[Amps] PA efficiency

[Jeff Blaine]

David,

In the case of the GG, do you not need to deduct the drive power from the Po?  Otherwise, the efficiency is overstated and the Pd is 
understated.  I could be wrong?

73, Jeff ACØC
www.ac0c.com

-----Original Message----- 
From: Dr. David Kirkby
Sent: Tuesday, May 17, 2011 11:36 PM
To: amps at contesting.com
Subject: Re: [Amps] PA efficiency

On 05/18/11 05:27 AM, Carey Lockhart, KC5GTT wrote:
> hello all,
>
> what is the proper formula to get the PA efficiency of a amplifier?
>
> Carey

1) Calculate the input power = V * I

where V is anode/collector/drain voltage (depending on whether its tube or
semiconductor

I is the anode/collector/drain current (depending on whether it's tube or
semiconductor)

2) Measure the output power P.

3) Efficiency (in percentage) = 100*P/(V*I)


Note, few power meters are going to be accurate to better than +/- 10%
(including the Bird, despite its spec of 5% of FSD), so don't expect an accurate
result unless you use a precision power meter with a calibrated coupler or
attenuator.

Dave
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