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RE>Re: High-Bandwidth Prima (fwd)
---------- Forwarded message ----------
Date: 30 Apr 1998 13:31:20 -0700
From: Dale Hall <Dale.Hall-at-trw-dot-com>
To: Tesla List <tesla-at-pupman-dot-com>
Subject: RE>Re: High-Bandwidth Prima
RE>Re: High-Bandwidth Primary Circuit Behavior (fwd)
Terry,
I concur w/Gary re: the 10K WW. Have you measured their inductance ?
Alternatively replace each one with 5ea 2k 2W carbons and retest.
While subtle, the NST L&C&R's should also be included for thorough analysis.
Re: your photo of the Neon and filter system, what is the "what looks like a
vertically mounted toroid" with 2 wires in and 2 wires out ? (looks like an RFC
differential filter inductor on output of NST? and not appearing in schematic)
Is ball bearing appearing array of 5 gaps on each half the protection gap ? While multiple gaps may aide in quenching in the Pri, what is their need in
NST protection ? (heat spreader? or ?)
I too was concerned about the 150pF as being way too high.
Look closely at the test methodology, Cp distributed shouldn't be > few pF
even though you're using a very large Pri (120uHy).
Suggestion: If you have some ferrite cores laying around, try placing them on various leads to dampen the HF oscillations. Prudent placement may
direct you to the precise source and resulting enlightenment on HF behavior.
I'm curious as to change in results when secondary load is added to Pri. +
Result delta with various controlled Sec gap spacing to vary the load & timing?
I would like to see the test with a HVDC supply and Vacuum relay / switch /
interrupter. (Jennings, Kilovac) with the latter the most interesting.
Do you have access to these ?
Your work here may also have application in more detailed understanding of the
contact erosion mechanism when switching/interrupting inductive loads (they
likewise see a damped sine decrement as they open and require snubbers to
integrate the high peak current pulses to lessen damage).
Following the tests & thread with much interest,
Dale
------------------------------
Date: 4/30/98 11:42 AM
To: Dale Hall
From: Tesla List
---------- Forwarded message ----------
Date: Thu, 30 Apr 98 14:17:10 EDT
From: Gary Lau <lau-at-hdecad.ENET.dec-dot-com>
To: tesla-at-pupman-dot-com
Subject: Re: High-Bandwidth Primary Circuit Behavior
>I have written a paper on all this. It is available in Word 97 formated
>as an HTML web document at:
>
>http://www.peakpeak-dot-com/~terryf/tesla/experiments/experiments.html
Terry,
In your "New Model" of the primary circuit, you have the self capacitance of
the primary inductor as 150 pF, measured by finding it's self resonance.
I tried the same on my primary, 13 turns of .25" copper tubing, 15 degree
saucer, ~6" ID. I found the strongest resonance at 24MHz, suggesting a self-C
of only 0.75 pF. Considering my 4.25" x 22" secondary only has about 9 pF of
self-C, I'd say 150 pF for a primary is way too high.
There must be something else in your rig resonating at 1.2MHz. I wonder what
the ESL of the tank cap is and how to measure that? But then, that wouldn't
ring when the gap opens. How about your (wire wound) protection resistors?
Regards,
Gary Lau
Waltham, MA USA