Re: impedance meter - Wavetek 27XT

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

Original poster: "Kevin Ottalini by way of Terry Fritz <twftesla-at-qwest-dot-net>" <ottalini-at-mindspring-dot-com>

Thanks Luc ... My Fluke runs ok at DC and 60Hz but not much higher.  I use
a  calibrated Tek HV probe (P6015A) for more serious stuff at up to 20MHz.

I did build two 240KV AC/DC probes using caps and resistors that I'll
document someday (tradition design, nothing special, 8 stages of
200megohm resistors and 500pf, 30kv caps), but it was a little
awkward to handle so is waiting on a redesign.

I sorta like the helical approach that is used so often in professional
HV designs ... wrap the RC string around a tube or inside a tube with
SF6 gas or oil or epoxy or whatever.

I was hoping to eventually get a design that would work up to a million
volts or so, but that needs amplification on the bottom end or the load
on the top will be terrific! (1million volts at 100uA (my most sensitive
meter) is 100 watts just to power the meter!).

I'm thinking that I can get the voltage down to around 3kv and then
use a small transformer to drop the voltage and multiply the current.

Also, the capacitive string of the 240kv probes ended up at about
62pf ... enough to dramatically change the resonance of a secondary.

Best,
    Kevin

----- Original Message -----
From: "Tesla list" <tesla-at-pupman-dot-com>
To: <tesla-at-pupman-dot-com>
Sent: Sunday, July 29, 2001 9:22 PM
Subject: Re: impedance meter - Wavetek 27XT


> Original poster: "Luc by way of Terry Fritz <twftesla-at-qwest-dot-net>"
<ludev-at-videotron.ca>
>
> Hi Kevin
>
> I have some resistor like the 20 meg you use in your meter, mine
> are 220 meg, they are find for 60 cycle but will give you false
> reading if used at high frequency because they have to much
> inductance. You could built your resistor your self
> MultiMiniResistor ;-) in one of these patterns:
>
> /\/\/\/\/\/\/\
>
> I use this pattern too before see:
> http://pages.infinit-dot-net/luc2/no_induct.r.gif
>
> But I think the zigzag pattern is better.
>
> cheers,
>
> Luc Benard
>