[Lf] [Fwd: LF: LITZ wire X enameled]

[Andre Kesteloot]

PY3CRX PY2PLL wrote:

> Hi all ...
>
> I´ve been experimenting with an old design ... a ferrite rod antenna. I have
> a 42cm long X 10mm diameter rod, scrapped from BC radios (2 pieces of 11cm
> and one piece of 20cm glued).
>
> Initially I has about 18cm at the 20cm rod covered by a 0.5mm enameled wire.
> This seems aprox 360 turns. A NTE618 variacap diode tune this setup from
> 120KHz to 500KHz (0 to 13V) aprox.
>
> A sample signal was 9dBuV (330KHz NDB). I added the remaining 11cm rods, one
> each side of the initial one. The tunning range changed and when compensated
> the same signal increase to 22dBuv. Good.
>
> Now a question: should I expect to have more efficiency if I change the
> enameled wire by a much thinner litz wire ? I got some here, seems to have
> 10 strands but the overall diameter is 0.25mm, includying the cotton cover.
>
> The same NDB at a 30 meter high vertical element with 2 X 20m top loading
> (it´s an 80m band inverted vee dipole with inner + braid tied toghether at
> the tower base) has the same voltage reading at 50 ohm (21dBuV)
>
> Aditional comments: I still using a MPF102 pre-amp. The gate is conected to
> one side of the coil which is center tapped to ground. It´s supply is
> provided by a 78L08. All circuit is powered by a 12 to 26V variable power
> supply at the shack via 50 ohm cable. There´s at the antenna circuit a LM158
> voltage inverter/comparator that "converts" 12V to zero and 26V to 13V to
> the varicap control voltage. I use to run a 12V zenner as a voltage drop
> component but hard to solve the generated noise so the op-amp was used
> instead. This circuit is avialable if requested.
>
> Thanks for any comment.
>
> 73
> Marcus, PY3CRX/PY2PLL
> GG66rf
> http://py.qsl.br
> Active from "DC" to 24GHz