Re: FSL Antenna Tuning Course Video


Gary DeBock
 

Thanks Gary. The FSL is very easy to master on radios like the 2010, 803A, 880 etc and similar. The later DSP chip radios like the Skywave etc requires some skill to hear the "peak" as they are quite slow to react to the increase in signal level and can be quite frustrating to those who are used to the older style radios.

Thanks Chris (and Todd),

Todd, prior to our joint Kauai (Hawaii) DXpedition in November I provided Chris with the latest 5 inch "Frequent Flyer" FSL model, but he found it a little tricky to find the gain peaks because of the delayed response of the CC Skywave's DSP chip, which always tries to compensate for any antenna frequency changes. Broadband receivers like the PL-880 and ICF-2010 do not have this quirk, and are much easier to use with a razor-sharp tuning FSL. Despite this a DXer can become pretty skillful at using a CC Skywave with a 5" Frequent Flyer FSL if he practices continuously, and masters the DSP chip quirks.

<<<   Based on all the factors involved, I suggest that building an FSL antenna is much more challenging than operating the finished product.   >>>

Any DXer's first attempt at constructing an FSL will probably be challenging, but once you get used to the quirks they are very simple and straightforward.

<<<   The critical FSL tuning is largely overcome by using a 8:1 reduction drive 384p variable capacitor. The tuning sharpness in the video is similar to my 40 inch PVC box loop. Of course the tuning is even sharper down near the bottom of the MW band, e.g. 531 KHz. But I have never had issues re quickly finding the loop resonant signal peak.   >>>

Actually the tuning sharpness of the latest FSL's (tweaked for the maximum gain) is quite a bit trickier than that of an air core loop, Todd, but with some practice a DXer can adjust to it. On an FSL the sharpest tuning is on the high band, and the low band frequencies (530-600 kHz) tune more broadly (i.e., easier to peak the gain boost).

<<<   I gather your backyard 9 foot air core PVC loop is the benchmark antenna for comparing all your other antennas. Is it possible for say a 7 inch FSL to match the 9 foot PVC loop? The benchmark is daytime stable groundwave. But with all the recent metro stay-at-home resultant consumer electrical noise, the bigger 9 foot loop may only produce more signal and noise. Hence the law of diminishing returns kicks in.   >>>

The signal boost from the 9' air core loop is pretty impressive, but the Monster FSL's (15 inch and larger) can match it in S/N ratio. FSL antennas have a natural tendency toward lower noise reception, so a compact FSL design can usually compete with a much larger air core box loop. The latest model 5 inch "Frequent Flyer" FSL's can usually outperform my 4 foot air core box loop in S/N ratio, primarily because of lower noise reception on the weakest signals. Even the latest "Baby FSL's" can sometimes compete with the 4' air core loop in weak signal reception, especially on the extreme low band frequencies when domestic splatter is an issue.

73, Gary

  

 



 

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