Foregoing warranty rights
 

On Sunday, April 3, 2011 4:15:48 PM UTC-7, David Nebenzahl wrote:
On 4/3/2011 5:29 AM Geoffrey S. Mendelson spake thus:

So--and this is completely out of left field, I know--what would happen
if a guy put a vacuum tube--say a biggish octal one, like a 5Y3 or a
6V6--into a microwave and nuked it?

You mean, 'nuked it AGAIN', don't you? The usual manufacturing
of vacuum tubes is finished off with pumpdown, sealing, and then
running an induction coil to heat the little loop-thing
that evaporates a bit of metal (like sodium). It's called 'flashing',
and the silvery deposit ('getter') on the inside of the tube is intended to
be an oxygen scavenger for the long lifetime of the device.

In the case of photomultipliers, it is also done to create the photocathode
layer, often of some alloy that cannot be usefully blended until there's
a vacuum.

Foregoing warranty rights
 

On Mon, 04 Apr 2011 13:36:49 -0700, whit3rd wrote:

On Sunday, April 3, 2011 4:15:48 PM UTC-7, David Nebenzahl wrote:
On 4/3/2011 5:29 AM Geoffrey S. Mendelson spake thus:

So--and this is completely out of left field, I know--what would happen
if a guy put a vacuum tube--say a biggish octal one, like a 5Y3 or a
6V6--into a microwave and nuked it?

You mean, 'nuked it AGAIN', don't you? The usual manufacturing of
vacuum tubes is finished off with pumpdown, sealing, and then running an
induction coil to heat the little loop-thing that evaporates a bit of
metal (like sodium). It's called 'flashing', and the silvery deposit
('getter') on the inside of the tube is intended to be an oxygen
scavenger for the long lifetime of the device.

In the case of photomultipliers, it is also done to create the
photocathode layer, often of some alloy that cannot be usefully blended
until there's a vacuum.

They use getters in metallurgy to absorb impurities. The getter is
actually the "little loop-thing" and not the deposit that is a byproduct
of the flashing. Some getters are made of a special material and don't
need flashing. Don't ask me for a tube number. Tubes with graphite plates
don't need a getter as the graphite absorbs impurities.



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