[RFI] Coax blues

Scott Holisky sholisky at gmail.com
Sat May 1 22:33:01 PDT 2010

On the weekends I like to fire up the rig on 30 meters and do a bit of WSPR
mode. It's good fun to see how many stations you can hear and be heard from
around the world.

I noticed a few weeks ago that there was a substantial increase in the noise
floor, to the point that I was having difficulty copying signals that my
locals reported as quite strong... The light went on, the problem only is
audible on one radio. Today I was changing antenna feeds and disconnect the
rig from the antenna switch, the noise suddenly increased!

On this rig the short 10' jumper is "Alpha RG-58" something I picked up on a
dismantle job. Should of known better. My recent playing with a new matching
transformer for my K9AY loop caused me to grab the old cable from the rig
and put this one on.

I replace it with an identical length of RG-8U and found no noise.

The lesson (oh how many times must I relearn) is to always be suspicious of
everything when tracking down qrn.

73 Scott

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