Hi Bill,
25 dB is a lot to expect from a single stage but...
Perhaps, you should consider the 4CX350FJ. It only takes 20V peak RF drive.
A swamped grid input, with a suitable parallel L to cancel the input C on the
higher bands, would work fine with 5 watts drive. No neutralization required.
Four paralleled could be pushed to the legal limit; amateur style. 5 or 6
would be a more reasonable approach.
Or perhaps a two stage amp with a '350 input driving any suitable tube.
Enough extra gain would be available to incorporate serious RF feedback for
superb linearity.
73 & Good morning,
Marv WC6W
http://wc6w.50webs.com/
--- On Wed, 6/24/09, Bill Turner <dezrat1242@yahoo.com> wrote:
> From: Bill Turner <dezrat1242@yahoo.com>
> Subject: [Amps] Amp ideas needed
> To: "Me" <dezrat1242@yahoo.com>
> Date: Wednesday, June 24, 2009, 11:23 AM
> Looking for some ideas on how to best
> design an amp.
>
> In September, Flex Radio is going to offer a Software
> Defined Radio,
> model Flex-1500, for just under $600. It will be a QRP
> version with
> only five watts output.
>
> How would you design an amp for 1500 watt output on 160-10
> meters with
> only five watts drive? Some possibilities:
>
> 1. A grounded-cathode 4CX1000A (or similar) with high
> impedance input
> and Bruene neutralization.
>
> 2 A grounded-grid 8877 (or similar) with a modular
> solid state driver
> such as one from Communication Concepts or similar.
>
> Other suggestions?
>
> 73, Bill W6WRT
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