[Amps] 1 tube or two ??

[Harold Mandel]

Aside from growing technology where a single, high-efficiency
ceramic final tube will provide the horsepower, why were so many
commercial broadcast amplifiers manufactured with dual 4-1000A's?

Why do we see popular designs where two 4-1000A PA tubes are
modulated by two 4-1000A's in push-pull?

Why did Alpha even consider adding the second 8877 to the 
77 series? 

Why do Alpha, QRO, Drake, Ameritron, Commander-1, Heathkit,
Ten-Tec, Yaesu and other amplifiers come with two tubes?

Is not the total anode dissipation of two 4-1000A Tetrodes
two thousand watts? 

Plotting an amplifier with one tube capable of 1KW
anode dissipation, let's say a 4-1000A with 6KV @ 1.0A
anode horsepower, versus a two-tube architecture with
a corresponding 6KV @ 2A supply should achieve
some net output power results, yes?

If it's to be 4-1000A's, let's keep them Tetrodes with
corresponding Grid-Driven input and Screen supplies
to avoid the pitfalls of G-G inefficiencies.

Lastly, if there were no practical advantage to the design,
why would anyone have ever bothered?

Hal

   [snip]
  Two tubes will be very close to 50 ohms input impedance.  They will 
also lower the output impedance easing the Pi-Net requirements.
 A lot depends on how much Plate V you're running.
  [snip]