>I'd patent that feedline. Take out the wattmeter and put in a load that
>will draw out that 1700W indicated by the wattmeter with 1500W steady-state
>in and you've got a perpetual motion machine.
NOT A CHANCE--see below, Robert.
>
>Better yet, short the other end of the coax and you should be able to pull
>out 3000W.
>
>If you grant that the wattmeter isn't really reading watts, then how can
>you accept any readings that it produces?
Robert,
Now, please try to understand the following, ok?
Watt meters do read real power, and the 1700 watt reading is real;
it is the sum of 1500 watts out of the transmitter plus 200 watts
reflected from the tuner. ok, simple arithmetic. 1700 watts IS
travelling up the line towards the antenna!!
But, at most, only 1500 watts ever exits the line into the antenna
input terminals, because 200 watts are continuing to be reflected
at those terminals, caused by impedance mismatch between
the line characteristic impedance and the antenna impedance!
So, when the meter is turned around, it will read a real 200 watts
travelling back down the line towards the tuner, where, because
of what tuners do, it is re-reflected back up the line as forward
power, and adds to the fresh 1500 watts out of the transmitter
to produce a total of 1700 real forward watts. And, yes, even
with the high vswr on the line, a REAL 1500 watts of coherent
RF power is radiated by the antenna! And no, the same 200
watts of reflected power is not circulating in the line; it is a
different 200 watts every instant.
The transmitter never puts out more than 1500, the antenna can
never see more than 1500, in fact a little less because of
I-squared-R resistive losses in the attenuation of the line.
No perpetual motion machine, no opportunity to patent the
line, just the laws of Mother Nature doing what they always
do: obeying the apparent laws of physics.
73, Jim, KH7M
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