Re: Halloween Coiling and the FCC

["Tesla list" <tesla-at-pupman-dot-com>]

Original poster: "Winston Krutsch by way of Terry Fritz <twftesla-at-qwest-dot-net>" <u236-at-earthlink-dot-net>

Hi Dan, All,

	This sounds bad, since I have an airport about 4 miles from my
house...  But, is the LF radiation from the coil of much concern to the
airport?  I think some navigation beacons run at low frequency, but
maybe I'm wrong?

	I think the parasitic oscillations in the tank circuit that run into
the multi-MHz and 100 MHz range are of more concern, since they are in
communications bands (I think).  Has anyone detected these VHF range
signals at any significant distance from a running coil?  I know much of
the VHF hash comes from the sparkgap itself.  The same interference is
caused by electric drills, saws, and other devices with brush-type
motors, and people don't usually don't care about it.  Also, I don't
think that airports have much of a problem with it.

	I'm just wondering if my situation really warrants caution from a
radiated RF standpoint.  I run my coil outside often, and even with a
crummy RF ground, and no line filters, my mother reports only minor TV
interference (when the coil is in tune).  When out of tune, the TV
wasn't watchable :-0.

Thanks,
Winston K.

Tesla list wrote:
> 
> Original poster: "by way of Terry Fritz <twftesla-at-qwest-dot-net>"
<dhmccauley-at-spacecatlighting-dot-com>
> 
> I know a lot of people here claim that tesla coils are quite "lousy" at
> being antennas and all that, but they throw a whole huge amount of RF hash
> out in the atmosphere especially when run outside.  Especially in a very
> urbanized area, you may attract the attention of other "listens" especially
> if near an airport, etc...
> 
> My very good friend Lou, a seasoned ham operator, made a bet with me.  He
> claimed he could hear my tesla coil with his antennas at 20 miles away
> during operation.  Since "the group" here previously claimed that tesla
> coils were lousy radiators, i figured i had that bet won.  Anyways, i set my
> coil up outside and he and my friend were at his house where all his ham
> equipment was set-up.  We then synchronized our watches and he informed me
> to key at random 3 short pulses.  This was accomplished by quickly turning
> off power to my 15kv/60mA NST.  He then told me to do this at random
> intervals for the next half hour and that he would record the exact time he
> received them.
> 
> Well, sure enough he got almost all the transmissions.  He also picked up to
> the 3rd harmonics of the signal as well which were much fainter no less, but
> still detectable.
> 
> We then reversed roles and repeated the experiment.  Voila.  Same results.
> And it was blatantly obvious when that thing was on.
> 
> I never would have thought it could be such an efficient radiator!!!!  I'm
> convinced now!!!!
> 
> HOWEVER, it still wouldn't stop me from firing my coil up outside.  I'm
> going to do the same.  Of course, halloween is the perfect excuse to run the
> coil outside!!!!
> 
> Dan
>