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Re: Colorado coiler teslathon( RF coils )

Hi Al,
        There are problems end-feeding a resonator if its output end
is open circuit because it looks like a short at the base. The feed Z 
shouldn't change a great deal with corona but a struck arc is going 
to raise the feedpoint well above Zo. It's a nasty one for a rig that 
likes working into 50 Ohms. A coupled 2-coil system would perhaps be 
a better option because you can reduce the effect considerably by
making k small enough to give you a feed Z of 50 Ohms. The smaller k 
is, the less Z feed will vary also. But you still have the 50 Ohm 
matching requirement under varying load conditions.
     The inband match I was suggesting would have required being 
offtune for the resonator which isn't terribly helpful I suppose, 
and then of course it's going to vary as a discharge appears.

Malcolm

You wrote:
> Interesting you should ask .. a few years ago I tried building
> what you would call a bi-polar coil that I planed to run at 4mhz.
> the output of the coil went to an ozone generating cell, my idea
> was to see if raising the frequency of an ozone generator to the RF
> range wouls increase the efficiency of the unit ( electric ozone
> generators usually run around 8-10% efficient). The output of my
> Kenwood TS-530s was feed into a Dentron Jr antenna tuner to get a
> balanced output for the TC primary ... to make a long story short,
> the end result was that I was never able to get the tuner to handle
> the impedance of the TC primary ...when I tuned it to resonance,
> the tuner would start arcing inside.. I should have set up the
> primary to a better match .. but It was one of those projects that
> never got completed ... I think if you set up a TC to operate at RF
> frequencies you will get a corona rather than long sparks .. much
> different effects .. you also need to worry about QRM effects
> ..even a good Faraday cage will leak and if it leaked too much, the
> FCC my ask what you are doing!! ..but it is an area of coiling that
> needs to be looked at .. I don't know of anyone who has done much
> work with coils at RF frequencies ....... Al Syme (KG0QJ)
>