Jim's comments really hit home with me. I think I have said this before on
this reflector, but it was a few years ago, so maybe worth repeating:
When I lived in northern IL prior to 2000, I was in a subdivision that had
buried cable service, but I was not a subscriber. I began to have QRM on
145.25 and other nearby freqs, and sniffing around the cable easement area
with a 2m HT proved that the sigs were leakage from the cable system. I
learned this just prior to a VHF contest weekend.
Well, I worked the contest, using both FM and SSB on 2m (at power levels of
50 to 150 watts). By Saturday night, the QRM on 145.25 was gone, as were
other sigs from other CATV channels that were below or above the 2m ham
band. A few days later, there was a CATV service truck in the neighborhood
and a guy was going around scratching his head and looking confused. He
did go the pedestal nearest my house and did some sort of work (probably
tightening and/or replacing connectors). He then left. After he was gone,
I took the HT back out to there and I could only hear faint noise on 145.25
and the other close-by freqs. My problems at the house were gone. I
concluded that they must have killed the system when it got hit with heavy
RF during the contest, as I suspect that booster line amps got saturated.
NO further issues with that system.
73,
Dale Svetanoff, WA9ENA
Sr EMC Engineer
E-N-A Systems, LLC
Specializing in shielding applications, system grounding, and lightning
protection
> [Original Message]
> From: Jim Brown <jim@audiosystemsgroup.com>
> To: <rfi@contesting.com>
> Date: 11/1/2012 10:29:21
> Subject: Re: [RFI] rfi problem
>
> On 11/1/2012 4:34 AM, Pete Smith N4ZR wrote:
> > There are specific FCC requirements for signal "egress", so if you can
> > identify the frequency with a cable TV channel, and pin it on them,
> > then they are indeed required to fix it.
>
> One reliable frequency to look for egress is around 145.25, which is the
> frequency of the picture carrier of one the analog channels. If there's
> egress, you'll hear a buzzy carrier here, and you can use a 2M talkie to
> probe for the weak spots in their system. The most common causes are
> poorly made splices, many (most?) of which are made by customers
> installing their own illegal connections to the system.
>
> 73, Jim K9YC
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