6J5 (Metal Tubes) ....something goes around inside

[zxx123]

I bought 10 6J5s from an online site.
I feel some particles exist inside some tubes.
I don't what they are because they are metal
protected tubes.

My question is simple. Is it normal? Will these work?
Does it affect sound?

thanks.

[Miles Prower]

If you have something rattling around inside the can, that's definitely not normal. I've used 6J5s, and these certainly don't have anything loose inside. Given the sturdy internal construction, there's something awfully wrong there.

[tubelab.com]

My curiosity has convinced me to dissect many types of electronic items. I have cut the top off of some metal tubes, although it was a long time ago. I have found some metal tubes that rattled also.

I wondered about the construction of metal tubes, and if it would be possible to use the metal envelope as an extra electrode, so I cut a few open. The shell is metal. Most appear to have some sort of coating on the inside of the metal jacket. There is a glass to metal seal at the bottom where the leads come through. The construction of this seal is often sloppy. One example had extra glass drips extending up into the tube along the inside surface of the tube. If this were to come loose, it could be the source of the rettling components. This should not be a concern in normal operation.

It was several years ago that I cut some metal tubes open. I have a few zillion oddball tubes, so the next time I run across a rattler, I will cut it open for a fresh look. Just to be on the safe side it may be wise to avoid using the rattlers in a direct coupled circuit where a short could be fatal to expensive parts or tubes.