[AMPS] tube compatability

[w8jitom@postoffice.worldnet.att.net]

> From:          Rich Measures <measures@vc.net>Rich,

We've been over this a hundred times.

You wrongly insist you can simply multiply the RMS drive voltage 
against the indicated meter current.

> -  100mA equates to about 2.7w. 

That's nonsense.

We have no idea what the grid dissipation is unless we know the 
driving voltage AND waveshape of the grid current at the particular 
operating point. Since it is under a condition of mistuning, it is 
not in Eimac's data.

Eimac does say (as I-- and others--- have pointed out to Rich several 
times) grid dissipation can be estimated by taking the grid cathode 
PEAK voltage and multiplying it times the indicated grid current.

This calculation is approximately true for most operating conditions, 
as long as we remember the peak voltage is not the voltage under 
normal tuning conditions. As the loading is lightened, the peak 
grid / cathode voltage increases in a grounded grid amp.

Short of a direct measurement, a more accurate method is available 
using software supplied by Eimac, or a program called "triode". Using 
the software will convince anyone (except Rich) tubes can be 
easily damaged by improper tuning.

73, Tom W8JI

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