Tips for Winding the E100 Slider Coil


Gary DeBock
 

Hello Guys,
 
     As most of you are aware, a new type of AM loopstick was developed this summer for use in the E100 Ultralight and other single-coil designs, in which the loopstick coil is shifted by the DXer to peak each incoming signal on its own frequency. This simple innovation makes a huge difference in the sensitivity of the radio on all AM frequencies, making it competitive or superior to all of the most popular portables in AM-DXing history.
 
     For those DXers wishing to construct a Slider loopstick for their E100 or other portables, one of the challenges is winding a coil of 40/44 Litz wire that will slide easily on a type 61 Amidon 7.5" ferrite bar, but not "too easily."  The early designers of Slider loopsticks (John Bryant and I) faced this problem, and we both developed our own solutions.
 
     Although John certainly has his own procedure, my own trick is to wind the coils on a form of waterproof tape, wrapped tightly around the most slippery half-inch diameter material I could find:  the long, half-inch shank of a router bit.  In order to ensure that the coil will be very slightly larger than .5" in diameter, I place a 3" long, 1/16" wide strip of a cut up credit card lengthwise on the router bit shank, before winding the coil.  This strip of the credit card is pulled out after winding the coil, to ensure that the coil will easily slide off the router bit shank.  If all goes well, the coil will slide easily, but not too easily, on the half-inch diameter Amidon ferrite bar.
 
     Should the coil slide too easily, it is a simple matter to cut thin strips of the waterproof tape and place them lengthwise inside the coil (adhesive side out), until the coil "drag" is ideal.  The Type 61 Amidon ferrite bars also have slight ridges lengthwise from end to end, which allows the DXer to rotate the coil slightly to find the ideal "drag" position (as long as the pre-wound coil is approximately correct in inner diameter).  Good luck!
 
     73,  Gary DeBock 
 
 
  
 
 



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