[Amps] Incandescent and tube filaments tspa

[John T. M. Lyles]

One thing to consider when comparing these, is that the filament in a 
lamp is lit to incandescence, higher temperature, than the filament 
in a TT or oxide cathode filament. These are typically less than 
2000K, dull orange or less for oxide cathode. Also, the light bulb 
filament, does it use thoria in it or is it pure tungsten? Way 
different mechancially. Finally, the light bulb filament, in my 
recollection, is coiled like a tiny spring, or so i thought. Tube 
filaments are bars, strands, sometimes coils, but much different 
geometry. In some tubes they are tensioned with a mechanism to allow 
for changing dimensions when they warm up.

John
K5PRO

>
>I wonder if the filament life of an ordinary incandescent light bulb relates
>to that of an RF power tube.  One can fairly easily see the vibration set up
>in the light bulb filament at turn-on.  I guess the vibration is caused by a
>combination of AC voltage cycles and heating of the filament.
>
>73, Keith NM5G