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From: slipson@bbnccv.UUCP (Sam Lipson)
Newsgroups: net.video
Subject: AC on Cable?
Message-ID: <35@bbnccv.UUCP>
Date: Sun, 24-Feb-85 20:13:21 EST
Article-I.D.: bbnccv.35
Posted: Sun Feb 24 20:13:21 1985
Date-Received: Thu, 28-Feb-85 01:13:25 EST
Distribution: net
Organization: Bolt Beranek and Newman, Cambridge, MA
Lines: 34


	One of the folks here has cable at home,  and has an
interesting problem.  Whenever he hooks his stereo up to the 
cable he gets an AC hum through the speakers [note he doesn't
need to turn the stereo on to hear the hum].

	{The intent was to be able to tune the MTV FM stereo
portion.}

	A test light shows that there is a significant AC potential
across his cable (perhaps about 110VAC).

	Has anyone heard of this before?  Is this a way for the
cable company to keep people from making their own unauthorized
connections?

	The cable company's box does not derive its power from the
cable (i.e. is has an AC power cord like most).

	Presumably to safely attach his stereo he would want to
isolate the FM signal from the AC.  Any ideas on how to do this?
(Commercially available preferably)

	I'm not so sure I'd want to connect this known live cable to 
my television directly either,  presumably the cable converter box 
idoes a good job at isolation.

	I guess one could always consider free power another advantage
of cable. (Then when the lights go out you could blame have two different
"utilities" to blame)


A
A