Michael A. Terrell wrote:

- heating before applying anode voltage,
- avoiding long periods without anode current,

Useless on low power vacuum tubes that are not used in some bizarre
circuit. Its a different matter on high power transmitter tubes.

Your kind posting shares a property with many usenet postings:
It provokes the most valuable question: "Why?".

Why, what? Have you ever seen any provable problems with low power
receiving tubes, or ar you just another tube freak repeating fairy tales
and folklore? Do you have decades of real experience with all types of
vacuum tubes behind you, or are you YAKIAH?

Is it not funny, that in many old tube radios you find ECH81, where
the triode part is deaf, whereas the heptode part still works fine?
One may assume, that the triode (oscillator for AM) was mainly
left without current, because people preferably listened to FM.

Why do tubes go?

Obviously what goes is the cathode. Obviously it does not burn,
like the wires in light bulbs. It loses the ability to emit. Now why
is that?

Regards,
H.