# Roughly calculating efficiency of transmitter.

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#### neazoi

Hi again, how can I calculate the efficiency of a transmitter?

I would like to know if my thinking is correct by a simple example:

Assumming that a transmitter outputs 4W of RF power at 50R and consumes 290mA at 22V.
Then for 4W output, the transmitter consumes P= 22v * 0.290A = 6.38W

so, at 6.38W of consumtion, 4W is outputed.
bringing that to % percentage, it is (100*4)/6.88 = 62.69

This means that the transmitter is 62.69% efficient.

Am I right?

Yes, you are right. If the 4W is the peak power, then the number is peak efficiency. If 4W is average power, then the number you have got is average efficiency.

If you are characterizing Power Amplifier, you may need to quote its Power Added Efficiency (PAE).

62.7 % Efficiency, that is very high unless its a class C. From memory, max eff of class B = 78%, allowing a PI tank circuit with a loss of 10 % ( Qunloaded = 100, Q loaded = 10) gives 71%, so you reasonabley close to the theoretical maximum.
Frank

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