-------------- Original message --------------
From: "Edward Foltyn" <email@example.com>
> Ok folks, I'm jumping in here to ask some questions, some of which have
> probably been asked before. I want to build my first amp and over the last
> couiple of years have accumulated much of what I need for in a 4-100A amp (2
> tubes, socket, chimney, transformer from a Johnson Desk KW [capable of
> of 8kv], vacuum variable, etc).
> However, everytime I read this reflector and others, I find that if I run in
> G-G, I'll need more than 100w to get in the 1300-1500w output range and if I
> driven grid, I'll spend a lot of time trying to make everything work.
> My question for the group is to get some ideas on whether or not I should
> proceed with this project, or cut my losses(??) and try to get somethinga bit
> more straight forward.
> Thanks for the advice.
> Ed KQ1R
Whether you should proceed ? By all means ! Though glass tubes in general and
the 4-1000A in particular can be considered a novelty at this point in time
this is exactly the type of tube you want to use for your first amplifier
project. If something goes wrong like a grid to filament short that can't be
cleared or you lose a base or plate seal then you take the tube chuck it in the
trash and start over again. Would you prefer to start with an 8877 get the amp
built, apply power to it the first time, key the relay only to hear the amp
hiss and see the Plate and Grid peg as the amp breaks into parasitic
oscillation ? An event like that can fry the grid faster than you can bat an
eye. At that point the best you can do is send the tube to Rich, AG6K, to be
autopsied and hope the photos make his web page. Even building an amp in a cook
book fashion from schematic and write up can lead to numerous unforseen
problems. What I discern from your post is you should guard against being o
verly ambitious. Don't allow yourself to be trapped into thinking you're going
to get full legal output on all bands with a perfect stable amp from the moment
you first power up. Lower your sights and enjoy the ride. But remember one
thing above all else.
YOU DON' T GET SECOND CHANCES WITH THE VOLTAGES PRESENT IN RF POWER AMPS ! YOU
CAN NEVER SHOW THEM TOO MUCH RESPECT. AND NEVER WORK ON AN AMP WHEN YOUR TIRED
OR FATIGUED !
Bob W6AH ex-K1TA
Amps mailing list