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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