Re: New FSL

Steve Ratzlaff

Hi Dean,

Gary will have his own comments, and he's done a lot more with FSLs in the past couple years than I have.

Litz wire, if large enough, is always superior to non-Litz for a FSL (and for most any type of small loop antenna not exposed to the elements--as Litz will readily rust if  it's unprotected and gets wet and then becomes totally useless). Use the largest Litz your budget will allow. I'd suggest 175/46 as perhaps the minimum; 330/46 is good; 660/46 is great. Gary uses the latest monster high-count Litz (very expensive) which I haven't tried yet, which would be perhaps the ultimate. Litz also has less turn to turn capacitance and can be wound with no turn spacing; you normally need to space non-Litz turns one wire diameter apart (or more) to reduce the capacitance.

Ferrite permeability directly affects how many turns you need for a given inductance to resonate with your tuning cap. Most of the Russian ferrite has been a fairly high 400 permeability but lately some lower permeability ferrite seems to be available. Standard permeability of ferrite rods used in portable radios is generally around 150. Using lower permeability allows winding more turns to get the desired inductance--this is an advantage as loop sensitivity is directly related to number of turns. So your use of a mix of 100 and 150 permeability ferrite allowed you to use more turns for your coil than if you had used 400 permeability ferrite--that's good.



On 2/15/2017 6:32 PM, dean_0_way@... [ultralightdx] wrote:

I spent weeks looking for info on what permeability might be best ,i never did get that figured out but i have some 400 perm flat bars  that i may use for the next loop.

I do have a question,
Have you noticed any advantage to using litz wire compared to regular stranded ?
and what are your thoughts on permeability?

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