Amp Failure, Efficiency

[Wilson Lamb]

It's heat that stresses the transistors, not efficiency.
The numbers show more dissipation with increasing power level.
WL
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[ANDY DURBIN]

"It's heat that stresses the transistors, not efficiency. The numbers show more dissipation with increasing power level."

Which number show that?  My test data for the KPA500 are very clear.  Peak PA dissipation for any given load is at about half power output.  

Andy, k3wyc

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[Roger D Johnson]

With a switchmode power supply, it would seem to be simple
to provide one or more lower voltage outputs to keep efficiency
up at lower powers (maintain same load Z).

73, Roger

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[ANDY DURBIN]

I had one off-line request for my test data so I'll share a link:

https://www.dropbox.com/s/uf258k1nw8o7xw3/Evaluation%20KPA500%20PA%20Dissipation%20rev%20ad4.pdf?dl=0

I have previously shared other links to reports that are based on the same raw data set.

Please note that the plots in this report contain no data for efficiency but efficiency can be derived from the plotted data.

Efficiency is the ratio of RF output to PA DC input power.   You can derive DC input power from the plotted data by adding RF output to PA dissipation.  In the raw data set I have PA voltage, PA current, and RF output.  I calculate PA DC input power then subtract RF output to give PA dissipation.

This is a draft report and may contain errors.  Comments on test method or results are welcome.  My QRZ address is valid.


Andy, k3wyc




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