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RE: 3-1000z coil, more questions
Boring?! Heck no! this is what we live for, isn't it?
On Mon, 31 Jul 2000, Tesla list wrote:
> Original poster: "Ross Overstreet" <ross-o-at-mindspring-dot-com>
> Hi Malcolm (and gang),
> I measured the wire diameter at 0.021" with a micrometer. I guess
> experimental results of 400Hz and a theoretical of 375 isn't too bad
> (6.25%). I'm just spoiled since my previous coils came out so close...
> As the schematic indicates, I wanted to try filtered DC for the 1st mode of
> operation because I eventually want to audio modulate it and I think the ion
> motor trick is neat. I'm not completely sold on DC and could just as well
> start out with AC or level-shifted.
> Are there logical reasons why I should try one before the others? Maybe
> straight AC because it has less components?
> I'm still reading the responses and trying to process all the info...
> David - I have about 12 of the panasonic MMC's laying around. I'll make a
> single string out of 'em and get the C down around 4.6nF. That will drop my
> primary turns down to around 13.5. The primary tank DOES have to oscillate
> at the same freq as the secondary, right?!?
Of course your right. BUT, one big gotcha! Watch your primary impedance,
as you do have to match the impedance of the tube. I used 0.01 & 0.015 uF
Panasonics, as those values work out a little better. A single string
still does get warm, but two is about ideal. You will probily need more
primary turns, so I would recommend getting more Panasonics. You may want
to try to drop your primary capacitance down to ~2nF, so something like
two strings of 11 (? just guesing as I don't have my handy MMC excel calc
sheet in front of me) of 0.01 uF caps.
> I'm making the grid coil so that it can easily slide up or down the primary
> former to adjust coupling.
> Thanks for the help! Hope I'm not wearing on anyone's patience with this
> thread b/c there are more questions to come. I'll try to put up fresh pics
> every major step in the construction to keep things from getting too boring.
> ---Ross wrote---
> > 1. My secondary is 4" x 23 5/8", wound with 0.021" magnet wire, and has a
> > measured resonant freq of 400 KHz. (This is surprising b/c Medhurst &
> > Wheeler predict it to be 375 kHz)
> ---Malcolm replied---
> How many turns are actually on it? The 0.021" is the copper
> diameter, not the outside diameter of the insulated wire.