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Probably an inv L or T antenna as high as possible
for TX is the best solution for 9 kcs. Base load the antenna with the
necessary inductance for resonance and if necessary add another small
inductor in series to ground and adjust with taps up from ground to get a 1
: 1 match with the coax feed from the TX, readjust the main inductor to
maintain resonance if necessary.
This system has never failed me on 73, 137 and 500
kcs and this would be my approach on 9 kcs.
RX is a different matter and there are a variety of
antennas suitable.
I can RX the Alpha signals around 12 kcs at good
strength using my 500 kcs 1/4 wave inv L and weaker on the 40m loop both
antennas not resonated for 9 kcs.
Obviously if resonated the signals would be very
strong with these antennas.
9 kcs is a lot easier to get going than the other
LF/MF bands because there is an abundance of LF generators and high
power audio amplifiers about,
I would suggest modifying a audio amp output to 50
ohms with a suitable transformer then use existing station equipment for
monitoring and measuring.
Suggested approach for making a large inductor to
resonate antenna.
Get several slotted laundry baskets size diam
600mm, height about the same, stiff plastic material. Wind some wire on a few
and connect in series with antenna and check for resonance, then add baskets as
necessary to resonate at desired frequency These baskets fit into one another
and look tidy.
Use the largest diam wire possible to achieve
the desired inductance. If using a vy small inv L with lots of Henries required
then go for the water butt coil former.
Do not forget some earth radials and
rods.
I could probably manage about 4 inv L antennas in
parallel, 500 kcs size, loaded against ground and would hope the signal
would travel some hundreds of miles.
If only I had the time.
de mal/g3kev
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