Re: FSL Antenna

Gary DeBock

On Wed, Dec 22, 2021 at 11:52 AM, John Vinther Nielsen wrote:

I have built an FSL antenna 3.5 Long rod, on the drawing it seems that 23 surplus is needed, I have used 24 must there be  changed on 27 tuns Linz wire or is this OK. and I use a 384 pf capacitor.  

 Another issue is there is too much noise indoors for this type of antenna.


73*s from

John Vinther Nielsen

Herning, Denmark

Hello John,

Congratulations on your FSL antenna construction, and thank you for the photo.

The number of ferrite rods and Litz wire turns necessary for Medium Wave (530-1700 kHz) band coverage in an FSL antenna depend on which type of ferrite rods you are using (the permeability, inductance and diameter) and also which type of Litz wire you are using (the inductance and diameter). Different manufacturers use different materials for construction, so if you want to use an FSL design photo as your guide in building your own FSL, it is only accurate for duplication if you use the exact same type of ferrite rods and Litz wire as the FSL in the design photo. The diameter of the material you use for an inner core also can affect the number of ferrite rods you will need to make a cylindrical shape of ferrite rods.

In my own FSL antennas, for standardized design, I always use Russian surplus ferrite rods or bars (400 permeability), 1162/46 Litz wire from the eBay seller "Mkmak222," and a "384P" variable cap from Mike's Electronic Parts. If you are not using these components, or if you are not using a rubber plumbing coupler of the same diameter as mine for the inner core, then your design will be different than mine, and you may need a different number of ferrite rods, or a different number of Litz wire turns to have the full 530-1700 kHz coverage. Your FSL will probably work very similar to mine, but just have slightly different components. If somebody wants to make an all-new FSL design, my recommendation would be to use whatever ferrite rods and support material you have on hand, and then wind a Litz wire coil that will give you full 530-1700 kHz coverage, regardless of the type of Litz wire. Experimentation can be a lot of fun, so be creative, and your FSL will probably be very effective in tracking down the DX, John!

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

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