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Re: 3000 turn secondary
Hi Marc,
Tesla list wrote:
>
> Original poster: "Metlicka Marc" <mystuffs-at-orwell-dot-net>
>
> Tesla list wrote:
> > Hi Marc,
>
> 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.
I know exactly what your talking about with the "hind-sight". When I first
built my 12" coil, it was 34" high. I later went to buy an add-on form and
found ALL different sizes. They vary greatly! I used a tape measure to get the
right diameter (which I found to be 12.75").
>
> 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 have and have not. But someone posted recently (last month) that they removed
their strike ring and blew up a filter. So, it couldn't hurt. In my mind, the
verdict is not yet in.
>
> 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?
I always mount caps directly under the primary to keep primary inductance to
some known "design" value. You could get away with mounting it in a control
mod, but the inductance of the line to the primary is "part of the primary" and
will need to be accounted for. I'm not sure if there will be added problems
doing this.
>
> 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?
Yes, it should.
>
> also, i am winding the coil with 5" dist. from the
> topload
> to the last turn, does anyone think this to be to much?
Should be just about right. I space wind the last 5 turns with about an inch
spacing. You might want to do this up to the toroid connection. I'm not real
sure that it makes a big difference, but I did this from posts a few years ago.
Haven't even though about since. There will still be an overhang due to the
cord diameter of the toroid which should provide plenty of ozone shielding of
the top turns.
>
> 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?
Assuming it's non-conductive and there are no conductive properties molded in
with the plastic, it should do just fine. I've seen these myself walking
through the garden department, but my form was about 1/4" too wide for them.
I'm glad to hear you taking on this task. We should all discuss the spacewound
coil. There are several methods to spacewinding a coil. Personally, I think you
should spacewind the coil with the same number of turns keeping the inductance
as close as possible between coils. This will make the form a little taller,
but... I don't know, what does anyone else think? I'll have to run some more
numbers and look at the frequencies. I would like to see all the coils at the
same resonant frequency. Sd should be the same between coils and proximity
losses can then be quantified accurately.
Take care Marc,
Bart
(BTW, Malcolm I'm still waiting for the generator. May be best to do the test
this weekend. I may have to break down and get my own).