[AMRadio] re: mystery interference

[RABRUNER at aol.com]

 Sounds like you are listening to your TV set.  The strong 3.58 MHz signal 
you are hearing is the Color Burst oscillator frequency, and the 15.7 kHz 
spaced frequencies you are hearing are the harmonics of the horizontal sweep 
in the TV.  They would have sidebands at 59.94 Hz, which is the vertical scan 
rate, and yes, they would be very stable as quite often the ultimate source 
of these frequencies is an atomic clock, or at least a high stability 
precision oscillator. Your TV phase locks to the synchronizing signals from 
the TV station with a high degree of precision. You should also be able to 
hear them all over the AM broadcast band.  If the offending TV isn't in your 
house, then it might be a neighbor or two.  A little direction-finding with 
an AM broadcast portable will help you pinpoint the offender.  Getting them 
to buy a new TV, which may or may not be better shielded another matter.

Bob Bruner
WB4TAJ/9


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