On Feb 13, 8:59*am, dave wrote:
On 02/12/2011 09:02 PM, wrote:

On Feb 12, 1:46 pm, *wrote:
On 02/12/2011 06:31 AM, m II wrote:

This is an accumulation of seven years worth of work on this pest.
Nobody disagrees with me.
NTSC redefined it slightly off 60Hz so that power supply ripple
will move on the screen (two slightly black bands that scroll
up/down your screen

That's usually another TV signal. The speed at which the black bar moves
is the difference between the two stations' oscillators. All obsolete now.

Total DISINFORMATION !!!

I'd see it all the time in the San Gabriel Mountains. When I was
transmitter supervisor at channel 30, KCET (channel 28) would get into
my Tektronix demod. Cable TV guys still have to mess with it.

We must be thinking of two different problems having same the
symptoms . Did ch.28 interfere with ch. 30 ; how close to each other
they used to be ? This is extremely rare,in my experience,btw . KCET
must been having a problem for a while that is not addressed or nearly
impossible to solve do to it's proximity to other operators !