Re: 3000 turn secondary

["Metlicka Marc" <mystuffs-at-orwell-dot-net> (by way of Terry Fritz <twftesla-at-uswest-dot-net>)]

Tesla list wrote:

> Original poster: "Barton B. Anderson" <tesla123-at-pacbell-dot-net>
>
> Hi Marc,
>
> Tesla list wrote:
> (sniip)

bart, malclm, john, all
after digging the spool out i found that it is a 9 pound spool. john f.
gave me a
suggestion of winding the 3k coil and maybe a 2.5k or 2k one for
comparison, and
your suggestion sounds good also. so i started winding the 3k coil tonight, i'm
winding by hand with a rolling jig so it will take a while. after i get it
done, if
it works well, i will wind a 2k coil same dia. (which i finally put a tape
measure
to and found out it has a 8.75" outer dia.. hind sight 20/20 on me) for
comparison.
then if there is a substantial difference i will try a space wind for that
comparison also. power supply will be the same on all coils and topload so it
should be interesting for sure. the one thing i was thinking about is that
with a
33" primary od. 43" or so from the 30" toroid, should i use a strike ring?
i just
bought this beautiful 52nf 55kv cap that fits perfectly into my cabinet
with the pt
and controls so i would hate to loose it? but for the sake of knowledge! i
had to
bump the id. of the primary up to 12" for clearance, but some how the
inductance
climbed when i did this? also, i am winding the coil with 5" dist. from the
topload
to the last turn, does anyone think this to be to much? and i found a metal
lid for
a pot that fit perfect into the top, see any problems with using this for the
topload mount? or will it attract problems down the road?
i'll keep all posted on this and any more input would be great,   marc

>
> The design sounds fine. It looks like you'll need about 3 lbs. of wire, so a
> twin coil is very probable out of the same spool. I took a look at what would
> occur if you space wound the coil with a spacing of half the wire diameter
> (.0063"). It would then require 2000 turns. Your frequency would increase to
> around 59kHz loaded. You have a couple things going on if you do this. You
> increase the skin depth losses, but you decrease the turn to turn proximity
> losses. I'm not sure which one would be best over the other. Another occuring
> feature is you'll go down to about 16 turns on the primary increasing gap
> losses. I'm not sure if the changes are small enough to really make much of a
> difference between the two. As much as I would love to see you space-wind the
> coil, it's ultimately your choice to do what you think is best. Of
course, one
> way to tell is to wind two coils (one close wound, one space wound, and make
> the comparison). The space-wound coil would take about 2 lbs. of wire, so
maybe
> enough left over for a third coil!
>
> Just throwing a couple pennies your way.
> Bart