NST protection

From:  Steve Falco [SMTP:sfalco-at-worldnet.att-dot-net]
Sent:  Monday, April 13, 1998 6:19 PM
To:  Tesla List
Subject:  Re: NST protection

Tesla List wrote:
> ----------
> From:  Sulaiman Abdullah [SMTP:sulabd-at-hotmail-dot-com]
> Sent:  Monday, April 13, 1998 6:25 AM
> To:  tesla-at-pupman-dot-com
> Subject:  NST protection
> For each side of the NST;
> Safety-spark-gap to ground ( 5 mm gap, 1" steel balls)
> 1.1 nF Ceramic to ground   (two parallel sets of 4 x 2.2 nF each)
> 7 kOhm 30 W wirewound resistor in series with
> 18.5 mH air-core inductor (0.4mm magnet wire, 109mm dia, 750 turns)
> Great (in theory).
> Surprisingly the safety-gaps fired before 100% on the variac,
> with no filter the gaps didn't fire.
> No problem, simulated resonant-rise on PC so decided to adjust gaps.
> Was it coincidence that the NST failed under the above conditions?
> or is a spark-gap (even a "safety" gap) directly across an NST a
> bad idea? Comments ? ............
> Bye ... Sulaiman

>From what I have read on the list, the 1.1nF caps were probably where
you went wrong.  They apparently can cause resonances inside the neon,
which cause it to overvoltage.  The spark gaps themselves should be ok. 
Ditto for the resistors and chokes.

	Steve Falco