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Re: Watt Meter





Tesla List wrote:
> 
> Original Poster: "Vivian Watts" <V.C.Watts-at-btinternet-dot-com>
> 
> Hi All,
>     Being interested in the difference between the VA rating and the rms.
> power taken by my coil I managed to purchase a Watt meter at a local Amateur
> Radio Rally.  It is rated for A.C and D.C. but I'm not sure it is suitable
> for giving the true power on reactive loads and was wondering if anyone
> knew.  It is a Weston Model 310 made in Newark NJ USA dated 1941.  It is
> referred to as a electrodynamometer wattmeter.  Frequency range to 133Hz.
> Cost 10 ($15).
> 

As that guy at the soccer game says, SCORRRRRRRRE!  You got a beaut
and at a tremendous price.  Until fancy electronics came along, the
electrodynamic wattmeter was the lab standard.  It will still handle
high crest factor power better than most electronic wattmeters.  It
will work equally well with AC and DC.  The only extra step with DC
is to take a reading, reverse the potential leads, take another
reading and then average the two.  This cancels out the residual
magnetism that may remain in the meter parts after a DC measurement.

John
-- 
John De Armond
johngdSPAMNOT-at-bellsouth-dot-net
Neon John's Custom Neon
Cleveland, TN
"Bendin' Glass 'n Passin' Gas"