A pair of 4CX250s will easily deliver 800W output on six meters, what's so
unique about that? The 3200 volt part is pretty scary, though, since these
are 2000v tubes. My 40+ year-old Johnson Thunderbolt 6n2 ran 2200v on the
plates of a pair of 4CX250Bs and delivered 1kw CW output power indefinitely,
without exceeding the dissipation rating of the tubes. My current homebrew
dual 4CX250B amp on two meters also puts out 1kW CW if run Class C, and 1kW
PEP Class AB1 with 2300v Ep, 350V Eg2 and 10W drive power. In Class C, it
runs ~70% efficiency. -WB2WIK/6
"Nobody needs more than 640k!" -Bill Gates, 1982
> -----Original Message-----
> From: George [SMTP:gclute@comcast.net]
> Sent: Tuesday, October 12, 2004 2:16 PM
> To: Chris Pedder; amps@contesting.com
> Subject: [BULK] - RE: [Amps] Looking for a design for a single
> 4cx250b tube on50 Mhz-six meters.
>
> In about 1965 I ran a pair of 4CX250R's at 3200 VDC and proved to a friend
> of mine that they would put out 750 to 800 watts on 6 meters. They got
> hot
> on long transmissions ..,in fact, the plate leads unsoldered and I had to
> clamp them. This was the time you could buy these rugged ceramics for
> 1.00
> each in the L.A., CA military surplus market. Didn't care if they croaked,
> as they were cheap.
>
> Regards,
> George W7LFD...ex W6BFJ
>
> -----Original Message-----
> From: amps-bounces@contesting.com [mailto:amps-bounces@contesting.com]On
> Behalf Of Chris Pedder
> Sent: Tuesday, October 12, 2004 1:14 PM
> To: amps@contesting.com
> Subject: Re: [Amps] Looking for a design for a single 4cx250b tube on50
> Mhz-six meters.
>
> At 18:51 12/10/2004, you wrote:
> > The manual claims that a single 4CX250B will produce 600 watts peak
> > output. It has unregulated bias supplies as well.
> >I wonder if that is figuring peak voltage squared divided by resistance
> >rather than PEP value.
> >
> >73
> >Bill wa4lav
>
> I use, though not very often these days, a pair of 4CX250Bs in AB1 passive
> grid. On 80-10m they are good for about 550 watts pep out with reasonable
> linearity. 35 years ago there were cheap pulls available here, which made
> them an attractive proposition, especially with out power limit.
>
> Chris
>
>
> _______________________________________________
> Amps mailing list
> Amps@contesting.com
> http://lists.contesting.com/mailman/listinfo/amps
>
> _______________________________________________
> Amps mailing list
> Amps@contesting.com
> http://lists.contesting.com/mailman/listinfo/amps
_______________________________________________
Amps mailing list
Amps@contesting.com
http://lists.contesting.com/mailman/listinfo/amps
|