Hi Andy
I use Wellbrook loops - 1530 for hf (150 kHz - 30 MHz) and 1010 (10 kHz - 10
MHz) for lf. They work very well with my SDR-14 and SDR-IQ.
The loop feed box is filled with a potting compound to provide weather
protection so you can't see the configuration and no info is supplied with
them. Unfortunately I made the silly mistake of using a transmitting antenna
too close to them - Wellbrook do not repair them but send a replacement loop
unit.
On request Wellbrook replaced my 1010 loop with an lf-enhanced version to
improve response below 10kHz I think by using a coupling transformer giving
a better lf response but degraded hf response. It seems to work well as I
can see the Russian Tx at 11.905 kHz and also get good results at 136 kHz.
I'm building a Miniwhip, so will get the opportunity to compare soon. I can
confirm the benefits of noise reduction. Mine are mounted one above the
other at 20 feet on a fibreglass pole with rotator (I am building your
rotator controller for more accurate control as the null is quite sharp).
I am looking for a suitable circuit to use with the blown loops (they are
not completely dead but have a serious loss of sensitivity but disassembly
is certain to destroy the loop amplifier). I suspect it's not so easy to
form a 1 metre loop with aluminium tubing so the loops can be re-used for
experiments.
I was thinking something along these lines:
http://www.pm.keirle.com/3_radio/hf_loop_ant/hf_loop_ant.htm
http://www.ik4hdq.net/doc/testi/smlloop.pdf
http://www.vlf.it/looptheo7/looptheo7.htm
http://www.vlf.it/lowfloop/lowfloop.htm
However, I look forward to seeing one of your designs Andy!!
If you need more info on the Wellbrooks please email direct.
73 Terry GW0EZY
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