Re: Max anode voltage?

["Tesla list" <tesla@xxxxxxxxxx>]

Original poster: "Andrew Bonnell" <andrewbonnell@xxxxxxxxx>

Out of curiosity, how fast to vacuum tubes switch?

Andrew

On 5/17/06, Tesla list <<mailto:tesla@xxxxxxxxxx>tesla@xxxxxxxxxx> wrote:
Original poster: Ed Phillips <<mailto:evp@xxxxxxxxxxx>evp@xxxxxxxxxxx >

Original poster: David Speck 
<<mailto:Dave@xxxxxxxxxxxxxxxx>Dave@xxxxxxxxxxxxxxxx>

Robert,

If tubes are anything like light bulbs, you may take a significant
hit on filament longevity by running them at 10% overvoltage.  I read
somewhere that the life of an incandescent lamp varies as the inverse
cube of the current, so that works out to about 75% of the rated lifetime.

Dave

With 10% more filament voltage you can probably double the saturation
current."

    I think that the effect of overvoltage on life is even greater
than you state - there's information on it in my RCA Transmitting
Tube handbook but it isn't handy right now.  Depends on the filament
(pure tungsten, thoriated tungsten, oxide-coated, etc.).  On the
other hand, life is probably not much of a consideration in TC work
and some overvoltage is undoubtedly permissible.

Ed