I'm not overly impressed with the commonly accepted Bird meters in the ham
community. I am looking for something much better, for sure. Guess I should
look into this Collins Bridge 312B-4 or go to calibrated occiliscopes.
Not sure what you mean by this. A calibrated oscilloscope, with a
properly compensated probe, may be able to make a more accurate RF
voltage measurement. If you want an indication of the ratio of forward
and reflected RF power, you will still need to connect the scope to some
type of directional coupler or bridge.
Last time I checked oscilloscope voltage measurement accuracy
specifications, good ones were on the order of +/- 1%. (That was a long
time ago, so maybe they are a lot better these days. But then if you're
thinking of using a used oscilloscope.....) When using that figure to
calculate power, assuming a known impedance, using E squared/R, you are
going to get hardly better than +/- 2% accuracy. If you include
imbalances in the directional coupler forward and reflected coupling
factors, pretty soon you're going to be back down to Bird model 43
wattmeter accuracies.
Anyway, when it comes to checking an antenna system VSWR, super high
accuracy is not needed to determine whether the SWR is low enough, nor
is it needed to adjust a matching device, or the antenna, for minimum
reflected power.
DE N6KB
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