[AMPS] 50MHz Amp Details

[Mike Willis]

> Gentlemen,
>
> I wonder if you may be able to help?
>
> I'm trying to find some details about a 50MHz amplifier, using possibly a
> pair of 4CX250B's. Do you know of construction information of such a
beast?

It is entirely possible. I built one. However, if you age going for a PI-L
type circuit, you really need to ensure the absolute minimum anode
capacitance. I have done away with anode tuning altogether, employing a
tuned L with the shorted turn approach commonly used with 3-500Zs.

I abandoned 4CX250Bs on 6 in favour of the cheaper, simpler, quieter 3-500Z
designs (no screen supply, axial blower). These are well suited to modern
100W 6m multimodes.

A pair of 250Bs is now developed for use on 4m where I have only a few watts
drive. Again, parallel operation, PI with tuned inductance.

Mike

Mike


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