[AMPS] Re:

[W8JI@contesting.com (Tom Rauch)]

> >When the FCC measures power, they use a regular peak reading 
> >meter. .....
> 
> ?  wanna guess how such meters are ultimately calibrated?.  

No need to guess. Bird calibrates them on a caloric standard. Not 
a scope in sight.

Now there is nothing wrong with using a scope, assuming you have 
one with the required accuracy and resolution and a good load, but 
it is not a good instrument for use in antenna system to measure 
power. Errors in power readings occur at both the square of the 
voltage reading error as well as proportional to load impedance 
error.

There is absolutely nothing wrong with using a good meter. A few 
people have wrongly assumed a storage system can't respond fast 
enough, but that is certainly not correct. The storage system has 
to track the envelope change rate that follows audio, not the RF 
cycle change rate. A meter with directional coupler also remains 
accurate over reasonable load impedance errors. You simply 
deduct reflected power from forward power.


73, Tom W8JI
w8ji@contesting.com

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