"Ed" wrote in message
. 192.196...

How big do you want it? Tell me and I will MAKE you a big coil. Three
inches is a pretty good size, but can go bigger.


I have a different question than the original poster had, for you. In
making those coils, What do you use up the center of the coil to both
insulate, and connect the lower mast and the upper whip? Assuming
standard 3/8" 24 threaded connectors.....

TNX

Ed K7AAT

Mostly brass 3/8" X 24 brass bushings OR machined bolts (Stainless steel)
driilled in the center to receive the whip/mast. I generally use the brass
bushings because they don't cost near what the SS does. Those specifically
made bolts make the cost of the antenna much higher & and the bushings work
well and are easy to replace if you should booger up the threads. That
doesn't happen often, tho. But it makes it easy for any ham to repair one
*IF* he should cross thread the thing. The center is black nylon that is
machined to provide an open coil AND a support for the windings. This is
done by turning a round cylinder of nylon to the correct diameter, then
milling out concentric
grooves {sort of like this ) } all round the form. This makes for both an
"open" coil as opposed to winding the turns flatly onto the round form AND
as a support for it. It then lets you clip onto the coil turns the same way
of Henry Allen's Texas Bugcatcher. Then I thread the ends of the form to
receive the bushings and secure them with SS screws so they can't slip. Then
I wind on the wire (usually #14 tinned copper wire) in the grooves so it
remains in place. I mostly make screwdrivers, but I make these for folks on
request. I guess it may because of the cost of a screwdriver OR because some
of us only operate a few frequencies or bands. It costs about half the
screwdriver (of which mine are quite a bit less in cost) $500 for a
screwdriver? WOW! I can't afford that, so I make a few antennas partly for
$$$, partly for fun. It IS supposed to be a hobby! I have made some for a
couple of Civil Air Patrol folks, one of which is on a building in Raleigh,
NC as a fixed-base antenna. Turns out, they have some restrictions on
dipoles, but the airport authority would only them do up a vertical. So, I
made a mobile whip for them and they had enough metal up there for a nice
counterpoise!
Email me under the "Reply" and I will send you a couple of pics if you
like. One CAN use bigger wire if desired, BTW.

73

Jerry
K4KWH