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In Reply to: RE: Well if thats' the case.. posted by drlowmu on March 14, 2012 at 23:57:11:
OOps...
Just looked back at my earlier post and the link to the image is broken.
Since Xa and Xg play a major role on tube properties any variation effectively puts dissimilar tubes in parallel.
WRT the filaments, I envision the harp filament further increasing the possibility of two tubes in parallel with different characteristics.
below are the effective plate areas of a V and W filament.
We can see that the effective plate area is a "shadow" of the filament structure. When considering the single V filament it becomes obvious that the Xa (filament to anode spacing) from point A on the filamment to point A on the Anode will be different than the distance from point A on the filament to point B on the Anode. While one would think this would be bad, you also have to consider there are an infinite number of points between A & B all having slightly different spacings. The net effect of this is sort of like a bunch of slightly different tubes in parallel.
Now when you consider the SP 2A3 and its harp filament structure, the variation of the distances A and B will be less creating a more uniform set of filament to anode spacings, which one might consider desirable. However when you consider the possibility of the grid and anode structures not being symmetrical about the filament, you can now end up with two distinctly different structures in parallel. Now consider what happens with the single V filament and an asymmetrical structure about the filament. The larger variation is the spacings will give a much better chance of the distances of one overlapping with the distances of the other netting a more uniform range of characteristics rather than two uniform but slightly different sets.
dave
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- RE: Well if thats' the case.. - dave slagle 15:18:04 03/15/12 (0)
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