Re: Tesla Coil RF Transmitter (long)

["Tesla list" <tesla@xxxxxxxxxx>]

Original poster: Ed Phillips <evp@xxxxxxxxxxx>

"Sorry :-/ I am in the UK. I didn't realise you never
had in the US. Europe has had it since 1998 I think.
There is a restriction of a few watts, but it's ERP.

Ralph Hartwell runs WC2XSR/13 with a 400 watt
transmitter on 168kHz. I think he is still within the
power limit due to the antenna being so inefficient."

	In the U.S. unlicensed transmittion in the band from 160 kHz to 190 kHz
is legal, provided the maximum power input to the FINAL AMPLIFIER STAGE
is less than one watt and the maximum antenna length/height is 50 feet.
A number of people have gotten experimental licenses under Part 5 of the
FCC regulations (forget the CFR #) to operate in this band with large
antennas and much more input power and also more ERP.  Ralph is one.
Several other stations have gotten experimental licenses to operate with
similar powers in the band around 137 kHz.  I don't remember exactly
what the requirements are in Canada but there are stations on the air
across the country.

	There are also a number of legal but unlicensed stations operating in
the vicinity of 13.555 MHz where the power is limited by a specification
of maximum radiated field strength.  This limitation is about equivalent
to allow a maximum of 5 mW input to a half-wave dipole.

	I'm sure that with the help of some creative statements on the
experimental license application some eager beaver could get a license
to operate a CW (or narrow band modulated) Tesla coil in one of these
bands.  In the "good old days" the term Tesla transformer was often
applied to the RF transformer operated in a tuned primary tuned
secondary type transmitter configuration (secondary tuning capacitance
was usually just that of the antenna) and was not confined to the very
high impedance secondaries being used to generate impressive streamers.

Ed