[RFI] Cable interference

Cortland Richmond ka5s at earthlink.net
Thu May 12 04:27:49 EDT 2005


You are on the right track and in the right place. 

Check out  http://www.arrl.org/tis/info/HTML/catvi/catvi-leakage.html 

Note this from that page (excerpt): 
"Contact the local cable system, and ask for the Plant Manager (may also be
called "Chief Engineer," "Chief Tech," "VP of Engineering," or similar).
Let him or her know what's been going on with leakage on Ch. 18. Add that
you'd be appreciative of any cooperation to resolve specific leakage
problems. Also let him or her know that offsetting Ch. 18 might go a long
way toward reducing or eliminating interference on 145.25 MHz, and ask if
it would be possible for to do that. 
As a side note, some cable systems have done this where a 145.25 MHz
repeater was in use. The nice thing is it's a "free" fix that works quite
well. Granted, it won't eliminate leakage (that still has to be kept in
check), but it will substantially reduce the possibility of on-frequency
interference. "

Since they pay folks to find illegal (unshielded) hookups, and tighten 
loose connections, might as well let them do it. They may even be eager to
find leaks, since Comcast (if that's your provider) in Lyon Township got a
violation notice for leakage in February. See

On the Madison Heights Web site I see your cable companies are 
Comcast  at (248) 353-3900 and WideOpenWest at (866) 496-9669  

Meanwhile you can still be tracking down (a small beam is good for this)
where the signal is coming from.   And did you talk to folks at your local
radio club? Where a long standing problem exists, they may just know who to
talk to to get results. 

I've had trouble (or it could be old ears) using an FM rig for tracking
down a carrier because once the signal is strong enough to quiet background
noise, I can't hear if it gets stronger.  You can tune up or down 15 KHz or
so -- just far enough to make it a bit noisy -- and that will help in
hearing changes. (Quieter is stronger.)  Listening to a harmonic may help.
too. Incidentally, while an S meter is a great idea, it takes attention to
watch the readings, and so I'd not recommend the S meter method while
driving. I've had better results using a handheld receiver with SSB, since
I can usually hear signal strength differences in that mode, but not all of
us have one that covers 2 meters.

Let the List know how it's going. too!


> From: Sean  (K8KHZ) <sean at k8khz.com>
> Date: 5/11/2005 7:49:08 PM
> Here locally we have a repeater that is on 145.250  While listening to it
without the tone squelch on there is a s3-s5 noise floor of a carrier that
keeps the radio squelch open. 
> This noise is I think cable noise. 
> Can I use just my radio on that freq to hunt down the source?
> Or is there more too it?

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