Hi Ric,
In my calculations I assumed a perfect (capacitance free) coil.
I found out that my 4.5mH loading coil has a self resonance just above
700kHz, so upward from there the reactance will drop rapidly (and will
become capacitive).
So it is very likely that a LF antenna can radiate very efficient on
particular frequencies above 1MHz.
It might not be a bad idea to have the harmonic radiation checked by
another ham living 10-20km away.
73, Rik ON7YD
At 09:10 11/05/01 +1000, you wrote:
G'day,
Robert, AX2TAR, tried his switch mode LF transmitter without a low pass
filter. His 3rd harmonic was just visible on Argo, but his 19th harmonic
at about 3.3MHz was S9 here about 10km away.
The 19th harmonic was probably where his wire was a halfwave long and
excited via the stray capacitance across his loading coil.
73, Ric, VK7RO
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