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Author Topic: new "standard" for measuring RF power  (Read 31641 times)
G3RZP
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Posts: 4845




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« Reply #30 on: September 23, 2013, 12:19:05 PM »

Interesting is Agilent Application Note 64-1C, and their measurement uncertainties - which can give an expanded uncertainty of 3.88%.

But for amateur use, what does it matter if it's reading 500 watts when it's really 400 watts? Who really cares?
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W9PMZ
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Posts: 575


WWW

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« Reply #31 on: September 24, 2013, 04:24:00 AM »

From the search on that note,
"7, “Measurement Uncertainty,” in
Application Note Fundamentals of RF
and Microwave Power Measurements,
literature number 5965-6630E. This
SWR value would be in contrast
to the warranted maximum SWR
specifi cation of 1.12 (at ≤ 0 dBm, for 1
GHz) contained in Data Sheet E4416A/
E4417A EPM-P Series Power Meters
and E-Series E9320 Peak and Average
Power Sensor, literature number
5980-1469E. Like the temperaturebanded
calibration factor data,
this value provides a lower overall
measurement uncertainty."

As you can read uncertainity is based on return loss of the sensor and the load.
Get a handy dandy Besser Associates Mismatch Error Limits calculator.
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WB6DGN
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Posts: 619




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« Reply #32 on: September 30, 2013, 08:24:05 PM »

Quote
A Bird meter is only accurate to their standard at or near full scale.

Quote
Note that the Bird 43 and the Coaxial Dynamics 83000-A accuracy (measurement uncertainty) is 5% of FULL SCALE and not 5% of measured powe

And that matters HOW?  Proper measurement technique requires that a range of measurement be selected that results in an indication at 3/4 scale or slightly above.

Tom
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