#Radio Animation?
25-Jan-95 22:33:23
Sb: #149027-#Radio Animation?
Fm: Don Landis 71673,3612
To: John Ellis 72440,3046
Now for the serious guess:
Do you have a nearby FM station transmitting tower? Say one that operates at
about 90.1 or 89.9 Mhz. These would be the nearest station channels that are
in heterodyne frequency range of the 90 Mhz Pentium freq. you now have. My
guess is that by coincidence you have created a tuned circuit that acts as a
very sensitive antenna for this station and have picked the signal up on your
network cabling. This FM station then beats with the 90 Mhz. local oscillator
in your Pentium and produces a lower frequency that can be radiated via your
modem speaker or MB speaker. Normally this phenomenon occurs with AM stations
but I have run across it with FM stations too because of some residual AM in
the FM signal. People have picked up radio signals in their false teeth and
other peculiar locations.
>> so it might have to do with "cable" which is wired into the system.
You maybe getting warm now. Cable systems often carry FM stations at the same
frequencies so they can be tuned by a normal tuner. Our cable co does carry
about 20 local stations here. But, why would you hard wire your cable TV
signal to your computer? Do you have one of those computer TV cards? TV in a
window? This also may be how your FM signal is getting into your computer.
Based on the disconnect evidence I still support my tuned antenna theory. A
quick way around this would be to insert a T connector in the network thin net.
attach a 1/4 wave of cable to the T. tune it for 90 Mhz. You need to take
into account the velocity factor for the cable you use on your network to tune
it properly as a 1/4 wane is not a 1/4 wave when working with coax. If you
need further help with this I can look up the Vel. factor and calculate the
stub length for you. A 1/4 wave stub is a dead short for a certain frequency.
These are pretty high Q so I would recommend making it a little long and then
snipping off 1/8 inch at a time until the music stops.
Now if you think this all sounds like BS you're probably right, but you can ask
Gus Grubba and he'll tell you this is a legitimate remedy assuming my guess as
to what is causing your mysterious music is on target. If this doesn't work
then I'm at a loss as to what may be causing it until I get more info.