R: [AMPS] Watt meters and PEP

[Ian White, G3SEK]

measures wrote:
>>>With a 50-ohm load, 387.3v-peak indicates 1500w PEP on the wattmeters the 
>>>FCC uses. 
>>
>>Yes, obviously. There is nothing wrong with that "v-pk" calculation.
>>
>>What I cannot believe is that the FCC make any use of the quantity that
>>you call "w-pk".
>>
>They don't call it that, 

More to the point, they don't mention, consider or use your "w-pk" at
all.

>but this is essentially how one calibrates such 
>a meter.  When one measures 387.3v-pk across a 50-ohm load with an 
>NBS-traceable oscilloscope and multiplier-probe, the "PEP" meter is adj. 
>to read 1500w.  
>
It's one way to calibrate a power meter, but not a good one.

Guess how oscilloscopes are calibrated at RF? By measuring the voltage
across a line connected to a calibrated power meter! In other words, you
improve the error budget by calibrating one power meter directly from
another.


73 from Ian G3SEK          Editor, 'The VHF/UHF DX Book'
                          'In Practice' columnist for RadCom (RSGB)
                           http://www.ifwtech.demon.co.uk/g3sek

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