monitor, WSJT-X version 2.1.2

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