[RFI] CATV Upstream Interference

Roger (K8RI) k8ri at rogerhalstead.com
Thu Aug 27 09:42:18 PDT 2009

Jim Brown wrote:
> On Thu, 27 Aug 2009 04:15:10 -0700 (PDT), Luciano Nachif wrote:
>> Am I right when I say those few places where I hear the 29.207 
>> signals are the strongest ones so they actually are the leaking 
>> spots?
> Yes. And the most likely cause is a bad connection of the coaxial 
> cable shield. These connectors are crimped onto the cable, and 
> it's easy to have a bad connection if the worker is careless, or 
> if the wrong crimp tool is used, or if the crimp connector does 
> not match the cable (each cable type requires a slightly different 
> connector based on small differences in cable diameters and shield 
> type). 
> BUT -- another common cause of leakage is an illegal connection 
> made in homes by someone who doesn't want to pay the cable 
> company. 
The most common one is where people have an outside antenna connected 
directly to the set input along with the cable *without* and A/B 
switch.  If there are outside antennas in the are this would be another 
check .


Roger (K8RI)
> Another tip for locating the leakage points -- take a VHF talkie 
> and look for the trash next to the cable. Before you start 
> walking, listen to the cable on the talkie and tune in some 
> signals that you know are coming from the cable. Then put the 
> cable back together and listen for that signal next to a cable 
> splice that you suspect may be bad. 
> In general, the higher in frequency that you are able to chase a 
> broadband radiated source, the closer you will be able to "home 
> in" on it. 
> There are a few guys on email lists that I read (maybe this one) 
> who have recent experience with CATV, and may have more advice for 
> you.
> 73,
> Jim Brown K9YC
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