Re: LF: VX9MRC QRV 507.77 kHz/ Arcing relays &c.

[jcraig@mun.ca]

Dear Group,

I'd like to thank all those who sent their ideas. DK7FC suggested
shunting the LF tuning coil with a series resonant LC, but ON7YD
said it could affect bandwidth on 160m.  Stefan wondered where
the 50 kV was coming from.  That was an upper limit guess based
on modelling a short monopole.  1000 watts at 50 ohms is 4.47 amps.
Feeding this into 3 mH (X=2500 ohm at 137.8 kHz) gives 11.2 kV (17 kV 
peak) so  relays in series as suggested by G8FZK and G3NYK should work
well.   Alan's idea of 'mechanical amplification' had cross my mind too!

I'm puzzled by the 6pf/metre rule for monoploes.  It seems the capacitance
of the monopole is much higher.  Perhaps I've erred again! Please feel 
free to critique my silly calculations above.
The 8 WPM beacon is running on 507.77 kHz now with 80 watts to a vertical
located at GN37.

73 and thanks
Joe


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