[Elecraft] Feature wanted for W2 wattmeter
Phil & Debbie Salas
dpsalas at tx.rr.com
Mon Jan 12 19:46:16 EST 2015
"I would like the W2 wattmeter to be able to display "delivered" power,
that is, forward power minus reflected power. This would give a more
accurate indication of power going to an antenna when the SWR is not
1:1. For example, if the SWR on the line is about 2.5 and forward power
indicates 1.2 kW, there is about 200 watts reflected power. In that case
only about 1 kW (less line losses, of course) is being delivered to the
load. It is misleading to look at just forward power."
Actually, "delivered power" is pretty much what you are measuring.
Remember that reflected power is re-reflected by the source and adds
back into the forward power. So in your example, you are transmitting
1200 watts, having 200 watts reflected, then the 200 watts is
re-reflected by the source giving you the 1200 watts. Of course, there
will be transmission line SWR-related losses.
Phil - AD5X
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