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[RFI] RFI to transceiver

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Subject: [RFI] RFI to transceiver
From: Pete Smith <n4zr@contesting.com> (Pete Smith)
Date: Thu, 21 Oct 1999 09:10:57 -0400
Greetings, all.  I just recabled my shack to make the coax cable runs from
TS-930 to SB-220 and SB-220 to entry bulkhead no longer than necessary, and
to clean up a number of accessory cables.  Now, to my chagrin, I find I'm
getting RF into my transceiver.

Symptoms -- happens only on 80m, and only when my 4-element array is
pointed toward my chack (from 200 ft away).  Happens only with QRO.  The
frequency display on the transceiver flashes in time with keying.  Does not
seem to affect frequency control or other aspects of the radio's performance  

I plan to go through the station this weekend, checking the integrity of
grounds, etc. (it's on the second floor, so RF grounding, in particular, is
always suspect, but I didn't change the ground connection's length from
before, when there was no inward RFI.

My suspicion is that there are common mode currents on the jacket of my
coax, and that changing the length of the interconnecting cables may have
caused a voltage or current peak to occur at the transceiver.  Is that
plausible?  If so, would a coax common mode choke, either between
transceiver and amp or at the entry bulkhead, make sense?  Any other ideas
about things to focus on? 

73,  Pete N4ZR
Sometimes a tower is just a tower

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