> My hypothesis is that resistance between pin and socket
> electrode at the
> filament pins was both reducing the amount of filament
> voltage on that one
> tube and causing overheating at the tube pin, which
> eventually melted the
> solder and also detempered the spring clips. Because
> there wasn't enough
> filament voltage, the tube was taking less than its share
> of the load.
He actually could have one of four problems:
1.) Someone might have floated the grids with glitch
resistors (a very bad idea) and one tube could have an open
2.) One tube might be low on emission either through low
filament voltage at the tube or a low emission filament
3.) Somehow the RF drive or loading could be unequal.
4.) The tube might have internal problems resulting in more
concentrated current than the other tube has, perhaps a
broken grid wire. This can hot spot one area of the anode.
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