Re: Coil Winding Advice

Gary DeBock

Hello Phil,
Welcome to the group, and thanks for your interest in the coil winding technique used here in the PL-310 loopstick experimentation.
In answer to your question about the type of tape used to hold the Litz wire turns in place, I use Johnson & Johnson waterproof 2" wide tape, as pictured in the photo below.
This tape is wide enough to cut a piece slightly longer than the length of the planned coil, then wrap in an overlapping pattern on a half inch diameter ferrite bar, with the adhesive side out. In the photo above, this tape was used as the form for construction of an E100 Slider coil, with a half inch router bit shank used as a temporary base (assisted by a thin strip of a plastic credit card, to ensure that the coil was not wound too tightly). After winding, the strip of credit card was pulled out, providing a Slider coil that was "not too loose, but not too tight."
This waterproofing tape is excellent for holding the coil turns on experimental loopsticks, and was purchased from about 2 years ago, when I was able to get a lifetime supply. If you have trouble tracking it down, let me know, and I may be able to send you a small supply to meet your needs.
73 and Best Wishes,
Gary DeBock (in Puyallup, WA)
In a message dated 12/27/2009 10:35:06 A.M. Pacific Standard Time, writes:


Hello to the group.
I have beenlurking here for awhile, as I do in a dozen or so radio related groups. Just as a matter of perspective, I built my first crystal set in 1958. I have somewhere around 40 radios and maybe a dozen of them are ultra light class radios.

I recently purchased a PL 310 and honestly have been pretty happy with the performance. Then I started reading about Gary's experiments with improved loopsticks for the 310 and 380. This got me to thinking about doing some experimanting of my own.

The problem is that I have not wound a coil in years and even then did not use litz wire now have access to the modern materials that we have today.

I have a few questions concerning the mod that Gary did for the stock PL 310 loopstick, and coil winding in geneeral. For the 310, I wonder what the material was that Gary used to wrap the ferrite rod before winding the wire. I had read (and BTW, I spent several hours searching on coil winding techniques) that a masking tape could be used with the sticky side out to hold the windings in place. This sounds good, but would seem to present some problems with keeping the tape tight on the bar and making a uniform base. The pictures of Gary's loopstick, on the stock bar, for the 310 seemed to show a different material. What is a good material to wrap the ferrite with before winding the coil to get a good even base that will stay put on the rod? I have some heat shrink tubing that would fit, but worry about the thickness effecting inductance.

As to the wire itself, how do people retain it when starting the winding process, and when it is finished? I would guess that a tightly wound coil will stay put, but holding the initial end in place when starting and the final end when finished would be required. I thought about hot glue, but was concerned about electrical effects.

What is the prefered method of holding the rod so that the wire can be easily and uniformly wound?

If anyone could provide some tips to help me get started and covering what I have asked, or anything that I have missed, or point me to a good resource, I would greatly appreciate it.

Phil Pasteur

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