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RE: Fluke 27 and Transformer Oil

One important point that I should have added to my original post, is that
while it is fine to measure your NST's current with a DMM on the bench this
way, do not try to do anything with a DMM when the NST is powering a RUNNING
coil.  I tried metering the NST secondary current on a running coil with my
Fluke #27 (slap me now).  The display wigged out and I had to power it off
and on, and I think it was just luck that it worked afterwards.

Regards, Gary Lau
Waltham, MA USA

		-----Original Message-----
		From:	Lau, Gary 
		Sent:	Friday, December 24, 1999 10:16 AM
		To:	'Tesla List'
		Subject:	RE: Fluke 27 and Transformer Oil

		Hi Nathan:

		You can use your DMM to measure the NST current, that is the
same model that I use.  Since measuring the current essentially places a
short across the NST, the voltage is nearly zero and not a problem for the
meter.  But you should still keep your hands clear, just in case something
opens up.

		With a 15/150 power supply, you could use a cap considerably
larger than the mains-resonant .02uF value, though that will certainly work.

		The voltage that a cap sees is almost solely determined by
the gap setting.  I could run a 15/150 NST with a 0.1" static gap and the
voltage would never get higher than 8KV or so (ROUGH estimate).  Your caps
would be happy forever.  But if you used a 7.5KV NST with a mains-resonant
cap and a gap opened to 0.75", it may ring up to over 50KV.  Your caps would
be toast.  

		I think for a reasonable gap setting, one that would perform
to the potential of your very considerable power supply, a single 0.048"
poly dielectric is way too small, particularly for just a single unit (as
opposed to two or more in series).  I burnt out a cap made from two units,
each with .040" poly, with a 15/60 NST and a .34" gap.

		Regards, Gary Lau
		Waltham, MA USA

				-----Original Message-----
				From:	Tesla List [mailto:tesla-at-pupman-dot-com]
				Sent:	Thursday, December 23, 1999 1:51 PM
				To:	tesla-at-pupman-dot-com
				Subject:	Fluke 27 and Transformer Oil

				Original Poster: "Nathan Ball"
<nateburg-at-hotmail-dot-com> 

				Greetings!

				I am Nathan Ball, 16 year old coil builder
and new to the list.

				I have a couple of questions:

				I have access to the use of a Fluke 27 DMM
and was wondering if there was a 
				way I could use it to measure the output
current on the 15/30 NSTs i 
				rebuilt.  It says in the manual that the max
input voltage for AC mA is 
				600V...

				Also, I am building some new capacitors that
will add up to 0.0265 
				microfarad to match the new power supply of
15/150.

				I built a 0.0053 uF cap before and used 8
sheets of LDPE between each plate. 
				  I have since seen most people using at
minimum 60 total mils and mostly 
				aroun 80-90, but I have never had any
problems running a 15/30 through it.

				I think it may be because of the extremely
pure transformer oil I got to put 
				it in... but do you guys think 0.048 inches
is enough for a 15/150?

				Thanks in advance!

				Nathan Ball
	
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