Re: [TCML] ANother tube coil question

[futuret@xxxxxxx]

David,

Yes VTTC primaries tend to run hot.  Ed Wingate now
uses litz wire on his primary, and he said it runs
a lot cooler after making the change to litz.

I usually use 12awg solid or stranded wire for
sparks up to 36" long. I don't keep my runs all
that long, so it works OK.  It's a good idea to
measure the input power and compare that
to the obtained output spark length.  It should
take about 2400 watts to obtain 24" sparks.

I use the formula:

  spark length (inches) = 0.5*sqrt input power (watts)

for VTTCs

Cheers,
John
----------------

-----Original Message-----
From: David Rieben <drieben@xxxxxxxxxxx>
To: Tesla list <tesla@xxxxxxxxxx>
Sent: Wed, 10 Sep 2008 10:27 pm
Subject: [TCML] ANother tube coil question



Hi all,

I have been having a bit of trouble lately getting my
VTTC back up and staying running. I flashed over the
primary to the secondary coil yesterday and damaged
the secondary enough that I am just going to have to
wind another one. I tried to rewind with #22 wire that
I already had laying around on a longer form but it still
turned up being WAY out of tune as the original se-
condary was about #26 or possibly #28. I tried winding
some old #28 or possibly #30 from an old secondary
bobbing from a dismantled x-ray transformer, but it was
unusable for rewinding as it had a bunch of glue and
kraft paper stuck to the wire which caused it to wind
poorly and to snag and break easily. So it looks like I'll
be having to either buy some more #28 magnet wire or
else just buy a prewound secondary coil of the same
approximate demensions and wire guage, as they ap-
pear fairly plentiful on eBay.

Now my question is do you other vacuum tube coilers
have trouble with your primary coils getting really hot
after just a minute or two of operation? I was originally
using #10 for my primary but it was getting practically
smoking hot and I ended up replacing it with #6. The
#6 still gets quite warm after a minute or so of firing,
especially in continuous mode. I'm wondering if it's
more inductive heating going on here than resistive
heating as the leads to the primary coil are of the
ame guage but don't seem to get near as hot.
My VTTC is ran off of (2) sereised MOTs into a
level shifter and an 833 tube with 8 uFd of filter caps
in the shifter and 5 nFd in the primary tank cap.

Thanks,
David

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