I just ran across the following in the on-line manual for the VFD wattmeter:
" If your transmitter has an internal tuner, you might want to turn it off.
The internal tuner will cause a 50 ohm impedance to be presented
to the finals of your transmitter, thereby changing the characteristic
impedance present at the antenna jack on the transmitter. This will affect
the accuracy of the VFD (just as it would any other measuring device)."
I'm well aware of the effect on wattmeter accuracy of operating into a load
that is other than 50 ohms, but this is the first time that I've heard that
the source must also be 50 ohms. This would seem to imply that when I tune
up my linear through my wattmeter to match other than a 1:1 SWR, I am
introducing an additional source of inaccuracy because the impedance at the
output of the linear (as seen by the wattmeter) will be other than 50 ohms.
Correct?
73, Pete Smith N4ZR
n4zr@contesting.com
Sometimes a tower is just a tower
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