On Nov 27, 6:50*pm, Ian Jackson
wrote:
In message
,
JIMMIE writesI have a Homebrewed SWR meter I was thinking of calibrating it to read
power by appling a dial for the *"full scale adjust" potentiometer.
Meter would be initially calibrated against a know accurate wattmeter.
Variable HIgh Power RF source would be an *Amateur band SSB TX
modulated by a single tone audio source. Power varied by adjusting the
level of the tone. Power would be read from the dial pointer. One
thought is to use a difference meter reference for each ham band ....
10M full scale 15M a little less. Any thought s on this method would
be appreciated.

Provided you calibrate it, the meter should be able to 'dual-task' as a
power meter. An RF power meter is really only an SWR meter which is
calibrated accurately in power.

The variation of the SWR meter's sensitivity from band to band depends
on which type of circuit it uses.

If it's the 'old-fashioned' type, which uses a short length of
air-spaced coax with an additional wire inserted as a coupling loop, the
sensitivity increases significantly with increasing frequency.

If it is of the ferrite transformer type, the sensitivity should be
pretty constant on all bands, and that is the best type to use for power
measurements.
--
Ian

Yes Ian it does use a piece of coax for the pickup. It should be a
simple matter to modify it to the ferrite transformer type.

Thanks