I remember when my neighbors connected the cable television to their
rabbit ears antenna so they could "broadcast" to the set in the bedroom
and avoid the charge for having a second set.  Of course this also
allowed my low band transmissions to get into the cable and wipe out
other receiver front ends.  

A friend ran high power on 2 meter SSB and the mayor of the town called
in the FCC.  The government investigator found the ham station was legal
and clean.  The mayor had extra sets hooked up with twin lead and the
cable company got a citation for many leaking connections.  
I suppose the cable companies still transmit that warbling signal around
108 MHz so the repair guys can hear it on the FM band while driving
around town.

I think signals on a cable television system run from about 30 MHz to
close to 1,000 MHz.


Mark