Re: Hi from a new member with a question. (coil spacing off the ferrite)


Steve Ratzlaff
 

Hi Steven,

As you note, of course air is the lowest loss spacer but it's not very easy to wind a coil spaced over ferrite using just air.     :)      Styrofoam is probably the next least-lossy dielectric, and can often be found in sheets of varying thickness where  a single layer or maybe several layers add up to the correct coil spacing. As for Litz, if you can obtain some, try to get as many strands of #46 gauge as your budget allows. I would suggest that a minimum of 100 strands of Litz be used (100/46) otherwise the improvement over using plain non-Litz wire won't be much. 175/46 and 330/46 are common sizes and are good choices, with 330/46 working better. And then there's the "Big Litz" such as 660/46 which works even better but which is much more expensive. Also remember the larger Litz is larger in diameter so make sure your coil form width can handle the extra winding width, and also that you will need somewhat more turns for the larger size Litz you use, to tune the same frequency range using the same variable capacitor since the inductance for a given number of turns will decrease the larger the wire diameter that is used.

Good luck and please keep us informed of your experiments and results! And it must be fun to listen to Radio Caroline live; you're fortunate to be able to receive the signal, even in daytime.

73,

Steve AA7U

Arizona, USA


On 1/29/2017 10:17 AM, Steven mont633@... [ultralightdx] wrote:
 
Hi,
Thanks very much for all the replies to my question.
I will remove the winding and add something to give the correct "air gap" to 1/4"-5/16", and see how that goes, I will also get a hold of some Litz wire as I have seen it on ebay.

I have been using my ferrite sleeve antenna most of the day to listen to Radio Caroline live from the MV Ross Revenge via Manx Radio in the Isle of Man on 1368 kHz AM.
I am over 100 miles from the Isle of Man, but with my ferrite sleeve antenna or one of my air core loops the ground wave signal is good readable at my location in Scotland.

Thanks very much again for the help and advice.
73
Steven.
Scotland.


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