Why not consider to use 2 x 4CX350 tubes ? With the same setup and
construction effort it´s no problem to get an easy kW out.
73 Win DK9IP/KH7CD
> --- Ursprüngliche Nachricht ---
> Von: Steve Katz <stevek@jmr.com>
> An: "'Dr. David Kirkby'" <david.kirkby@onetel.net>, amps@contesting.com
> Betreff: Re: [Amps] [Moon-net] 4CX250B in P-P 2m?
> Datum: Fri, 31 Mar 2006 09:56:04 -0800
>
> A pair of 4CX250Bs can actually run a pretty clean 1 kW PEP output power.
> Mine does. I operate it at 2.4kV, 640mA peak and it runs 1 kW PEP (CW or
> voice) output power at 144 MHz. The 2.4 kV is slightly higher than
> recommended, but I've done this for so many years it just became the norm.
> My Eg2 is ~350V regulated by gas tubes and derived from the Ep supply. I
> use *lots* of air (100 cfm blower, 4" squirrel cage 3300 rpm, standard
> Eimac
> air system sockets and chimneys). I cannot imagine how it would be
> possible
> to achieve any more output than this from a pair of 250Bs without blowing
> them out of their sockets...mine runs about 1500W PEP *input* power, for 1
> kW PEP output power and draws just 1-2 mA peak Ig to achieve that. I can
> switch it to Class C (-90V Eg1 and +250V Eg2) and run 1 kW key-down with
> less plate dissipation and 20mA grid current. The circuit I use is from a
> mid-1960s ARRL Handbook...-WB2WIK/6
>
> -----Original Message-----
> From: Dr. David Kirkby [mailto:david.kirkby@onetel.net]
> Sent: Friday, March 31, 2006 9:52 AM
> To: amps@contesting.com
> Subject: Re: [Amps] [Moon-net] 4CX250B in P-P 2m?
>
>
> SM6CKU wrote:
> > Hello guys
> > Anyone knowing about a 2m kW amplifier in push-pull with 2x4CX250B?
> > A friend of mine is asking....
> > 73 de Ben
> > _______________________________________________
> > Moon-Net posting and subscription instructions are at
> http://www.nlsa.com/nets/moon-net-help.html
> >
> >
>
> Yes, I know it would be *seriously* over-run. The maximum anode voltage is
> 2
> kV
> and the maximum anode current per tube is 250 mW. So a pair of tubes
> should
> take
> no more than 1 kW of input power.
>
> So needless to say, even if the 2 kW is input rather than output, it is at
> least
> 2x over the tubes specs.
>
> Or perhaps your fiend has found a way of getting 200% efficiency and so
> getting
> 2 kW out with only 1 kW in.
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