[Amps] Looking for a design for a single 4cx250b tube on50Mhz-Six Meters

[Steve Thompson]

On Tuesday 12 October 2004 17:29, Karl-Arne Markström wrote:
> I agree, the tuned circuits in this amplifier do look not very optimised...

I usually use a series tuned circuit at the input, with a variable capacitor 
onto the grid to adjust the coupling. That's based on a suggestion I saw that 
the parallel circuit has the risk of a spurious vhf/uhf resonance between the 
grid capacitance and the inductor, which is something to consider when the 
tube has useful gain to 500MHz and beyond. Maybe it's a false premise, but 
I've not had any problems.

Steve