RE: 3-1000z coil, more questions

["Ross Overstreet" <ross-o-at-mindspring-dot-com> (by way of Terry Fritz <twftesla-at-uswest-dot-net>)]

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?!?

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.

Seeya,
Ross

---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.