Re: blanking police radio

["Tesla list" <tesla@xxxxxxxxxx>]

Original poster: Ed Phillips <evp@xxxxxxxxxxx>


Hello everybody,
   I did an experiment once to see just what kind of interferance 
TCs can cause to radios.  I set up a very small spark gap tesla coil, 
and had a radio (for listening to music or whatever).  The radio was 
2 feet away from the coil (which did little else other than make 
corona, as the secondary was 1.5in by 7in).  What I found was that it 
always generated a little bit of interferance in all ranges (AM and 
FM) but only in the low AM range was any clear definant noise heard 
(a very loud and suprisingly stable hummmm) once the radio was tuned 
to the mid and upper AM ranges, the hum turned to an intermitted 
quiet crackle, which persisted into the upper FM ranges.  So I would 
say unless the Police radio was in the low AM ranges (which it 
clearly isn't), there is no way a tesla coil could cause a 
substancial interferance of any kind.  But I am no expert, just felt 
like putting in my 2 cents!
Scott Bogard"

   You are pretty close there.  The interference to the VHF/UHF 
police radios will be from ringing of the leads in the spark gap 
circuit rather than from resonances in the TC itself and they will 
have significant level in the VHF region.  In spite of that any 
interference would be limited to at most a block or two and wouldn't 
be "blanking" but just annoying buzzing.

Ed