Re: Experimental Help - Terry?

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

Original poster: "Jim Lux by way of Terry Fritz <twftesla-at-qwest-dot-net>" <jimlux-at-earthlink-dot-net>

very carefully <grin>

If what you want to do is measure RF current, (rather than power), then, a
bolometric scheme in the base of the secondary might be a practical scheme.
I'd use the brightness of a filament lamp, calibrated with DC.

----- Original Message -----
From: "Tesla list" <tesla-at-pupman-dot-com>
To: <tesla-at-pupman-dot-com>
Sent: Sunday, February 24, 2002 9:31 PM
Subject: Re: Experimental Help - Terry?


> Original poster: "Ed Phillips by way of Terry Fritz <twftesla-at-qwest-dot-net>"
<evp-at-pacbell-dot-net>
>
> > I'd say that a thermal detector is THE way that RF power is measured
> > (accurately)... Whether a bolometer or thermistor... The fancy detectors
use
> > balanced circuits that hold the detector at constant temperature with a
DC
> > current. The amount the DC current decreases (and the resistance..)
tells
> > you how much power is being dumped into with the RF.  Uncertainties in
this
> > sort of sensor are:
> >
> > 1) How accurately you measure the DC current
> > 2) How accurately you hold temperature (this one's easy, because it's
> > basically a nulling to hold it at a zero, rather than actually measuring
> > something...)
> > 3) RF mismatch.. The RF power has to really get into the load, and not
get
> > reflected back.  The connectors are a problem here..
> >
> > But, in any case, all those HP power meters use thermistor heads...
>
> How would you go about matching the HP 50 ohm thermistor head to the
> output of the Tesla Coil, so that the correct power could be measured?
>
> Ed
>
>
>