[Amps] Emission numbers

[Bill Turner]

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On Tue, 12 Jan 2016 20:33:25 -0500, KA9P wrote:

> 
>Can anyone explain what a good/bad emission number is on a used  
>transmitting tube like an 8877?  Or just point me to an explanation?

REPLY:

"Bad" is mostly in the eye of the beholder. A "good" tube should match
the plate current curves shown in the data sheet. That is, for a given
plate voltage and grid bias, the plate current should be xxx mA as
shown on the graph, especially at the higher end of the graph. A tube
that has low emission will be lower than that, but how much lower can
vary a lot. If it is just one or two percent lower, for all practical
purposes, I would call it a good tube. Below that, the tube is
probably still useful but it depends mostly on how hard you want to
drive it.  

In other words, there is no strict definition of a "bad" tube. It all
depends. 

73, Bill W6WRT