Graham Phillips wrote:
Hi Geri, Dave and all LF'ers.
I am following with great interest the debate on our relative signals.
G3YXM / G3XTZ )
As Dave said, my vertical is 20 meters high, but the two 10 meter loading
wires from the top have to slope down at about 45 degrees ( to fit in the
available space ). I have always thought that the effective loss of height
was a price worth paying to avoid the need for a much higher value of
loading inductance ( and loss ) at the base of the vertical. However, I am
now FORCED into the position of HAVING to find a few more dBs of signal !!!!
I would like to hear what others may think of the options: (1) eliminate
the top capacity loading, and wind a bigger loading coil. ( 2 ) Fit a
small, lightweight inductance at the top of the vertical and reduce the
length of the capacity wires. ( 3 ) A combination of both. ( 4 ) Move.
I would prefer the fourth option, since the local QRM here is curtailing
activity severely, but it is also the most difficult !
This seems a situation that would benefit from a separate RECEIVE ONLY
antenna. The bigger and better the LF transmitting antenna, the wider
the near field becomes from the point of view of local QRM becoming a
nuisance. Several ZL LF experimenters, including myself, use separate
antennas for receive only. An active whip, with JFET source follower,
sited "down the backyard" can give a welcome improvement in S/N compared
to receiving off the "big wire". There are even better types of
specialised receive only antennas, but they all rely on being located in
genuinely "quiet" spots for QRM.
Regards,
Bob ZL2CA
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