Floating glass pieces in rectifier tube: DOA or cosmetic?

[Exophile]

I bought a NIB Western Electric 422A rectifier tube for my Woo WA6-SE headphone amp. It has some floating glass pieces in the very top of the tube (see pictures). Does that make the tube unusable/DOA? Or is this more cosmetic?

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[alphaGT]

So it’s just falling around in there? Seeing it’s just glass, and not all that close to any screens or anything, I don’t see how it can hurt? As long as there is nothing else wrong with it. Unless you can exchange it for a new one, I’d give it a try.

Russell

[Stryder5]

N G on the top, does it indicate No Good?

[Ali Tait]

Should be fine. This isn’t uncommon, they are left over from manufacture.

[Jazid]

A note of caution. It depends where the glass comes from. If it is indeed manufacturing waste then its inert so as long as it can't get in amongst the filament all should be fine.

But often this glass is broken from the joint which holds the metal support rods in place to the valve stem. Here it may also not matter, or it might still have tension that may increase as the valve warms up. It could then snap further and knacker the valve. I'd run it for a few hours keeping an Eagle eye on it before relaxing.

I have several like this with glass insid, most bits have clearly broken off internally. So far no valve has failed but I test everything before risking it.

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[Exophile]

Thanks everybody. So not clearly DOA, which is reassuring. Re "NG" that is *inside* the tube on the top piece, so could not have been put on there after manufacture.

I checked for any breakage point, particularly at base, as that was also one of my suspicions for source of the piece. The base seems very clean, no cracks or cleavage planes. I used to break glass knives for histological semi-thin and ultra-thin sections, so know what cleavage planes look like.

Re testing, the only thing I can do is putting it into the headphone amp and turn it on. Don't know what else could be done. Proof's in the pudding.

[Jazid]

If its going to go it'll be overwhelmingly likely in the first couple of hours as it heats up and tries any internal stresses. Just listen to music you can concentrate to

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[Exophile]

So like hard-drives. Either they fail early on, or they are good for a long time.