Why so different plate size for same model?

[Elerion]

How about this little beauty, 21st century ECC83 with a direct connection to Mullard ...

Nice 🙂

 

[kstagger]

Ah - weren't those E813CC's microphonic or ? I remember the initial excitement when they came out but then... crickets. I assumed the company folded.

 

[Kay Pirinha]

These are based on CRT structures, aren't they?
Best egards!

 

[Sorento]

As always, there are many ways to skin a cat.
Btw, I'd be quite interested in how they calculated the structural topography to yield a certain goal.
Best regards!

Have a look at this book from RCA Vacuum Tube Design 1940 http://www.pmillett.com/tubebooks/Books/Atwood/RCA 1940 Vacuum Tube Design.pdf
e.g. Mu calculation formula is in Lecture 20 on page 194 ...
There is also a 1963 revised and extended version on pmillets site http://www.pmillett.com/tubebooks/Books/Atwood/RCA 1962 Electron Tube Design.pdf