>
>The generated power is the drawn energy multiplied by the amplifier
>efficiency factor, the delivered power
>is instead the energy effectively transfered to the load.
>
>In a mismatched condition, expecially were readings are done with indirect
>instruments like power meters that read a voltage at a stated impedance
>(which is not if SWR is high), the effective tranfered power is not so
>easily determinable. The algebrical sum of direct and reflected voltage,
>roughly correct as a relative reading and to determine VSWR, could be wrong
>in the read power absolute numbers.
>
>If I were an officer to check the used power in your station and rules are
>relative to the antenna feed point (I don't think so), or I bring the meter
>to the antenna feed point (but looks quite impractical), or I will ask you
>to tune your amp into a dummy load without changing the drive power.
? This makes sense, Maurizio. Whenever SWR is present, wattmeter
reading (and SWR reading) vary according to where the instrument is
placed along the mismatched transmission line. This being the case, the
50 +/- J0 ohm dummy load is undoubtedly the only way to make good
measurements. // . . For yours truly, one of the more delightsome
amusements in amateur radio lore is the insistance by some "experts" that
wattmeters can give accurate readings when SWR is present.
cheers.
- Rich..., 805.386.3734, www.vcnet.com/measures.
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