RE: 60kV 50MHz HV Divider Completed

["Tesla list" <tesla-at-pupman-dot-com>]

Original poster: "Lau, Gary by way of Terry Fritz <teslalist-at-qwest-dot-net>" <Gary.Lau-at-hp-dot-com>

Hi Dan,

I couldn't tell from your schematic what type of caps were used for the 82 
pF compensation caps.  My assumption is that they are ceramic.

I once attempted to build a purely capacitive HV divider, also using 
ceramic caps on the HV side.  When I attempted to scope the output of an 
NST, the resulting voltage was grossly different than what the capacitive 
ratio should have produced.  I mentioned this on this List, and I think it 
was Bert Hickman who pointed out that ceramic dielectrics have an 
unfortunate property of creating a capacitor that's voltage-dependant.

This effect may be less evident if the dominant division is achieved with 
R's rather than C's, just something to keep in mind (and something that 
simulation models don't account for).

BTW, your Marx generator is BEAUTIFUL!  What did you use for the gap 
electrodes?  Are the support plates for the electrodes constructed so that 
they are hinged and may be adjusted in unison?

Regards, Gary



  -----Original Message-----
From: 	Tesla list [mailto:tesla-at-pupman-dot-com]
Sent:	Thursday, May 15, 2003 1:45 AM
To:	tesla-at-pupman-dot-com
Subject:	60kV 50MHz HV Divider Completed

Original poster: "by way of Terry Fritz <teslalist-at-qwest-dot-net>" 
<dhmccauley-at-spacecatlighting-dot-com>

I finally got around to completing my 60kV High Voltage Divider.  The design
works extremely well (from initial tests) and should serve as a good
baseline for others wanting to build hv dividers capable of high frequency
measurements.  The frontend features a combination resistive/capacitive
divider and
a additional box which attaches to the unit to allow fine adjustments of the
gain/frequency compensation of the entire hv divider.

http://www.spacecatlighting-dot-com/hv_divider.htm

Specifications:
Maximum voltage:  40kV-60kV (construction dependent)
Bandwidth: 54MHz (simulated 3dB roll-off)
                    50MHz (measured using impedance analyzer)
Ratio: 1000:1

Enjoy!

The Captain