Re: Gary's New 6" FSL Design


Thanks Gary for the detailed response.

When endeavoring to obtain the highest resonant signal output at a given frequency, the Q needs to be high as practicable. The audio fidelity will be somewhat compromised, but this can be partially improved by slightly tuning the FSL antenna to peak 1 or 2 KHz above the carrier frequency. This is why the 8:1 reduction drive is essential. 

High Q FSL antennas are the only way to obtain similar RF gain and selectivity in a small package that favorably compares to large 4 - 6 foot air core box loops. This means a 6 inch FSL can be positioned pretty much anywhere within the house. A 6 ft air core box loop positioned on the kitchen bench top is not practical. But a 6" FSL would easily sit there.

The 6" FSL with 1162/46 Litz wire will likely be more expensive for DXers outside the USA and China. I estimate the total cost for me would be around AU $250 including parts postage.

For those DXers that seek weak signals only 9 or 10 KHz adjacent to very strong locals, the high Q FSL is ideal from a 3 dB bandwidth perspective. The disadvantage is no tilting provision for reducing local signals by > 60 dB. This Kiwa loop tilting mechanism was very good for obtaining the critical tilt angle for nulling a local signal.

One possibility is to video a 6" FSL comparison test against the large 9 foot air core loop. If the results are comparable, that will be an amazing achievement in itself. Interesting to see what your most distant daytime MW groundwave signal that can be obtained with both antennas.



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