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RE: Re: Large ferrite cores for SSTC work

Original poster: "by way of Terry Fritz <twftesla-at-qwest-dot-net>" <rob-at-pythonemproject-dot-com>

I usually think of these circuits in terms of transmitter and antenna.  In
fact I have a very large coil wound out of 1/4" tubing.  It resonates at
1.8Mhz.  If I put an SWR meter between it and my 3kW (Eimac 8877) linear
amplifier, I get the most output when SWR is low.  In this case I feed the
rf in via a tap one or two turns up.  Rob.

ps. this setup runs CW.  If I modulate the RF using AM, I can talk into the
mike, and the big purple flame at the top of coil acts like a speaker :)
Just like in Biblical times

>----- Original Message -----
>From: "Tesla list" <tesla-at-pupman-dot-com>
>To: tesla-at-pupman-dot-com
>Sent: Wed, 15 May 2002 11:47:20
>Original poster: "Jan Wagner by way of Terry Fritz
><twftesla-at-qwest-dot-net>" <jwagner-at-cc.hut.fi>
>> If the transformer core is heating up and you
>have corona, then you have
>> a misdesigned transformer.
>Yeah, that's true, but despite everything I tried,
>it just didn't work out
>to un-misdesign the transformer... :( 
>Maybe I got the formulas wrong, somehow. I've a
>design sheet up at
>calculating the number of turns required. Maybe you
>could have a quick
>glance and check whether or not the numbers seem to
>be in the ballpark? 
>(i.e. for a fullbridge with 5cm^2 e-core 3c85,
>150kHz, 350VDC in, 1400
>Gauss delta-B, 32 pri turns is the real minimum?)
>> It is there simply to match the FET driver to the
>input of the
>> magnifier.  If you have < 2:1 SWR into the
>magnifier, then most of the
>> available power will go to the magnifier and
>sparks produced.
>By "match", you probably mean a current the driver
>can deliver at which
>it does not yet blow up? At this (and smaller)
>output current, the driver
>and coil impedances will always be "matched". I
>don't know about SWR -
>there shouldn't be any, unless the fets once again
>decide to blow up or
>the driver goes to PWM/PW limiting.
>> 1:10 ratio is on the high end.   Rob.
>*ouch*! I did built a couple with >1:20 ratio
>(about 6kVac), although I
>started with 1kV. 10cm was the best streamer length
>subjectively impressing, objectively not. :o(
>many thanks,
> - Jan
> high voltage at http://www.hut.fi/~jwagner/tesla
>.xls which I used for