What’s your understanding of ‘NOS’?

[Arkless Electronics]

The existence of valves sold by the likes of Edicron, Pinnacle etc but sourced from proper UK Mullard, Brimar alongside the much more common really crap East European and Chinese 1980's valves (some real horror EL84's that blow in 1m if fitted to a St20 come to mind) puts another cat amongst the pigeons...
Do they look like Mullard and do they have the correct etched ID in small digits near the bottom?

 

[Yank]

The only assurance you can have that something is NOS is tamper-proof sealed packaging. Anything else is dependent on the honesty of the seller and your own visual assessment once you have taken delivery.

Valves never came in tamper-proof sealed packaging.

 

[Tony L]

Valves never came in tamper-proof sealed packaging.

Indeed, here’s a early ‘60s Mullard ECC83:

It is very easy to damage the thin paper printed warranty that is wrapped around the card former, so you can usually tell if someone has been in there, but that could be legit just to test it was 100%, identify date-codes etc.

 

[Arkless Electronics]

Valves never came in tamper-proof sealed packaging.

You made me think there and yeah that's right IME. Mullard's "Kradlepack" was a backward step IMO as well!
The corrugated cardboard and tissue paper was where it's at... and a plastic bobbin with holes for the pins protecting the base in Mil spec and SQ versions.

A little of topic but in one of those "Did you know??" things... that even in the Mullard days valves only came with a 3 month guarantee! IIRC there was BVA stuff about how long the repair shop etc could keep them and note had to kept of when a valve was fitted to customers equipment by the "TV shop", space was there on many a valve packaging for "Set Type" "Serial number" "Customer Details" etc to be filled in.

 

[Arkless Electronics]

You couldn't make it up but Tony L just posted a picture with the bits that could be filled in visible whilst I was typing that last post!

 

[James]

When you are dealing with 50+ year old valves there is often no way of telling, e.g. I have a fair tube-stash, lots in their correct boxes, some are NOS, some I’ve used for a while, all are in good condition and test new or close to that. When I’m dead and gone whoever ends up with them certainly won’t know which are which! As such unless the source is well documented, e.g. a huge purchase from the military of sealed crates of 500 or whatever valves really all you can do is look at condition/measurement and try to predict. I prefer the term ‘likely NOS, measures 100%’ or whatever as there are often just too many gaps in provenance to know for sure.

Would a used valve exhibit scratched marks on their pins if they had been installed into bases? Or would simply testing them as part of the production process mark them as such?

 

[Vinny]

It is all urination in the breeze, wishful thinking.

Valves very seldom had tamperproof packaging - I stated that, back in post #19 - the only ones that I recall have been from Japanese manufacturers - and test results in many cases mean less than nothing. I have, very fortunately, bought just one dud and that was a Mullard (60's manufacture?????) that had OK test results and appeared as new.

 

[Barrymagrec]

The only new valve I ever bought was a dud - Mullard UL41, in1965, not even OS, lasted 15 minutes. Local shop replaced it no trouble though.

 

[Vinny]

Valves pulled from kit, even valves ex. military stock, are another can of worms.

Having lived through the time of the HUGE military stocks sell-off of the 60's-70's, (of everything imaginable, not just valves),I have seen endless amount of ex military stock that was indisputably totally unused - it had been spares. I have no doubt that obsolete electronic kit, never used, was sold off too, but back then, would anyone have bought it, leave alone pulled any valves?

I have also had an online conversation with someone who attended numerous MOD auction sales, including some at the former stores depots, and he said that he had never seen any valves offered for sale.

 

[Arkless Electronics]

As someone said up thread used valves with say 100 hours on them are often a safer bet than completely unused as such valves can just fail for no apparent reason in the first few minutes. A bit of use tests them, proves them.