Thought I would make this it's own thread, and do a quick poll about this. I noticed in my Penncrest CTC-15 clone, when I pulled the 6BK4 out, it jingled. The used tube that came with the set also jingled when it was tilted. What causes this? I know tubes like the 83 have mercury inside, and those can jingle or appear to have metal inside them, but a 6BK4? In both cases, I was unable to see anything loose inside the tube. And both tubes worked (although one failed after about five hours of use)

Another AK'er commented that he noticed jingle in his tube. Is this something common to all 6BK4's? A common failure? Coincidence?

Inquiring minds want to know. :)

-Ian

That's weird. I don't remember seeing any 6BK4s with loose parts inside; at least no more than any other tubes. I'd replace it. They're a dime a dozen. I don't think there's any way that the TV could have caused this. Probably just two tubes that were both dropped at one time.

Charles

Lumpy vacuum?

Loose chips of glue in the base bouncing off the bottom of the glass?

Dave A

I have a feeling that the 6bk4 will be a tube we'll never have to worry about running out of.

That's a pretty simple tube-not too much can go wrong. I haven't seen a pattern of rattles in them, but various tubes I've had over the years have done it. Sometimes a little piece of glass rattling around, or a chunk of glue in the base like Dave mentioned. Some tubes have insulators/seperators that will just naturally rattle.