[RFI] The Cable TV issue

Dale svetanoff at earthlink.net
Mon Sep 2 14:16:04 EDT 2013


AS has been mentioned many times on this reflector, the most effective way track down a source is: 1) Make certain it is not in or on your own property; 2) use DF techniques to locate its location if not on your property.

Another ham here in Iowa had an RFI source that was periodic in nature, much like yours.  I suggested to him, and now to you, that you power the radio receiving the interference by battery, then turn of ALL power in your house.  If the noise goes away, it's source is with you.  If it remains, then the source is external and you will need to go hunt down its location.      

The local ham was lucky - killing power in his house caused the noise to go away.  He then restored power one circuit breaker at a time.  Success! The problem was a battery charger that was trying to charge a defective battery pack.  May you be as lucky.  BTW: When killing house power, kill the MAIN breaker if you can.  As others have noted, door bell transformers can sometimes be the problem and they are often (as in my house) located right at the power panel or hidden from sight.  You MUST know for certain that the problem is in your house.  

There have been lots of postings here as to how to track down external RFI sources.  Yours does not sound as if it is power line noise, so it will be easiest if it is something at your house.

You mention that your hand held can't hear the RFI.  I presume that is because it tunes VHF and/or UHF FM only.  Be aware that some HTs have full HF AM reception, the Icom IC-91A and 92A among them.  (Yes, I can listen to WWV at 5 and 10 MHz with my HT as a time check.)  Such an HT would be very helpful in tracking down an external source. 

73, Dale

-----Original Message-----
>From: Charlie Gallo <Charlie at TheGallos.com>
>Sent: Sep 2, 2013 10:44 AM
>To: rfi at contesting.com
>Subject: [RFI] The Cable TV issue
>So, the tech came out today
>The voltage is gone (not the issue), and a loose ground block acting as a diode got rid of about 1/2 the signal, but then we were able to hear what was actually putting the initial RF buzz on the line
>My Motorola SURFboard SB6121 Cable Modem
>Just to let you know, this thing was putting out quite a bit of RF on the cable TV drop
>Now on to the next problem - On 80, there is a once ever 2 seconds (plus or minus, just counting Mississippi)  pules of noise - Bip, Bip, Bip.  2 S units at my antenna.  Problem of course is that the hand held can't hear it
>73 de KG2V - Charles Gallo
>Quality Custom Machine-shop work for the radio amateur (sm)
>RFI mailing list
>RFI at contesting.com

More information about the RFI mailing list