[R-390] maintenance

[Roy Morgan]

At 05:25 PM 6/21/2007, Ed Zeranski wrote:
>Neat post!
>
>Age of New Old Stock does not appear to effect the life of tubes.

But, of course, manufacturing defects can show up long after manufacture.

>         I'm not sure what happened with a couple of sticks of 6C4s I had 
> once. All
>10 were NIB RCA but developed grid-cath probs after a few hours use.

I bought four unused in the box Western Electric tubes at a fest.  They 
were modest in price, unlike some of WE's products.  My tube tester (gasp!) 
showed they all were kaput.  Extra warmth on the envelope with filament 
power only led me to suspect that "all the vacuum had leaked out".  Close 
inspection showed shorter than normal tip pinch-offs (these were 9-pin 
miniatures), and a little line of "bubbles" through the tip. I suspect they 
all had leaked slowly after manufacture and testing - most unusual for 
Western Electric tubes!

Roy




- Roy Morgan, K1LKY since 1959 - Keep 'em Glowing
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