[600MRG] Lightweight coil construction

Pat Hamel pehamel at cableone.net
Thu Jan 22 10:12:32 CST 2015


Some of you may remember that I used a suspended coil made of one layer of
boat-building fiberglass and flat copper tape on 600 meters for many years.
I used weed-eater line to take the weight of the lower part of the antenna.

Building a coil that can be suspended and lighter than mine just jumped out
at me when I was re-reading the first ARRL Handbook (which came with the
regular hardcover handbook I got a few years ago.)
The technique is called basket-weave, and should scale up to 630 meters
easily.

First calculate the ballpark inductance you need and the size of the coil.
The length and diameter should be the same for best "Q".
Mine was 16 inches in diameter and ended up slightly less than 16 inches
long.
Get your insulated wire and some tarred or otherwise UV-resistant tie cord
(net making cord is fine).
Get a board and a bunch of rods or dowels. Drill a circle of holes (an odd
number) on the board to hold the rods or dowels upright.
Fasten one end of the wire and wind wire in-and-out of the rods for two
turns. The wires should cross between rods. Tie them together where they
cross.
Weave your way up the number of turns that you need, tying them as you go.
Remove the dowels and you have a self-supporting, lightweight, low-loss
coil. 
Spray paint to match foliage and set the knots, and hang it.
My primary duty as caregiver has kept me from building the 600 meter SSB
exciter, but I still monitor and hope to be back on the air 
I hope this helps, 
73,
Pat W5THT & WD2XSH/6










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