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Milky white cloudiness behind silver getter flashing = bad tube?

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Posted on August 15, 2024 at 08:27:57
Funky Bob
Audiophile

Posts: 849
Joined: May 16, 2003



I see milky white cloudiness on the back side of the silver getter flashing but the front looks silvery and shiny. Is the cloudiness normal or the vacuum seal is getting leaky and therefore the tube is bad? Thanks.

 

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Maybe, posted on August 15, 2024 at 09:23:50
Sondek
Audiophile

Posts: 9930
Location: Fort Worth
Joined: May 17, 2000
Contributor
  Since: April 5, 2002
 All one can really say is that the getter is doing its job.

I would think that if the vacuum had been lost the getter would've gone completely off and filament probably blown. It either has a leak, or it doesn't.





 

RE: Milky white cloudiness behind silver getter flashing = bad tube?, posted on August 15, 2024 at 10:40:41
6bq5
Audiophile

Posts: 4564
Location: SF Bay
Joined: August 16, 2001
 If the vacuum is gone, there will be NO silver from the getter flash.
It will all be white/grey

a white-ish film on the inside of the flash area is a sign of age, as Sondek said-
not bad, per se, but getting towards the end of life...
Happy Listening

 

RE: Maybe, posted on August 15, 2024 at 10:45:58
Byrd69
Audiophile

Posts: 2934
Location: East Syracuse, New York
Joined: August 23, 2004
 There's some getter material out there that doesn't go white when it's exposed to air. I don't know what it is.

I broke a tube once and it did not go white. The pics were posted on AA.

As an experiment, I left the flashed portion of the tube sitting in a dish for months. It remained silver. It never changed.

I recently broke a tube and again, the flash did not turn.


Your interest may vary but the results will be same. (Byrd 2020)

I can't compete with the dead. (Buck W. 2010)

Cowards can't be heroes. (Byrd 2017)

Why don't catfish have kittens? (Moe Howard 1937)

 

RE: Milky white cloudiness behind silver getter flashing = bad tube?, posted on August 15, 2024 at 10:49:43
Byrd69
Audiophile

Posts: 2934
Location: East Syracuse, New York
Joined: August 23, 2004
 I see a lot of this on Sylvania 6SN7s. Don't know if it's the same thing. Sometimes it's quite evident, other times just a bit showing along the edge of the flash.


Your interest may vary but the results will be same. (Byrd 2020)

I can't compete with the dead. (Buck W. 2010)

Cowards can't be heroes. (Byrd 2017)

Why don't catfish have kittens? (Moe Howard 1937)

 

RE: Maybe, posted on August 15, 2024 at 17:49:28
Sondek
Audiophile

Posts: 9930
Location: Fort Worth
Joined: May 17, 2000
Contributor
  Since: April 5, 2002
 Now that you mention it I recall those pics you posted.

I wonder if it was somehow defective, or something different as you suggested?

 

How about white-ish coating on mica spacer?, posted on August 16, 2024 at 03:30:54
Funky Bob
Audiophile

Posts: 849
Joined: May 16, 2003



Like this one? Is it another sign of the tube is near the end of life? The tube in the picture still sounds nice though. Thanks.

 

RE: Milky white cloudiness behind silver getter flashing = bad tube?, posted on August 16, 2024 at 07:16:34
Triode_Kingdom
Audiophile

Posts: 10181
Location: Central Texas
Joined: September 24, 2006
 I don't think this is a reliable indicator of either tube life or performance. If the tube has a leak, it should show up in a tube tester as grid current.

 

RE: Milky white cloudiness behind silver getter flashing = bad tube?, posted on August 19, 2024 at 18:38:16
Jim McShane
Dealer

Posts: 5919
Location: Chicago
Joined: January 13, 2003
 That is totally normal - it doesn't indicate any sort of vacuum leak.

It sometimes appears in areas where the silver getter flash has been used up, and it also appears on brand new tubes - it happens during the production process.

 

RE: Milky white cloudiness behind silver getter flashing = bad tube?, posted on August 21, 2024 at 05:08:59
Funky Bob
Audiophile

Posts: 849
Joined: May 16, 2003
 So the cloudiness doesn't really mean anything and the tube is safe to use?

 

RE: Milky white cloudiness behind silver getter flashing = bad tube?, posted on August 21, 2024 at 11:10:38
Jim McShane
Dealer

Posts: 5919
Location: Chicago
Joined: January 13, 2003



That's correct, that bit of cloudiness is not an indicator of any issue.

If the tube had a leak it would affect the whole getter which would turn entirely white - see the picture above.

 

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