For Tube Folks...

My question -  Within reasonable certainty, is this tube is NOS or is it USED?  

@inagroove Just look at the pins of the tubes. If you see scrapes along them the tube has been inserted into sockets a few times. An NOS tube will have no scrapes.

The pic you show has a very large side-getter patch (good), with light-gray fringes that indicate some light use - roughly consistent with the seller’s description. As use continues, the side patch typically shrinks (well before the top patches), with the fringing sometimes becoming more dominant. I have some GE 7581A with chrome side patches and NO fringing, that are probaly truly NOS. Anyways, to see a very large side getter patch on a power tube (dark metallic or chrome, NOT chalky white/gray or brown) is usually a good sign. (note: if you see a side patch on a tube that shouldn’t have a side getter, like an EL34, that’s bad news lol)

The debate on "NOS" nomenclature is boring semantics. NO I wouldn’t call this tube strictly NOS, but these days very few tubes left are. If the seller’s description is accurate, and seller can be trusted, I’d be happy with ’em.

+1 atmasphere

I examined the pins when I cleaned them.  All showed light-ware - a sheen that indicated they were inserted into a socket.  I was not alarmed because the seller's description indicated that they had been tested and had some burn-in hours.  Perhaps I should have thought twice...  

"An excellent lot, matched to within 5 percent and then aged in a hi-fi shop demo unit. Very low hours, burn-in time only, and the performance has been verified by us..."

Regards,

+1 mulveling

Thanks for the details regarding the side-getter patch-chronology - very helpful.

As a novice, this is my first tube with a side-getter as well as my first 'NOS' tube purchase.  If I purchase another, I will be better informed...

Regards,

NOS   New Old Stock, usually from old inventory from out of business retailers. Boxes can show significant shelf wear.