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Re: More New Coil

Hello everyone,
                 Richard wrote in reply.....

> >          After two coats of varnish I decided to measure the coil
> > more closely. The final spec. after winding (and some former
> > modification) is:
> > 
> > Former = acrylic skeleton w. single layer of 1/8" LDPE sheet over it
> > Dwire = 0.9mm (copper diameter)
> > H = 39"
> > D = 16.8"
> > H/D = 2.3 roughly
> > N = 1000 turns
> > TPI = 25.6 or thereabouts
> > L(meas) = 162mH
> > C(calc) = 23pF
> > Fr projected = 82kHz without top hat. I won't be checking this
> > parameter until after all varnish has been applied (about 2 weeks).
> > 
> >     Winding was not without one or two slight technical hitches (most
> > notably barely avoiding wire bunching) but generally looks OK. Here's
> > to a bit of serious coilin' in the not-too-distant future.
> >     I am hoping to have a go at metal spinning some terminals for it
> > and that'll probably be the next item on the agenda.
> > 
> > Malcolm
> 
> 
> Malcolm, sounds like a "killer coil".  With that inductance it will 
> perform no matter what for it has a "large momentum" as Tesla would say. 
>  I would imagine that at least a 50-80pf top hap would really make the 
> thing sing in the white hot arc chorus!  It'll work at 5KW with little or 
> no load, but won't sing well with the big load until about 10-15KW is 
> applied, I would think.  Good luck and keep us informed.

Will do. Actually, if I was living in the States and suffering my 
parlous resource problem I'd willingly haul the thing around to your 
lab for serious testing on the good caps and high power transformers 
you have. In some respects I'm basically stuck in the mud, esp. with 
the prospect of having to return my CP caps. That being the case I 
may just use the time to develop a MOSFET driver for it plus I still 
have to buy pipe for the primary and do something about terminals 
anyway. The proposal is to bring it in around the 50kHz mark with 
about 45 - 50pF. Be interesting to run it at 45kHz though if poss.
     Anyhow, if things look OK in some lower power runs, the recipe 
is there for anyone that wishes to duplicate it. I would rather have 
used a "standard" pipe former had I had the material available. 
Interesting to note how an additional 20mH or so was so easily 
arrived at through a few more turns than originally thought plus a 
minor diameter increase.

Regards,
Malcolm