[Elecraft] HF amp kits

[Dave G3VGR]

  A pair of tetrodes or pentodes, grid driven in AB1 need little drive, 
so the 12 watts from a K2 may  be sufficient for driving something like 
a 4CX800.  You may need switched tuned inputs instead of passive grid to 
drive it with 12W. I think most amplifiers on the market are class AB2 
(usually grounded grid), which need plenty of drive. The drawback in 
using tetrodes or pentodes in AB1 is the requirement of a regulated high 
voltage for the screen grids and the amplifier would  probably need 
neutralizing also, especially if not operating in passive grid.  Most 
available tetrodes are ceramic types, so a blower would be necessary too
As you intend only running CW, it may be worthwhile investigating class 
E amplifiers which would present you with more modern obstacles to 
overcome :-)
73, Dave G3VGR
K2 #4783

Chris Kantarjiev wrote:
> [warning thread drift]
> 
> The Linear Amp kits seem to need a fair amount of drive. I've been
> idly thinking about a linear that would allow me to drive it with
> my barefoot K2 and get 600-800 watts out for CW.
> 
> I've been told that such things were "common" in the 70s. One description
> I was given is
> 
>  two stages, with a pair of 6CL6 pentodes in class A passive grids,
>  driving a pair of surplus 4CX250Bs in AB1,a very common design.
>  0.1W in gives 650W out.
> 
> which sort of means something to me, but will certainly start many
> evenings of study.
> 
> If this was "common", it seems that there should be articles. I haven't
> had much luck finding one (there's an article from 1959 that uses
> a single 4CX250B). So, how about it, you guys who were there then? :-)
> 
> 73 de chris K6DBG
> _______________________________________________
> Elecraft mailing list
> Post to: Elecraft at mailman.qth.net
> You must be a subscriber to post to the list.
> Subscriber Info (Addr. Change, sub, unsub etc.):
>  http://mailman.qth.net/mailman/listinfo/elecraft    
> 
> Help: http://mailman.qth.net/subscribers.htm
> Elecraft web page: http://www.elecraft.com
>