Re: Discovery of FSL Antenna Phasing for Front to Side Rejection


Gary DeBock
 

Thanks Michael, Sudipta, Craig, aa, Jay, Max and Paul,

Your comments are all very much appreciated!

This dual FSL nulling procedure has been tested over and over with many pest stations, and works very well once you get the hang of it, and follow the instructions. I have some recommendations for the best results (please refer to the attached photo).

1)  The stronger the pest station, the more razor-sharp will be the null, both with the radio loopstick and with the "Nulling FSL's" variable cap setting. Best results will be obtained by placing the radio down in the exact null position (however "hair trigger" that might be).
2)  You can still null out a pest when DXing conditions are poor, but you may not receive any weak DX station in the null position. On the other hand, when conditions are good, you may end up with two or more DX stations fighting it out with the pest in its null position.
3)  Make sure that you have the exact same inductive coupling distance between the radio and the two FSL antennas (although the two FSL's will be perpendicular to each other, as shown in the attached photo). If you are familiar with using an FSL antenna, you should have some practice determining the best inductive coupling distance on different frequencies (such as around 2 inches for 1700 kHz, around 4 inches for 1000 kHz, etc.). Or, you can simply listen for the best gain boost when you move the "Reception FSL" up to the radio-- that will be the best inductive coupling distance.
4)  So far these experiments have concentrated on receiving DX stations on the same frequency as a pest station. Although this procedure should be effective in nulling out domestic stations on frequencies like 540, 630, 720, 810 (etc.) when chasing transoceanic DX, further experimentation will be conducted for nulling out domestic splatter on slightly different frequencies than a transoceanic target station. If those experiments prove successful, the compact FSL antenna will become far more effective for transoceanic DXing on flat ocean beaches, where domestic splatter runs wild (unlike at ocean cliffs).

73, Gary DeBock (in Puyallup, WA, USA)  
   

Join main@UltralightDX.groups.io to automatically receive all group messages.