[Lowfer] LITZ wire X enameled

[PY3CRX PY2PLL]

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