Watt Meter

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).


Viv Watts (UK)