Concentric Coil Question

[Gary]

I'm Curious as to why, in concentric designs, the recieve coils always seem to be 1/2 the diameter of the transmit coil.
Why not 2/3's or 3/4's?

Is there a reason for this?

Also, is it recommended to put the cap that parallels the recieve coil, in the coil assembly, or on the pcb.
Or doesn't it matter either way?

Take care.......Gary

[Beachcomber]

Re: Concentric Coil Question

Actually I think it is more a matter of what the manufacturer wants to do. If you look at Fisher Concentric coils thier receive windings are about 2/3 the size of teh transmist winding. But if you look at Troy's 9" coil for the X-5 you will see that the receive winding on that coil is only about 1/3 the diameter of the transmit winding. I also have an old Teknetics 10" open loop Concentric coil for the Mark I and it's receive winding is 2/3 the diameter of the transmit winding. I don't believe that there is any hard or fast rule about the size of the diameter of teh receive winding with respect to the transmit coil diameter. As I ahve been thinking about trying my hand at making a 12" Concentric coil over the Winter I find myself taking much more notice of things like that lately I don't know the answer to your capacitor question.

I would like to know how you determine the number of turns for the bucking coil. Is there a forumal or ratio between the number of turns of the transmit winding and the number of turns in the bucking coil? Maybe someone who reads this will know the answer and Post it here!!!

Thanks

HH

Beachomber

[Gary]

Re: Concentric Coil Question

Thanks for the reply.
And as to your question: It was explained to me that if the recieve coil is 1/2 the diameter of the transmit coil, that is 1/4 the area. Therefore if the bucking coil is wound directly over the recieve coil, it will be 1/4 the turns of the transmit coil. And it is very close on the two I made.

I have also found that if the bucking coil is slightly smaller than the recievecoil, it will than be close to half the turns of the transmit coil.

Hope this helps, take care....Gary

[Beachcomber]

Thanks Gary!! It does!!!

HH

Beachcomber