[Lowfer] reERP calculation

[John Andrews]

Alan's point is well taken. The transformer + diode metering setups with 
high impedance loads that allow their filter caps to charge to peak are 
very much peak-reading setups. Calibration assumes a sinusoidal current 
with the usual 0.707 conversion from peak to RMS. Should the waveform 
not be sinusoidal, then that calibration does not apply. For typical 
LF/MF single-tone signals with the usual high-Q antennas, they should be 
sufficient.

John, W1TAG

On 1/25/2015 4:36 PM, Alan Melia wrote:
> Hi Neil I am not sure about your assertion the rf ammeters read average
> power. Surely the thermocouple variety (yes I have a box of then from the
> 1950s ::-))  ) use heating effect so measures rms directly.
>
> The ferrite transformer type with a low  impedance moving coil meter
> measures mean and needs a 1.11 calibration factor applying . However if a
> high impedance detector, DMM, current probe into 'scope or panel meter, is
> used then this measures peak current which requires multiplication by 0.71.
> I think. Perhaps John could comment as his circuit is recommended :-))
>
> Dave Powis kit (see http://g4hup.com/RFC/RFC.htm) is calibraated and
> chacked against an HP power meter so reads rms.
>
> (just to show I am still lurking in the background )
> Alan
> G3NYK