Edward Knobloch wrote:
Kevin Dooks wrote:

Sorry, I should have given more info. This home-brew CA
( Canoe Anchor ) covers 40 thru 10M, CW and phone and runs 400 ish
volts on the plate. There are space limitations, height including
envelope and base con't exceed 3 inches max and envelope diameter
can't exceed 1.65 inches due to cabinet restrictions.

If you can't submount the octal socket, even a 5881 won't fit.
Have you considered a pair of 5763 9 pin miniature
transmitting tubes in the final? Each has 12W max plate dissipation,
so a pair would be rated for the same power as a 6L6.
They are small, so not as forgiving of an overload, though.

On 160M, you should be able to get more power out of a 6L6 than a single
5763, but by the time you get up to 20M, the 5763 will be putting out a good
bit more than the 6L6. The shunt capacitance on the 6L6 kills you.

An 8121 tube would fit easily, but it requires a 12V heater,
and the sockets can be expensive. It's finned for a transverse
blower, but at 400V class C, it might not need a blower.
I've bought 8121's on ebay for around $10, a bargain
compared to the pricey 8122, which is the same tube
with a bigger plate dissipation rating (and which requires
through-the-socket cooling).

The 8121 is a really cool gadget, and ten bucks is hard to beat. It is
surprisingly rugged, and if you only want to run HF you can make your own
socket.

If you are willing to pressurize the chassis, a 4X150A
or 4CX250B would fit fine, but your blower might be as large
as the rest of the rig.

Last time I used a 6L6 as a final, I had to submerge the whole chassis in
transformer oil to cool it down. I was getting less than 2W on 10M with
the plates glowing bright red. That was... well... a long time ago....
it seemed like a good idea at the time... and it worked great on 80M!
--scott
--
"C'est un Nagra. C'est suisse, et tres, tres precis."