Re: stranded wire primaries

[FutureT-at-aol-dot-com (by way of Terry Fritz <twftesla-at-uswest-dot-net>)]

In a message dated 8/19/00 7:18:48 AM Pacific Daylight Time, tesla-at-pupman-dot-com 
writes:

> > Original poster: "Jason Johnson" <hvjjohnson13-at-hotmail-dot-com> 
>  >  
>  >  I've seen several successful coils using stranded wire for the primary (
> TT-
>  > 42
>  >  etc) and I was planning on using one for a small demo coil, but when it
>  >  actually comes to bulding a primary like this I really don't have a 
clue 
>  as 
>  > to
>  >  how to tap it. 
>  >   
>  >  Ideas, suggestions, anybody?

Jason,

My TT-42 TC uses solid 10awg wire with rubber insulation, and
your are correct that tapping this is not easy.  My old 42" spark
TC used a form of 12awg stranded wire, having very fine stands.
Since this was a research coil, I just used to force a sewing 
needle into the wire as a tap point.  I was able to get away
with this due to the high surge impedance of the tank circuit.
During some tests using larger caps, the needle used to get
red hot.   

By the way, on my TT-42 TC, I simply have a piece of copper
wire forced against one of the turns, and it works fine as a tap.

I once build a small demo coil, using 14awg wire, and I used no
taps at all.  I simple first made a test primary, and tapped it in
some crude way, with scrap wire.  Then I knew how many turns
to use in the final coil.  I just connect the end of the wire to the
tank cap.

It should be possible to make a small clamp using metal, that
will snap over the wire for the tap connection if you want to use
tap points.  In this case, you'll have to remove the
insulation for about 1/2" at various spots for tapping.  I like to
stagger these spots about 1 1/2" or so for each turn, so that
no inter-turn arcing can occur.

Cheers,
John Freau