6EM7

[Paul Barker]

On the power section I tested 16 6EM7 all nos GE boxed, clearly never used.

At a spot position of 150v B+ -15 v grid, the data sheet expects current of 82mA

I have thrown out the dud which is 2mA from the figures so sample is 15.

The figures are 80,85,56,67,68,50,44,31,69,50,56,54,56,48,59

Mean is 58.2 mA
Standard deviation 13.88
Variance (s squared) 192.6

I class it as diabolical by any standard.

I have always known and often stated that my 6em7's don't perform to the data sheet, but looks worse than I realise.

Link to Distribution Curve

[Paul Barker]

That would be a miserable enough situation if like me you were the person who bought these valves in good faith.

But you would have to look at the VA section to build a complete picture.

This was tested at 300v -2 v and by the chart should result in 5.2 mA

This time all 16 gave a result.

Results

3,3,4.8,3.6,5.5,4,4,4.8,3,3,6,4.4,4.4,2.5,3.5,4

Mean 3.97
s 0.983






But unfortunately there is no relationship between the sides, a good 123 does not guarantee a good 456.
Link to the original

[pre65]

Does this sound right ?

"The 6EM7 is a unique old TV tube with an input section similar to
a 6SL7 and an output section similar to a 2A3."

[Paul Barker]

Does this sound right ?

"The 6EM7 is a unique old TV tube with an input section similar to
a 6SL7 and an output section similar to a 2A3."

Eric Barbour?

[jack]

Does this sound right ?

"The 6EM7 is a unique old TV tube with an input section similar to
a 6SL7 and an output section similar to a 2A3."

Eric Barbour?

Tom McNally