M7 Tube Data

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Paul Barker
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#1 M7 Tube Data

Post by Paul Barker »

I have always wanted data for the M7 valve which I have a pair of.

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The only internet search reveals nada.

M7

So I traced it.

but it appears to be an ul;tra high mu valve high impedance clearly in need of class A2 testing which we can't yet do. Must be a low powered 811a type thing.

It is the size of a PX4 and same filament requirements.

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at least we now know!
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Paul Barker
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#2

Post by Paul Barker »

As shown above we discovered this valve is a positive grid voltage valve on similar lines to the 811a but lower powered.

It would be a candidate for Class B2 operation push pull, or class A2 single ended.

In both cases a very powerful low impedance driver is essential.

Realistically you would have to stop at something like 30mA grid current.

Just ignore the negative sign on the grid data displayed on chart, each step is +3v.

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Grid Current chart.

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Along the full linear length of the +3v curve the impedance is 30 kohm mu is about 50.
"Two things are infinite, the universe and human stupidity, and I am not yet completely sure about the universe." – Albert Einstein
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