[AMRadio] Legal limit AM amplifier, homebrew

[Rick Poole]

At 06:40 PM 11/12/2011, Bernie Doran wrote:

 >>>>>
>Hi Rick: if you really want full CW power ( 1500W) then your tube selection
>becomes more narrow, unless you are willing to run four in push pull
>parallel.
<<<<<

Good evening, Bernie.

I wouldn't mind doing that.

But... and like I said it has been 40 years so I'm exposing my 
ignorance / forgetfulness here... aren't push-pull amps normally run 
class B?  I guess one can run a push-pull amp in class C but does 
anyone ever do that?

 >>>>>
>If you
>never intend to exceed the so called AM limit a linear is probably the
>easiest, no big mod transformer required and no need to change the voltage.
<<<<<

What is that "so called AM limit" you mention?  Is that the 535 watts 
input I calculated, or something else?

Yes, I suppose if I can get 1500 watts PEP output from a linear 
running AM, it'll sound the same on the other end as 1500 watts class 
C with a high-level modulator, and as you say I'll be burning up in 
the modulator most of my savings by going class C... although I could 
presumably do it with smaller, cheaper tubes by keeping the dissipation down.

Lessee... four 833A's in class B push pull parallel... that's 40 amps 
at 10 volts just for the filaments, and 1200 watts total plate 
dissipation rating (4x300) according to the Svetlana data sheet.  Can 
I safely get 1500 watts PEP AM out of that?  At, say, 60 percent 
efficiency (is that realistic?),  1500 watts PEP out requires 2500 
watts in, 1000 of which is dissipated.  Cutting it kinda close.

Those 833A's are kind of bizarre.  I read somewhere (can't find it 
now) that you don't use them with a socket.  How do you mount those things?

Rick WA1RKT