Problem with Tung Sol 5998 (solved)

[buddha2015]

Are you saying the tube was unpacked and photographed at a shipping Depot?    You can clearly see the getter starting to erode in those first few pics which implys to me that is when it got damaged.

Yes it was unpacked and photographed. The getter starting to erode ? How do you see that ?

[mcandmar]

When new the getter material would have had a shiny mirror coating on the glass, your tube is unusual in that had the getter material on the top and on the side.  In those pics you can see the top circle is getting smaller as the outer ring is still visible.  Likewise on the side the material is being eaten away from the center of the material out.  Eventually that material will turn milky white once it has fully reacted with the air. In your last pic there is no visible trace of the getter material, all that will remain is a white power floating around inside the glass.  The fact the materiel is visibly reacting with air tells us that the tube had already started to leak at that stage. i.e. it was damaged before you received it.

[buddha2015]

Do you mean it must have been damaged before it arrived at the depot ?

How long does it take the getter material to react with air/to be eaten away ? Is that a process that takes seconds, hours, days ?

[mcandmar]

I dont know how long it takes, i've never broken one to find out

[Doc B.]

The getter turns white nearly instantaneously when the vacuum is lost. That tube is definitely dead.

[buddha2015]

Hi folks,

someone is offering two 5998 tubes and claims that they are both working.
I seriously doubt that when I look at the picture that has been posted with the ad (please look at the right one, the silvery material on the inside of the tube is missing):
(https://forum.bottlehead.com/proxy.php?request=http%3A%2F%2Fabload.de%2Fimg%2F_57q8kfc.jpg&hash=cd943a716bb67e87742509ed2fad909d9f920481)

What is your opinion ?

Thanks
G

[mcandmar]

The getters and getter material are on the bottom of the glass in the early versions.  Personally i think those versions sound better too. The same differences can also be found in the TS 421a tubes.

[buddha2015]

You mean they could be from different batches ?

[mcandmar]

Different years of manufacture, so yes.   The other obvious difference is the plate colour, early tubes had a light grey colour, where as later years had a dark black, almost shiny finish.

[buddha2015]

The seller just confirmed that the tubes are from different batches and indeed one has the getter on top, the other one on the bottom.
Thanks for your help, mcandmar !