I remember seeing something like that around the '60s, in QST I believe.
It was built into a suitcase by a guy who traveled a lot, to be used in
hotel rooms. (Imagine the RFI problems!) I don't think that particular
one was using 807s, though -- I believe it had some later type of sweep
tube that wasn't as tall.

The 807 was, incidentally, used as a sweep tube. In the middle '60s I
worked on heavy ground radar (mostly '50s vintage), and the 12 inch PPI
(round) radar scopes used push-pull 807s for the deflection. I once had
a huge box full of 'em too, but they had to go when we moved from Alaska
to the lower 48. They're probably still up there somewhere. . .

Roy Lewallen, W7EL

Philip de Cadenet wrote:
Ken,

I recall one amp used a voltage quadrupler to get 600 volts from
the 120v ac line and had 10 tubes with the heaters wired in series.
One tube was a driver, and 9 were grounded grid finals.
(A bit of a shock hazzard perhaps.)


I've seen something similar here in the UK 20+ years back and remember
the amateur who built the thing. I think he was playing around the Kw
level and with no transformers in sight.

We do have a head start on you fellas with 240v @ 50Hz :-)

A 'bit' of a shock hazard is kind of an understatement don't you think.

Speaking of 6146's.... I purchased a dozen of them in near unused
condition from a radio repair shop. How rare or coveted are these
tubes?

The Eternal Squire

wrote:
...nostalgic about the boxes of old 807's they had sitting around waiting

to be used - has anyone built a HF linear using these things - and not
QRP or max 100watts ....


I can't find it right now, but somewhere I have an article from a ham
magazine that used TEN of them (actually 1625's), with their filaments
series'd across the 120-volt mains and their outputs paralleled on one
of the lower ham bands.

I, too, have been saving them and will find the round tuit someday.

--Myron.

"The Eternal Squire" wrote in message
...
Speaking of 6146's.... I purchased a dozen of them in near unused
condition from a radio repair shop. How rare or coveted are these
tubes?

The Eternal Squire

wrote:
...nostalgic about the boxes of old 807's they had sitting around waiting

to be used - has anyone built a HF linear using these things - and not
QRP or max 100watts ....


I can't find it right now, but somewhere I have an article from a ham
magazine that used TEN of them (actually 1625's), with their filaments
series'd across the 120-volt mains and their outputs paralleled on one
of the lower ham bands.

I, too, have been saving them and will find the round tuit someday.

--Myron.


I got 200 pulls, all tested good, for $0.25 each, so far I've used 12.

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