>In response to various comments made on my original posting.
>
>I think that some hams misunderstand the basic principles of of rf
>amplifiers!
>
>The load impedance of a tube is defined by the anode voltage and the output
>power and is calculated using the formula: (assuming that 80% of the dc
>supply is available to develop the rf voltage swing, which is pretty close
>to what happens in practice)
>
>
>RL = (0.57 x Va2)
> -------------------
> Po
>
>Taking an amplifier with, say, 2kV anode supply and an ouput power of 100W
>gives RL as 22800 ohms.
>
>Using the same anode voltage but now running 1kW output the tube load line
>(RL) is 2758 ohms.
>
>Obviously the Pi tank network will not be able to provide matching at both
>of these load impedances without some drastic changes to the L & C's.
>
>This is an over simplified example .......
? This presumes that the anode's voltage swing at 100w output in the
1000w amplifier is approx. 80% of the supply potential, which is
undoubtedly not the case. It seems to me that RL at any power level is
closely related to dV/dI
- later, John
Rich...
R. L. Measures, 805-386-3734, AG6K, www.vcnet.com/measures
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