Noticing some WSPR activity on 504 Khz band and having 0 experience of bands
below 1.8Mhz I just tuned-in to see. Just using my untuned vertical and
despite my very noisy location I received the SM6BHZ beacon immediately.
Reminded me when I first heard W5UN on 2m EME (just using 4x9 home-made yagis
made from Al recovered from the bin...)... magic !
Knowing the improvement brought by the RX-loop on 160m, I decided to try
quickly something to see if the 160m loop could be tuned down to 504kHz.
http://f6irf.blogspot.com/2008/05/multi-turns-magnetic-loop-for-top-band...
A quick calculation, indicated that I needed around 1nF capa to get the loop
to resonnate at 504. in fact 1nF was not enough, the final value was found by
experimentation (just using the band-noise to find the resonnant freq) to be
around 1390pF (2x470pF + 2x220pF silver mica caps + a small 40pF adjustable
cap), which means that my 6 turns loop has an inductance of approx 72uH (and
not 100 as first estimated !). At this frequency, the bandwidth is extremely
limited, just approx +/- 1.5kHz at -3dB.
I then discovered, that the IC756pro2, did not have sufficient sensitivity to