J M Noeding wrote in message . ..
On Thu, 16 Sep 2004 07:40:25 -0700, Bill Turner
wrote:



The problem with 807's is that having only a 25 watt plate dissipation
rating and running a pair in a linear with about 66% efficiency, you're
only going to get out about 100 watts. Today's generic transceiver
already puts out that much, and if you're looking for an HF "brick" for
a QRP rig, solid state is a better way to go.

On the other hand, a nostalgia-driven project could be lots of fun.

Back in the olden days they were a useful tube, but not so much anymore.
Too bad.

the more important limiting parameter for application as ssb linear
amplifier is max cathode current.

It could be mentioned that 4-65 has the same max PEP input as 4-125
because the cathodes are the same

-jm
---
J. M. Noeding, LA8AK, N-4623 Kristiansand
http://home.online.no/~la8ak/c.htm



All points noted - I am aware of the limitations of the things,
but.....

4 of them in // should be capable of 200 watts output - yep, not QRO
but a 3db improvemnet over the 100 watts of the typical modern HF
radio. The G2DAF circuit looks interesting - simple, robust, forgiving
- and VK4YE's work on matching input impedance to a modern 50R HF
radio sems to solve the drive mismatch impedance problem.

So, will stuff around and experiment - it should be a good junkbox
project - as a monobander would be relatively simple to construct -
dirt cheap, a learning experience, and as numerous people have noted,
there are THOUSANDS of 807's in junk boxes all round the world, just
eagerly waiting to be used again.......

Thanks to all who posted,

Andrew VK3BFA