[Amps] SWR and amplifiers

Paul Christensen w9ac at arrl.net
Wed May 24 23:49:31 EDT 2017


>"The wattmeter shows 1000 watts because the reflected 100 watts is
re-reflected back towards the antenna and adds to the 900 watts from the amp
on the wattmeter. The wattmeter shows 1000 watts (assuming the wattmeter is
a meter such as a Bird)."

It's probably worth noting that the mechanism responsible for this effect is
developed by a phase reversal from the load reflection where the reflected
wave becomes in phase with the voltage and current of the source wave
produced by the amplifier.  As Gary points out, the reflected reading on a
Thruline type of wattmeter must be subtracted from the forward reading to
attain an accurate forward power result.

Paul, W9AC




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