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Re: Tesla Receiver Coil ..........success?



Original poster: Ed Phillips <evp@xxxxxxxxxxx>

"Thanks for the detailed description of your beacon, that's exactly what I was looking for. I'm planning to build a Part 15 compliant beacon myself and am wondering if you could share the circuit diagram and parts layout. In addition to a Part 15 radio beacon I also plan to build a Part 15 compliant Tesla coil transmitter that uses a nearly identical driver circuit. Both transmitters will be designed to operate on the precisely the same frequency, around 165 kHz. The radio antenna is to be a 49-foot tall vertical (including tophat radius) with an 8-foot high counterpoise, as large in diameter as possible (on the order of 150 feet). The loading coil is to have an aspect ratio of about 1:1 and be wound with AWG 22. A variometer will be used for tuning. AWG 22 will also be used for the TC transmitter secondary."

I like that counterpoise! Where can you find the space for it? I'll try to dig out the schematic. If that fails I'll trace the circuit by hand but I'm pretty lazy so that will take a while.

The transmitter is solid state . . . Uses a crystal oscillator at 32 x the output frequency, a CD4024 divide by 32 circuit, a CD4007 buffer amplifier driving four Siliconix VN66AF "power" fets.

"Am I correct in understanding that the four VN66AFs are connected in parallel?"


Yes they are [with ferrite beads on drain and gate to suppress VJF oscillations) but there are a lot better FET's to use now; remember this was over 25 years ago.

"Not sure if I answered all of your questions, and probably none to your satisfaction. . . .On the contrary, your insights are tremendous."


I just dug out of my files all but the first two pages of a 22 page set of notes I put together when we were putting out those kits and trying to get guys on the air; includes schematics and suggested coil winding details. Too much stuff to scan but I could probably copy it for you sometime and send the package to you. Give me your mailing address and I'll try to work up the ambition. All I have to do is remember how to make two-sided copies as I'm too cheap to pay postage on 20 pages when 10 can hold all the dope. By the way, this was so long ago that you could get new crystals in FT-243 holders from Jan Crystals for only $1.50 each!

Ed