Heater Voltage Range, Hi or Low

[Diabolical Artificer]

Thanks Merlin, much appreciated, will treat with skepticism.

 

[v4lve lover]

TEK found that the tubes in the vertical amps of their 540 scopes had a problem called 'interfacing'.
A layer of material formed under the outer layer of emitting material, in circuit it looked like
a poor conduction layer in parallel with a capacitor under the surface.
The problem was fixed using 6DK6 tubes, my recollection there were 12 of those in the vertical amp.
The amplifier in this case is a PP Distributed design, something we won't find in audio.
But there could be tubes, both new & used that might have the 'Interface' problem.

There are certain cathode nickel formulations that are specified to avoid this problem.

I had quite a few Tek scopes, and later models switched to industrial variants of 6DK6.

 

[tiefbassuebertr]

http://www.tubebooks.org/Books/Atwood/Tomer 1960 Getting the Most Out of Vacuum Tubes.pdf

(It's not really a serious academic book, take what it says with a grain of salt)

http://www.tubebooks.org/Books/Atwood/Tomer 1960 Getting the Most Out of Vacuum Tubes.pdf

 

[tiefbassuebertr]

http://www.tubebooks.org/Books/Atwood/Tomer 1960 Getting the Most Out of Vacuum Tubes.pdf

(It's not really a serious academic book, take what it says with a grain of salt)

URL from my post #38 are wrong - here we go
http://www.tubebooks.org/Books/Atwood/Tomer 1960 Getting the Most Out of Vacuum Tubes.pdf

 

[Diabolical Artificer]

TEK found that the tubes in the vertical amps of their 540 scopes had a problem

All I can find is a TDS540 scope which has no valves in, AFAIK. Interesting phenomenon though which I'll look into. Also are you referencing direct coupled vertical amps?

A few posts crossed there, thanks all.