Re: Reliable but reasonably priced sources of ferrite for FSLs?-FARMERIK


Gary DeBock
 

Hi Max,

<<<   I haven't seen your document before, very interesting, same area same performance, this makes everything much easier.
I have read that the length of the rod should not exceed too much the length of the coil in a single rod antenna but this doesn't seem to apply here and the tests wipe out any doubt.   >>>

Thanks for your comments on the FSL Design Optimization article, and I'm happy that it was useful for you. I have also uploaded the file to our Ultralight Experimenters group site, and hope that it will be helpful to other FSL antenna enthusiasts in understanding how the factors of coil diameter, ferrite length and ferrite shape work out in the gain determination.

<<<   You mentioned some Russian rods with permeability 400, i think the others have permeability 125; did you notice any difference caused from different permeability of the ferrite (if you tested ferrites with the same size but different permeability)?   >>>

At the time of the experimentation (2012) almost all of the ferrite rods and bars available on eBay (at least for the reasonably priced Russian surplus material) was of 400 permeability, so all of the 7 FSL test models were constructed with that ferrite. Currently there is a wider range of permeability in the ferrite rods up for sale, but ferrite permeability was not one of the variables tested during that 2012 experimentation. In 2012 we did have quite a selection of different Litz wire types available, but at that time the largest size commercially available was the 660/46 Litz wire, so that was the type used in all 7 of the FSL test models. In 2015 the new, higher (MW) sensitivity 1162/46 Litz wire became available, so all of my new FSL designs since then (including the "Frequent Flyer" miniature FSL's) use this higher sensitivity Litz wire.

<<<   Also i would like to understand how much the type of wire makes the difference. If normal wire is used instead of Litz, can the lower performance be compensated increasing the diameter of the loop?   >>>

In all cases the highest count of individual #46 strands in a Litz wire type will always result in the highest MW sensitivity. As such, the 1162/46 Litz wire will be superior to the 660/46 Litz wire, and the 660/46 Litz wire will be superior to the 330/46 Litz wire, etc. The use of solid conductor wire was actually Graham Maynard's original FSL coil material in 2011, but detailed testing among the three original Ultralight group experimenters (Steve R., Kevin S. and yours truly) revealed that it had significantly less sensitivity that 330/46 and 660/46 Litz wire. In 2012 our fanatical group of three were going all-out for maximum gain, and we shared information about how to achieve it (much to the delight of the Ukraine ferrite sellers on eBay, who must now be enjoying early retirement).

Gary

      

      


-----Original Message-----
From: Max Italy <max2013@...>
To: main <main@UltralightDX.groups.io>
Sent: Mon, Feb 4, 2019 7:58 pm
Subject: Re: [UltralightDX] Reliable but reasonably priced sources of ferrite for FSLs?-FARMERIK

Hi Gary, i haven't seen your document before, very interesting, same area same performance, this makes everything much easier.
I have read that the length of the rod should not exceed too much the length of the coil in a single rod antenna but this doen't seem to apply here and the tests wipe out any doubt.
You mentioned some Russian rods with permeability 400, i think the others have permeability 125; did you notice any difference caused from different permeability of the ferrite (if you tested ferrites with the same size but different permeability)?
Also i would like to understand how much the type of wire makes the difference. If normal wire is used instead of Litz, can the lower performance be compensated increasing the diameter of the loop?

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