Hi Alan and group,
thanks for the fb report and pics about my tests and QSO with OH1BS on 137.0kHz
yesterday night.
Though I normaly really dislike the cold weather (as does my 17-year-old Golf
Diesel which is supposed to take me to work), the one good thing about frost is
the improving LF-antenna performance. Series loss resistance goes down by 1 to
2dB, and surprisingly, in addition to that I seem to get another 1dB from
increased effective antenna height, as measured by comparing received voltage
against a non-resonant loop. There are a few high fir trees in the vicinity of
the aerial, and I assume that under heavy frost, the shunt conductance of the
trunks falls below the capacity of the tree crowns, so that electrostatic
shielding is significantly reduced.
In yesterday's tests, I got up to 2.7A into the 220pF top load from 160W, but
visible corona appeared at the ends of the thin wires (two parallel lines of
0.5mm enameled copper having U-shaped end connections). After adding extra
short pieces of crosswire at the end of the leg that was most affected, I can
now safely run 2.5A (about 13kVeff).
Still amazed that Peter manages to get up more than 4A at 73kHz ;-)
73 es all the best
Markus
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