Coil Construction, was: [AMRadio] Fun with 4D32's...

Brett gazdzinski brett.gazdzinski at
Tue Jan 2 11:12:28 EST 2007

Thanks Larry.
How do you keep the spacing of the holes

Since the handbook says the antenna tuner is good
for 250 watts of AM, I would need to at least double
the size of things, from the #14 at 8 tpi, about
a foot or more long, to ?
#10, or #8, or thin copper tubing?

The coil has two 4 turn links in the center, 
by unwinding 1/2 a turn I think, the links are
in series for 160 to 40 I think, and in series
on higher bands, and tuned with a cap.
The outside coil is tapped for various bands
and tuned with 4 caps.
Balance is important, maybe hard to do with
a home brew coil..

I did not study the text, not sure if its supposed to
cover 160 meters, but if I built one, might
as well include 160...

I know I will need to make some sort of coil 
form/support to achieve a good balance.

I may try to get about 100 feet of wire fed with home
made open wire line, say #14 separated by an inch or
inch and a half? About 35 feet of open wire line, then
into 2 pieces of coax into the shack and tuner...


> -----Original Message-----
> From: amradio-bounces at 
> [mailto:amradio-bounces at] On Behalf Of Larry Keith
> Sent: Tuesday, January 02, 2007 9:50 AM
> To: 'Discussion of AM Radio in the Amateur Service'
> Subject: Coil Construction, was: [AMRadio] Fun with 4D32's...
> How to make a nice coil of the size needed?
> Well, I build coils by drilling Polycarbonate ribs, winding 
> the coil on a
> form, letting it expand and then threading the coil through 
> the ribs.  
> I may even have some pics around here..  And, if you are 
> looking for 3"
> coil, 6 TPI, 12 AWG, 10" long -- I probably have one in the 
> hamfest box.
> 73,
> Larry
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