HV Xfmr Protection networks

From: 	gary Lau[SMTP:lau-at-hdecad.ENET.dec-dot-com]
Sent: 	Wednesday, June 25, 1997 10:51 AM
To: 	tesla-at-pupman-dot-com
Cc: 	lau-at-hdecad.ENET.dec-dot-com
Subject: 	HV Xfmr Protection networks

All of the archived materials I've seen on this subject
recommends using 3-4 barium titanate doorknob caps in series
for the bypass caps.  I understand that these are considered
"lossy" at high frequencies, desirable in this application.

But is this necessary?  I was planning on making caps from
.09" thick fiberglass circuit board stock, easy to work with and
easy to get any reasonable value.  With a dielectric rating of
11.8 pf/sq inch (measured) and 700V/mil (from MATH.TXT), this
should be good to 63KV DC, maybe 30KV AC?  As I'm using OBIT's
which have a center ground, I'd use a pair of these caps,
shooting for ~700 pf each to RF ground.

For the safety Gaps, do these need to be anything more robust or
complex than a short piece of heavy copper wire at the proper (?)
spacing across each bypass cap?

Gary Lau
Waltham, MA