The technical point here was that the filaments evaporate over time. No
one was saying that one could not use DC to power filaments , just that
there was an observed lifetime difference when using DC where one side
of the filament would tend to plate/evaporate differently over the life
of the tube. The static electric field across the filament would
evidently cause a migration of the metal. Running on AC would cause a
more uniform evaporation and thus a higher filament resitance instead
of an open at one end.
---
Ron
MorgusMagnificen@aol.com wrote:
>
> Those who are opposed to DC on filaments should immediately notify the
> Department of Defense, as they have apparantly being erroneously doing this
> in all of that aircraft electronics since the days of the Wright Bros.
> (almost).
>
> Remember the 1625? It was an 807 with a specially re-designed filament
> to run on 12VDC, with two of them (wired in series) in the ARC-5 TX's powered
> directly from 24VDC.
>
> Eric von Valtier K8LV
>
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