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
_______________________________________________
RFI mailing list
RFI@contesting.com
http://lists.contesting.com/mailman/listinfo/rfi
|