I had a lot of helpful responses to my post below a couple of weeks ago. I thought I'd let everybody know how I fixed the problem. Added a Radio Works T-4G Line Isolator at the antenna base connecting its ground strap to a dedicated 8 foot ground rod. Connected the Elecraft K3 ground and the AC ground together at a terminal strip and then led the grounding line (three 12 gauge wires in normal house wiring cable from Home Depot) to a separate ground rod a yard away from the antenna ground rod. Before getting all this to work, I tried a non-grounded line isolator (Radio Works T-4-500) which did not help regardless of all the grounding variations I tried. Also what did not work was connecting the shack ground line to the same ground rod as the antenna choke's ground strap. I guess the ground currents are pretty bad, and need to be shunted off completely isolated.
The original problem was RFI getting into my transmissions out on 20 meter SSB. SSB was fine on all other bands and CW worked fine on all bands. I had a 30 minute 20 meter SSB QSO a couple of days ago and got a great signal and audio report. Thanks again for the suggestions. 73, Ron Gruner K4RHG ---------------------------------------- From: "Ron Gruner" <r...@gruner.com> Sent: Sunday, November 18, 2012 12:59 PM To: elecraft@mailman.qth.net Subject: SSB RF problems on 20 Meters Only I am getting RF interference when SSB on 20 meters on my Elecraft K3. A warble in the audio (with either the speaker or headphones) starts at about 5 watts which gets much worse as I increase power to the point the audio is just a screech. It works fine on CW. I have no problems on other bands both above and below, just 20 meters on SSB. I still get the distortion on the sidetone with audio and RF gain turned to the minimums. My antenna is an Ultimax DXpedition with a buried ground plane and a six foot ground rod attached to the start of the ground plane wiring. I wrapped about 50 turns of #16 stranded around the feed coax close to the antenna junction box as a choke, and also attached a 17.3 foot wire off the ground plane to resonate at 14.15 MHz as a friend suggested. Nothing helped. I've only been licensed since July, so this is all new to me. Thanks for any help. Ron Gruner K4RHG ______________________________________________________________ Elecraft mailing list Home: http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/mmfaq.htm Post: mailto:Elecraft@mailman.qth.net This list hosted by: http://www.qsl.net Please help support this email list: http://www.qsl.net/donate.html