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>

Jeff:

> BUT... Don't take any LIVE measurements with
> this meter... although full featured, it's very
> electrically fragile. 

This is very good advice too!

Early on, I used my DMM with a Fluke HV probe to monitor the
DC voltage at the tank capacitor, at least until I noticed that the
display on the DMM kept getting messed up or even weirder
things would happen.

Eventually that DMM (an inexpensive Beckman) went weird
permanently.

It wasn't the HVDC that was the problem - the probe is designed
to convert that ... it was the induced noise and voltage and current
that was affecting the DMM.

The key here is the Fluke HV probes are high-impedance, high
resistance dividers.  The internal resistor in the probe is
1000Megohms and is designed to work with a 10 Megohm DMM
to give 1000:1 divider ratio, so the DMM is set to volts;
IE: 40V on the display is = 40,000V at the probe tip.

 As a check, the weirdness happened even when the probe was
not hooked to the tank cap ... the probe wires made a good antenna.

> The BEST voltmeter for TC work is a Simpson
> panel meter mounted in a small box with banana
> jacks for test leads. Never fails and can be used
> to monitor voltage drop and other live voltage
> measurements.

Indeed!  Now I use a simple panel meter and big resistors during
live TC work.  I put together a little web page with schematic and
info on it:
http://www.mindspring-dot-com/~ottalini/My%20little%2020KV%20Meter.htm

Even when monitoring the input AC current, I prefer a
panel meter or a clamp-on with a movement over a digital.

Kevin

>
> Original poster: "Jeff W. Parisse"jparisse-at-teslacoil-dot-com>
>