Jim Thompson wrote:

On Tue, 20 Mar 2007 00:34:10 GMT, Joerg
wrote:


Jim Thompson wrote:


Oh my! Nostalgia!

Stumbled onto this site...

http://tdsl.duncanamps.com/schematics2.php?make=Dynaco

I built the FM3 and the PAS2 when I was a kid ;-)


I built more mean stuff when I was a kid. An amplifier with several big
horizontal flyback tubes in there etc. 900V on the plates, directly
cascaded out of 230V grounded mains, sans transformer because that would
have cost too much...

Actually I still got that amp but a typical 120V circuit is too wimpy
for it.


I built at least six different tube power amplifiers, starting with
6V6, then 6L6, then a variety of 6550, KT88 and similar.


Mine was with PL509 tubes. Those are color TV flyback drivers rated at
30W plate dissipation. But you could push them up to 70-80W dissipation
before the plates went from cherry-red to orange.

Of course having to always watch the plates and make sure they don't go
too far into an orange glow was a hassle. So, I built the gorilla of all
amplifiers with two of these puppies:
http://datasheets.electron-tube.net/...q/QB5-1750.pdf

5kV on the plates. Those tubes can easily pack away 500W of plate
dissipation without a whiff of redness. Each.

--
Regards, Joerg

http://www.analogconsultants.com