Well - let us say - the antenna tunes down to 500 kHz, but the output looks lower than I get from the ferrite antenna of the ATS-909. The S/N, however sounds like it is better.
The source of the lower output ? I am not sure, but suspect the small size of the loop contributes, and perhaps the coupling winding is not enough with a single turn. further tests are needed.
OK - this antenna is rather small and uses standard hookup wire, so the highest efficiency is not to be expected. a somewhat larger antenna, say 1x1 m made from Litz wire should provide substantially better results.
The first test was with a "dual gang" variable capacitor, but with only one plate set used. of course the hand capacity detunes the antenna so it is essentially untuneable.
SO the second test was with both plate sets, and now we are getting there. because the hand is at the center of the capacitor, no detuning or hand capacity effect is noticeable.
With the 25 windings, the antenna tunes down to just under 500 kHz, so the antenna is a qualified success.
The ATS 909 seems to have a rather good sensitivity on MW, so it is a bit difficult to fully judge the efficiency and usability of the antenna.
The tuning is not *very* sharp, but with a decent maximum at resonance.
The next test should be connecting the antenna to the HF-3 RX which should have a very high sensitivity on 500 kHz. Oh, now for soldering another connector to the cable and see what it will do.
Another solution to the low output could be to build an amplifier, but that sort of defeats the purpose of a 'simple antenna'.
More room for experimentation.
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