Doc,
I understand the issue raised by Dick (his comments below), but those
comments apply to the radiated spectrum from the TV transmitters
themselves and the effects upon the local areas in which those
transmitters operate. The issue you raise has to do with the noise in the
local spectrum at and around your QTH as a result of a cable-based system.
That issue is more controlled by the following factors:
- Quality of the cable and the connectors used (ie, RF "leakage")
- Quality and design of the interface boxes (how much do the interface
boxes for Bright House leak, in what part of the spectrum do they leak,
and are they susceptible to nearby transmitters?)
- Quality and design of the box that goes inside the house at your TV
(same issues as above)
Depending upon your main frequency bands of concern (HF, 6m, 2m,
whatever), I would take a portable or mobile receiver that covers the
bands in which you are interested and visit a neighborhood in which this
system is active. Listen for increases in the noise spectrum as heard on
the receiver or for interference to stations that you have tuned in. Of
course, that is not as definitive as evlauating it in your house, but it
might give you enough input to make a tentative decision. If you decide
to get the service, be sure that you can get a refund if it interferes or
if the system gets clobbered by your transmitters.
As you walk or cruise around, try to place your portable or mobile radio
at a distance similar to that which would apply at your QTH. Remember,
it's not where the radio will be, it's where your antennas wiill be that
matter.
73, Dale
WA9ENA
kd4e <doc@kd4e.com>
Sent by: rfi-bounces@contesting.com
04/19/2008 04:35 PM
Please respond to
doc@kd4e.com
To
RFI List <rfi@contesting.com>, "tvi-rfi-emi@mailman.qth.net"
<tvi-rfi-emi@mailman.qth.net>
cc
w7tio@juno.com
Subject
[RFI] TV Converter Boxes & RFI
Since they just ran a Bright House cable next door in our
*very* rural neighbohood (10 acre lots) to a pole that is
about 120 feet from the house should we anticipate a rise
in RFI?
If I we to allow them to run the cable to our house would
that increase RFI?
> First a comment.. This subject DOES impact ham radio, for in a larger
> city with multiple Digital TV stations, which are normally "megawatt"
> stations, the noise floor for VHF repeater inputs rises accordingly,
> for digital pulses are full of spectrum noise!
>
> In Portland, Oregon with channels 2, 6, 8, 10, and 12, and not all
> converted yet, it rose 20db! This translates out to a factor of some
> 120 times the origional noise!!
>
> Dick, CET (I'm licensed TV tech!!)
--
Thanks! & 73, doc, KD4E
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