any clues? on mystery TOOBS...

I found a Quad of Tubes! no markings other than 6H1C ? no brand name on them? diamond logo, or stamp w/the #30
inside of it...or the other marking is a big circle with the (6H1C) inside of it. So can you help a brother out, and tell me what these are?
thanks in advance
I did find a 6H1 tube. See
thanks, but it comes up BLANK?
Most likely Russian origin. They a have a different code number than Western tubes.