[Amps] Bill Orr comment

[Steve Katz]

::Yup.  

-WB2WIK/6

Depends on what Orr means by the statement ... if he means that 
the output (amplifier + feed through power) will be at least 
twice the power dissipated in the tube, he's probably accurate 
at "two times."  If he means that a tube should be capable of 
producing 2.5 times its plate rated plate dissipation (e.g., 
1250 W in a 3-500Z or 3750 W in an 8877), he's mistaken or 
worse. 

For example an 8877 is rated for 1500 watts plate dissipation. 
Even at maximum HV (4KV) and maximum current (1A) - Eimac 
Absolute Maximum ratings - you will not see 3700 W output.  
Eimac's own data sheet shows only about 2KW at 3500V/1A.  

The calculations are similar for the 3CX800 - 2500V/.6A gives 
about 900 Watts out based on the absolute maximum ratings.  Even 
with Eimac's own data showing 800 mA for "short term duty" 1370W 
output is far less than 2X the 800W plate dissipation.  

Absolute Maximum ratings for a single 3-500Z are 4000V/.4A 
or 1600 W in.  With 65% efficiency, the output is barely twice 
the plate dissipation.  Eimac's typical operating conditions - 
3KV/.37A - shows 750W output or only 1.5 times rated plate 
dissipation.  

There may be tubes with lower rated plate dissipation that 
can be driven harder but these three examples say that Orr 
was over reaching with his statement. 

73, 

   ... Joe, W4TV