Re: Magnetic quenching.

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

Original poster: "Jim Lux" <jimlux-at-earthlink-dot-net> 


----- Phillips <evp-at-pacbell-dot-net>
 >
 > "With an AC voltmeter, a series resistor and a series capacitor or
 > inductor,
 > you can measure true power, apparent power, vars, watts, power factor
 >
 > OK except for the numbers. Try ~10 ohms instead of 0.1 ohm.  I thought
 > the "three voltmeter method" was long forgotten, and never heard of its
 > use for RF.  Actually, all it takes is a resistor and the load to be
 > measured - the reactance isn't needed. I worked out the arithmetic and
 > posted it here a while back.  The arithmetic is simple, and a graphical
 > construction works fine too.

Just realized that one way to do it with just a resistor would be if you had
two different resistors (one of which could be zero ohms) and made current
and voltage measurements with the resistor in series and not.

However, for line frequency kinds of applications, and given the cheapness
of devices like the Kill-A-Watt, or inexpensive current transformers, etc.
and  a PC sound card, that's probably a preferred approach.

The sound card would give you bandwidth to 20 kHz or so.. that's lots o'
harmonics