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Old June 2nd 07, 01:40 AM posted to rec.radio.amateur.homebrew
Uncle Peter Uncle Peter is offline
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First recorded activity by RadioBanter: Jul 2006
Posts: 189
Default Question for the group...


"Dave" wrote in message
...
Has anyone ever heard of anything like the experiment I am currently
concocting? I have taken an Amidon T50-2 toroid form and wrapped it with
57 turns of #32 enamaled wire, giving it an inductance of 16 uH, then
wrapped over that layer with 150 turns of #36 wire. The first layer (16
uH) I am using for tuning my home-built active antenna, and am relying on
resonance to send a signal through the outer layer, which I *think* should
act like a step-up transformer for that signal. This layer is grounded on
one end, and feeds into the first stage of amplification on the other.
And it does seem to work, only the toroid seems to resonate at around 10
MHz with my tuning capacitor set to 114 pF, when it should (I thought)
resonate at something lower, like around 3.7 MHz.

And like I said, the step-up transformer part does seem to work, but I
can't tune as low as I would like. Has anyone ever hear of anyone else
trying anything like this? If so, what is it called, and where can I find
info on the subject?

Many thanks for any help...

Dave


What are you trying to match? I suspect your secondary winding has
a lot of interwinding capacity that might be affecting it's operation.
For a ""step up", it might be easier, and more efficient, just to design
a pi or L matching network to do the transformation... Or, use
tapped windings on the coil used in the tuned circuit. Low impedance
at a lower tap point, impedance and voltage will increase on higher
taps..

Pete