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Re: Halloween Coiling and the FCC



Original poster: "Terry Fritz" <twftesla-at-qwest-dot-net>

Hi Dave,

At 10:02 PM 10/2/2002 -0400, you wrote:
>
>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...

Yep!  There was a thread about "stealthy" Tesla coils that coil run without
attracting attention awhile back.

>
>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!!!!

Wow!  Neat test!  What kind of signal did you hear?  The fundamental
frequency, spark gap noise???  I imagine it was an excellent radio and all
that with a big receiving antenna.  A Tesla coil my push around about 10
Megawatts of peak power so I am not sure I would call it "efficient" but 20
miles is pretty good since most of us can't get a block or so.

Is it possible the RF is getting back on to the AC wiring where the
"antenna" would be very long?  If you get much power on long AC wires, that
could really help the transmission (not that we want to ;-))  Of course,
spark gap transmitters look like Tesla coils with a really long antenna and
they transmit very long distances.

You might want to check AC line filters and all that and be sure the ground
is good.  Either may cause the coil to transmit dramatically more RF power.
 There are other tricks too depending on what type of signal is being
received and how serious of a problem it is.

Cheers,

	Terry

>
>
>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
>
>
>
>
>> Hi All,
>>
>> This Halloween, I'd like to mount my 2kVA coil on the roof above my
>> front porch.  I plan to use a counterpoise of chicken wire, which would
>> be connected to a "real" RF ground.  I plan also to extend the
>> counterpoise out a little way from the roof, over the walkway, to catch
>> any errant streamers that might come close to people.
>>
>> I'd like some input from people who have "been there, done that", since
>> I obviously don't want to do something dangerous/stupid.  The PSU would
>> be on the roof as well, totally out of reach.
>>
>> Also, I live in the Los Angeles area, which as many of you know is a
>> "paranoid" city, obsessed with anything that has the capacity to do any
>> harm to anything (except cars ;-)).  I don't want the police at my
>> house.  Can anyone advise me here??
>>
>> Thanks,
>> Winston K.
>>
>> PS-I normally do an elaborate Halloween display, and am looking to "kick
>> it up a notch".  It's quite electrically intensive, since I have
>> control/power wire running to various motorized/lighted equipment.  This
>> would be the first year that high voltage would enter the picture.
>>
>>
>>
>>
>>
>>
>>
>
>