Ignoring diode non-linearity and other spurious imperfections, the output of
a directional coupler is a constant fraction of the forward voltage from the
transmitter. The scale of the meter shall be quadratic. Remember that power
is voltage squared divided by load resistance. This worked fine for my last
project, that was a pcb type directional coupler.
73 de LA6MV
Helge
-----Original Message-----
From: Martin Sole [mailto:msole@loxinfo.co.th]
Sent: 6. oktober 2003 11:40
To: amps@contesting.com
Subject: [Amps] Power meter calibration
Apologies if this is not really amps but lots of wise old owls on here
methinks.
I have built a power meter, to measure the power out of my amplifier,
hopefully that keeps this on track. I have a question concerning
calibration. Ignoring diode non-linearity's and other spurious
imperfections, what sort of law should the meter scale be calibrated
according to. I have the WB6BLD meter scale drawing program for which
the included 200 watt scale uses a linear exponent of 0.55. Having tried
this it just doesn't seem right. What's the formula?
73
Martin, HS0ZED
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