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[RFI] CATV RFI, Both Ways

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Subject: [RFI] CATV RFI, Both Ways
From: dgsvetan@collins.rockwell.com (dgsvetan@collins.rockwell.com)
Date: Tue, 31 Oct 2000 08:45:53 -0600

The present discussion regarding CATV system RFI brings to mind a point
worth noting.  A few years ago, the buried CATV system in my former
neighborhood was leaking badly, with sync pulse buzzes wiping out much of
the 2m FM band (including a repeater I had been monitoring on 145.25).
Then along came the January VHF Contest, and I fired up my 50W rigs on FM
and SSB for the contest, starting promptly at noon (or 1 pm, whichever)
local time.  I operated for about 8 or 9 hours straight on Saturday, with
few problems at the SSB end of the band (below the CATV carrier), but
problems working some stations on FM simplex if the sync pulses were just
right.  By mid-evening on Saturday, the sync buzzes were gone and all day
Sunday was clear.  However, they returned the following Tuesday.

My conclusion from all of this was that my RF pounded the CATV amplifier(s)
somewhere downstream and the cable company probably got bombarded with
complaints.  (No, neither my doorbell nor telephone rang.)  My "clear
communication" on Saturday evening and Sunday was due, I believe, to them
either killing the channel completely or making a quick, but very
temporary, fix that didn't last.  I continued my normal, extensive 2m
operating schedule for several months, and by Spring, the buzzes were gone
for good.  Since I was not a subscriber to the cable system, I don't know
if they moved the channel or actually fixed the leak, but whatever was
done, was effective.

KG0US has the right idea about identifying the carrier and sound
frequencies.  In my case, a walk to the back yard (with HT in hand), where
the CATV was buried in the utility easement, confirmed that the leak was at
some connection pedestal down the street.  The leak was not at the pedestal
nearest my house, but the carrier was S9+ on the HT as I walked toward the
next one down;  unfortunately, fencing and shrubs prevented me from getting
to that one to confirm if it was the culprit.  If the leak was actually
fixed, it was done while I was at work so no clue as to what they actually

Best luck to others with similar problems.  May you have a cable company
with someone on staff who knows how to spell "EMC".

73, Dale

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