Dear LF Group,
Thanks to ON7YD for the equation for monopole capacitance and
reminding me that the 6pF/m is for thin conductors. Jim's
(M0BMU) comments on relays and thick monopoles were also very
helpful. I hope my maths were OK in calculating the voltages.
It appears that that ~450 pF is a reasonable capacitance and
that suspicions the base insulator has suffered ingress of brine
water are unfounded. Thanks to all.
Last night, the Decca was used briefly to feed a kW (4.5 RF amps)
on 137.777016 kHz to the 100m wire by popular demand (at least F1AFJ
and DK7FC anyway!) CSignal reports from RN3AGC (Moscow) 4X1RF
(who also reported a reception in Bucharest) F1AFJ, PA3CM and
DK7FC are gratefully acknowledged. Signals were seen on the G4WGT,
DF6NM and F1AFJ grabbers.
Experiments will continue with feeding 137.777 kHz to the the
tower in the near future.
The 507.77 kHz transmissions continue. For the benefit of
K2ORS and others who are curious, the power is 80 watts,
1.5 amps to the tower via 200 uH. The 500 kHz TX hissed
loudly when the Decca was keyed so it was switched off temporarily
during the 137 kHz operation last night.
73
Joe
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