[Elecraft] K2/100 - Power investigation

[Don Wilhelm]

David,

The diode in the DL1 recitfies the RF and you read the DMM in DC volts.
The DL1 uses a peak reading detector across half the load, so the DMM 
will read 1/2 of the zero to peak RF voltage.  At low power levels (less 
than 1 or 2 watts), you should add the diode drop to the indicated 
voltage before calculation of the power, but at higher power levels the 
diode drop is not significant.

BTW: The power formula in the DL1 manual has a small error that shows up 
when calculatiing low powers.  The proper formula can be simplified to P 
= 2x (Vdmm + 0.15)^2/50  - that is: add 0.15 to the DMM reading, square 
it and divide by 25 - the 0.15 term is an assumption for the diode drop, 
those who would like more precision can measure their particular diode 
forward voltage drop.

73,
Don W3FPR

David Wilburn wrote:
> With the DL1, when you do the calculation to get the power level, what 
> do you measure with?  V-AC or V-DC?
>