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Re: TC Electrostatics
Tesla List wrote:
>
> >From ed-at-alumni.caltech.edu Tue Dec 10 21:52:03 1996
> Date: Tue, 10 Dec 1996 18:11:53 -0800 (PST)
> From: "Edward V. Phillips" <ed-at-alumni.caltech.edu>
> To: tesla-at-pupman-dot-com
> Subject: Re: TC Electrostatics
>
> "If you shunt across your thermal RF meter with a diode one
> direction, then the other, you should be able to _safely_ measure any
> difference in magnitude between the positive and negative portions of
> the average coil-base current."
> Think the resistance of the heater in the TC ammeter will
> be so low that the diodes will have no effect.
> Ed Phillips
Ed,
Could be! A small non-inductive resistor in series with the meter, and
then shunting the resistor and meter with the diode may work better if
this is the case. Since we're dealing with relatively high peak current
pulses of several amps or more, a 5-10 ohm 2W carbon or film resistor
would probably do the trick.
Another, perhaps even better, option would be a diode in series with the
meter, but reversed in direction from the shunting diode. In either
case, the whole assembly could then be reverse-connected to measure
current going the other direction. The key is to safely "steer" the base
current while attempting to measure +/- components. Attempting to block
the current flow in either direction will be very difficult, and even if
successful would severely perturb the behavior of the resonator being
measured.
meter
-------/\/\/\/---O------
| |
-------|<-------
meter
------->|----O--------
| |
-------|<-------
BTW, I haven't run across one of these meters at Hamfests yet but I'll
_sure_ be lookin' for one next time!
Safe coilin' to ya, Ed!
-- Bert --