Telefunken red tip

does the body of the tube have a rectangular 'spot' anywhere on it?

something that looks like there may have been a cloth sticker on it at some time?

... there are lots of rumors about the red tip tubes; dunno if any of them are true... medical useage is one of them (more reliable)

put a magnifier on it and see if the red tip is paint or inside the glass

the stickers were used to mark Telefunky tubes as of select quality - red tips if real and never stickered could mean a lot of things...

OTOH, has tube manf. technology improved much since ALL Telefunky tubes were made?

and who would make better tubes than the Germans?

so if you don't have the Porsche of tubes, you probably have the the BMW of tubes