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RE: Simple Helix for Mode S

Hi Robin,

The simplest design I've seen so far (credit to Howard Long G6LVB) is to 
make the helix out of #10 or #12 solid copper wire, an N-connector, and the 
bottom of a 4" tin can.  Look towards the bottom of 
http://home.jps.net/~gregd/hamsite.htm (skip the first attempt, which did 
not work well).  The critical parameters are for one loop to take 146mm of 
wire, and space them 32mm center-center.  I marked the wire at 146 mm 
increments, and wound it around the cardboard tube from a paper towel for 
starters.  Twist and stretch it to get the 146mm lines to line up, properly 
spaced; don't sweat the diameter, it will take care of itself.  Then cut it 
to length, and solder it to the N connector as low on the center pin as you 
can get it without shorting things out.  I understand that odd multiples of 
1/4 turn is best (so, 5 1/4 turns or 5 3/4, not 5 1/2).

Good luck,

Greg  KO6TH

I'm sure this has been asked before so sorry in advance for the repeat......

Can anyone send me a pointer to the dimensions or construction details for a
helix for Mode S. I did a google search but it didn't turn up much.....

probably better to send to me directly rather than spam the whole group.


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