[Elecraft] [K3] 1.0 Milliwatt Calibration

[Jon K Hellan]

Julian, G4ILO wrote:
> I was wondering why my 2m transverter was producing much less output than
> when I set it up, so I thought that perhaps I should do the 1 Milliwatt
> calibration procedure, which I never have done. I don't, unfortunately, have
> an accurate RF voltmeter, but I do have an Elecraft DL1 and a DVM.
> 
> At 1mW requested power I measured 36mV at the DL1 test point, which
> according to the formula (.036 x 1.414) + 0.15)^2 / 50 means I am only
> getting 0.8mW out. Is it OK to use the DL1 and this formula at this power
> level?
>

The formula assumes a constant 150 mV voltage drop across the diode, i.e. that it is conducting during
a half cycle. At the level you are measuring, things are more complicated. So I wouldn't rely
on the formula.

Things you could do:

1. Make an amplifier, and calibrate it.
2. Borrow a scope to make the measurement. You probably have to do this in order to do (1), as well.
3. Make a computer model in spice, and tweak until you get the the measured voltage. Spice wasn't
   around when I was studying circuits, but the DL1 looks simple enough to be a great case for
   learning it.

73
Jon LA4RT