Re: New antenna, new loggings


OK, now I am getting somewhere, at least in my mind. A 30 inch diameter, with 1/2 inch spacing [I think I need that to prevent capacitance between windings?] gets me to 258 uH with 15 turns and the wire I chose.
Now I need to think of a coil form that big. Sonotube? Made up from long strips of Masonite? If I can't come up with a round form, would you happen to know how to calculate for a square one?


--- In ultralightdx@..., "jim_kr1s" <jkearman@...> wrote:

--- In ultralightdx@..., "farmerik" <farmerik@> wrote:

Thanks for the additional explanation, it is clearer to me now.
What sort of loop would I wind if I wanted to connect it directly, and
not use a torrid [or other] transformer?

In that case, the inductance of the antenna has to resonate directly
with the varactor diode on the chip. Taking into account stray
capacitance in the connecting wires and the loop itself, design for
about 240 uH. This calculator should get you close.
<> It
gives more accurate results for large air-loop coils than the one called
"Professor Coyle."


Jim, KR1S <>

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