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Re: [Amps] Plate Impedance, ARRL

To: craxd1@verizon.net, amps@contesting.com
Subject: Re: [Amps] Plate Impedance, ARRL
From: Peter Chadwick <g3rzp@g3rzp.wanadoo.co.uk>
Reply-to: g3rzp@g3rzp.wanadoo.co.uk
Date: Wed, 12 Apr 2006 18:53:44 +0200 (CEST)
List-post: <mailto:amps@contesting.com>
Will said:
>Everything I've read says AB is around 60% efficient, not less.<
I think you'll find that's the theoretical tube efficiency, and the real world 
has to take into account tank circuit transfer efficiency, too.
>From memory, the old Mullard data sheets provided measured values with tank 
>circuit efficiencies stated as around 90%. I've always worked on a rule of 
>thumb of 50% efficiency, and haven't been let down that much, especially when 
>you consider the measurement uncertainties involved.
And if your tank circuit when you've tuned and loaded for optimum ends up with 
a working Q of 15 instead of 12, I doubt if any of us has equipment with enough 
resolution to tell the difference, let alone make an absolute measurement.
I guess we can get too hung up calculating (or worse, simulating) for the last 
fraction of a dB that can't be achieved in practice. Makes you wonder how they 
ever got radio to work in the first place!
73
Peter G3RZP
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