[Amps] 200-ohm tank and "un-un" in HF amp design?

[Jim Barber]

Good point.

If I lower the swing to 3800 and raise the current to 658mA to keep the 
same dissipation, the guesstimated plate load impedance drops to 3610 
ohms. Lowering the Q to 10 then puts the loading cap to 923pF @ 1.8mHz, 
which works.

(I'm also using 3uH of "lead" inductance left of the PI network to help 
mitigate the capacitance issues at higher frequencies. That raises the 
load side capacitance requirement slightly on 160M, in case someone 
tries to work these numbers)

Thanks,
Jim N7CXI

On 10/21/2013 4:34 AM, Peter Voelpel wrote:
> I don´t believe that the anode voltage drops to zero volts at 625mA anode
> current.
> 4KV voltage swing in your calculation is probably too high.
>
> 73
> Peter
>
> -----Original Message-----
> From: Amps [mailto:amps-bounces at contesting.com] On Behalf Of Jim Barber
>
> Just to clarify, I used 1.6 for "K", which in Ian's spreadsheet is in
> the middle of the range for AB:
>
> Single 8877
> 4KV
> 625mA
> 60% efficiency
> "K" factor of 1.6
>    = 4000 ohms plate load impedance.
>
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