Re: Bypass caps and Neons
From: D.C. Cox[SMTP:DR.RESONANCE-at-next-wave-dot-net]
Sent: Tuesday, December 09, 1997 12:02 AM
To: Tesla List
Subject: Re: Bypass caps and Neons
RF chokes are always required. A value of 1 1/2 in dia with around 60
turns works fine to clip the very high frequencies. Then a good power
resistor is required between the RF choke and your transformer bushing --
as you already have. The caps are usually optional but cheap insurance.
We use 3 -- 500 pF "doorknob" type caps in series (total 167 pF at 60 kV)
off each bushing to ground with a 20 watt, 10 Ohm resistor in series
between the lower end of the doorknob stack and ground. The RF chokes grab
the HF, the resistors spoil the Q factor, and the caps act as a direct
ground path for HF currents. Another tip is be sure to keep your TOTAL gap
around 0.200 to 0.250 inch when using NST's. All these components together
should provide long life from a NST in good condition to start with. On
ocassion you will fry a NST but many times it was "tired" to begin with if
it is an old, used unit.
> From: baumann-at-proton.llumc.edu[SMTP:baumann-at-proton.llumc.edu]
> Reply To: baumann-at-proton.llumc.edu
> Sent: Monday, December 08, 1997 7:16 AM
> To: tesla-at-pupman-dot-com
> Subject: Bypass caps and Neons
> Looking for advice from more than one source:
> I am getting conflicting advice, and so I am asking here.
> Does one, or does one not, need bypass caps when using neons?
> Currently, I am using a pair of bottle caps as bypasses, and I had
> just made a couple of 500pf poly caps to replace them. Then I found
> a message from Richard Quick, stating that bypass caps should be
> very lossy WRT HF energy., so I'll use these caps in parallel with my
> 6nf cap on my coil, and stick with my saltwater caps for the bypass.
> I have also gotten advice to just avoid the caps altogether, as you can
> fry a neon with unwanted resonance.
> Needless to say, I am confused. Any light that could be shed on this
> would be very welcome.
> Particulars on the coil in question:
> Power: 12KV 30ma NST controlled with 140V/10A variac.
> Choke + Resistor: 3.2mh air core [6" of 28g on 2" form], 1K 50w
> wirewound resistor [ for another 2.7 mh of inductance BTW]
> Tank circut: 12G wire for interconnect, 9 turns 1/4" copper pipe,
> starting at 5.5" diameter, with 1/4" spacing, 6nf homebrew poly
> capacitor, 7 element RQ style static gap, spaced at .030, total gap
> is .18"
> Secondary: 3.5"x10"x24g
> Toriod: 3" x 12" (pie pan + 3" flex ducting)
> Michael Baumann Optivus Technology Inc.|Loma Linda University Medical
> San Bernardino, California. (909)799-8308 |Internet: baumann-at-llumc.edu