Re: New style of FSL........I think ?

Tony Magon

Hi Dean

How many turns of litz is required - or what is the length of Litz wire required


Tony VK2IC

On Mon, Dec 2, 2019 at 11:41 AM Dean wayman <dx_plains@...> wrote:

Because of the rising cost in Ferrite and Litz wire I have been thinking for some time about building a FSL that uses less .
It seemed to me that the wire part of the FSL is mostly fixed ,so maybe less ferrite in some way would be cause less stress on the pocket book?
After looking at everything on the net ,Pics of loops ,Gary's massive collection ,other peoples builds and all ,I decided to see if a spider weave or Basket weave was practical?

I made a 3 inch circle from wood and put 9 ,8x80mm Ferrite rods M400  on it , I have no pic of it . To this was added some turns of 1200/46 litz, And a variable tuning cap of 14-465 pF .This tiny loop worked very well giving a good boost in signal strength ,The nulls were very deep and sharp.

So I cut a plastic pipe of 4 inch size ,and installed 15 of the same size rods on it. Again 1200/46 Litz was wound on this .

I also wanted a pickup loop to set next to the radio ,because this loop would need to be mounted to some thing in the vertical plane ,so that it could be rotated to line up with different stations on the compass.

2 configurations were tried the first was 

This winding proved to be very difficult to produce and ,not of much benefit ,seemed to make the tuning on the loop mushy even adding bass to the signals,so it was abandoned.

The next was this, 4 turns at the center and then the loop winding and finally 4 more turns over that to complete the pickup coil.

A inner and outer winding was made of 660/46 Litz, terminated to a 1/4 inch Mono phone jack so the pickup loop could be removed for mutual coupling or transport etc.

Up to now I had  used 2 weeks of nearly full days testing, building ,rebuilding etc.but one more thing needed to be explored ,on this loop do you need space between the Ferrite and litz?  I'M not trying to start any arguments etc. but I needed to know ,So this was unwound and spacers were added to the Ferrite ,clear plastic hose worked just right .Everything was re-assembled for testing ,And a second loop was wound directly on the Ferrite rods ,this part of the whole experiment needs more work but so far I see no difference in gain.

Another test loop was also built on wood dowels and a center circle to use as a control to test Ferrite vs non Ferrite .As we would think the ferrite gave more boost of signal.

Several days later it was taken to a quiet location ,in testing it has very good nulls which are deep and gives plenty of boost to signals.
Comparable boost with my 6 inch flat wound loop ,,and easier to use because the radio sits near me and  needs no lazy-susan .

So I leave it to you ,If your looking to spend a bit less and have a decent antenna maybe give it a try ?

Test radio's
Tecsun PL 600
Sangean 909 X


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