[Elecraft] SSB RF problems on 20 Meters Only

[Gary K9GS]

Hello Ron,

I think you have one of these antennas:

http://www.ultimax-antennas.com/ACCESSORRIES.html

Being an end -fed antenna I almost guarantee you have RF coming back 
into the shack on the outside of the coax shield.  To fix this you need 
a common-mode choke.  Google K9YC and you can find all kinds of 
information on building one.  You'll want to use #31 ferrite cores.

Wrapping 50 turns of stranded wire around the coax makes absolutely no 
sense.  You didn't say what the stranded wire is connected to but it 
could actually be contributing to your problem.


On 11/18/2012 11:59 AM, Ron Gruner wrote:
> 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
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-- 


73,

Gary K9GS

Greater Milwaukee DX Association: http://www.gmdxa.org
Society of Midwest Contesters: http://www.w9smc.com
CW Ops #1032   http://www.cwops.org

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