> I've achieved 1kW PEP out with 5W drive from a pair of 4CX250B's, grid
> driven, obviously.
>
> Ep = 2200V
> Eg2 = 350V reg
> Eg1 = -55V reg
> Ip = 650mA
>
> The tubes are not expensive, and are readily available, as are the
> sockets, chimneys, etc. Drawback is these tubes have lots of gain up to
> 500 MHz, so you may need a bandswitched plate choke, and possibly other
> components, to avoid resonances that will make your amp into a nifty QRO
> oscillator; although, I never resorted to such extreme things. I used a
> plate choke having multiple windings on a single form spread over a fairly
> long distance (about 8"), with several ferrite beads at the cold end of
> the choke and three low-value doorknob caps to ground to provide multiple
> bypasses at that point. I think those values were 100pF, 220pF and 470pF.
>
> The other area to watch closely is the screen decoupling. There, I didn't
> use any choke at all, but rather a pair of 220 Ohm 2W carbon resistors,
> ferrite beads over their cold ends, and NPO ceramic bypass caps, and I
> also used the "screen bypass caps built in" type Eimac sockets, which seem
> to be good to at least 440 MHz.
>
> The only puzzling thing is why anyone would want to run a kW from an
> FT817. Could be quite the alligator.
>
> WB2WIK/6
>
> "If everything seems under control, you're just not going fast enough." -
> Mario Andretti
>
> -----Original Message-----
> From: Mike Krzystyniak [SMTP:k9mk@flash.net]
> Sent: Tuesday, July 16, 2002 10:02 PM
> To: amps@contesting.com
> Subject: [Amps] KW Linear for FT-817
>
> I'm researching an amp project for a friend. He wants a legal limit or
> near
> legal limit amp that can be driven from a Yaesu FT-817. It's been 25
> years
> since I rolled and amp so I thought I'd ask the gang here. Does anyone
> have
> a suggestion for a tube or pair of tubes that when driven with 5 watts
> will
> run up to a KW out?
>
> Thanks... Mike K9MK/5
>
>
>
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