[RFI] CATV Leakage? Horizonal Osc Harmonics

[Jim Brown]

On Mon, 11 May 2009 08:05:35 -0700, Michael Tope wrote:

>If the comcast system is leaking, you should be able to pick-up leakage 
>in the VHF band. 

Yes. The picture carrier of an analog TV signal on cable channel 18 is 
145.25 MHz.  

There are three principal mechanisms by which the carriers Larry is 
hearing are radiated. 

1) Directly by the TV set's internal wiring because it is poorly 
shielded.

2) Common mode onto wiring connected to it.

3) Differential mode as a signal on the CATV coax.  

I strongly suggest that you find one of the VHF/UHF talkies that 
includes a receiver for the HF bands and do a bit of poking around your 
neighborhood.  An HF transceiver in your car working as a mobile 
receiver can also be a useful probe. 

Differential signals leaked from CATV systems occur at bad splices. Tune 
a 2M talkie to 145.25 and run around the neighborhood looking for that 
Ch 18 pix carrier.  I found one of my own very old crimped cables was 
leaky. I replaced it with a cable having a much better connector reduced 
the leakage by 10 dB.

73,

Jim K9YC