Re: 833A's plate color

["Tesla list" <tesla@xxxxxxxxxx>]

Original poster: Mddeming@xxxxxxx 


Hi Henry,
I agree that the cooler a tube runs, the longer it will last. 
However, when the developer/manufacturer of the tube (RCA) states 
explicitly in their literature [1]
"Plate shows an orange-red color when tube is operated at maximum CCS 
or ICAS ratings", on whose part is the ignorance you refer to?

(1) RCA Technical Manual TT-5, page 146

Matt D.



In a message dated 3/25/06 12:56:33 P.M. Eastern Standard Time, 
tesla@xxxxxxxxxx writes:
Original poster: "Henry Hurrass" <dr.hankenstein@xxxxxxxxxxxxx>

I think the suggestion that a power tubes' plate is supposed to glow a
"dull red" during normal operation is ignorant. If the plate is glowing,
the plate's maximum dissipation is obviously being exceeded and the life of
the tube(s) will suffer due to, in part, the following factors:

Plate voltage too high.
Grid voltage too low, (too small value grid leak resistor in tesla coils),
causing excessive plate current to flow.
Plate circuit out of tune.

Of course, it is tempting to observe and enjoy the longer spark that occurs
when we "max out" the plate dissipation of our transmitting tubes; but
remember, you are exceeding the maximum design parameters of the tube(s).

If you want your tubes to last for years, I would never advocate running
them with any kind of 'glow' other than the filaments. This is good just
plain good design etiquet. But thain again, they're you tubes, so if you
want to run them in 'supernova', be my guest. Just remember what others may
be thinking when they watch your TC's plates overheating.

Dr. Hankenstein