raindownthunda
500+ Head-Fier
This doesn't look like the RFT 6SN7 I've seen. I think it is a Telefunken.Speaking of Eastern European tubes, my tube man just let me another interesting one. This 6SN7GTA has Telefunken markings but based on his info and from here it seems likely that this is made by RFT. Curiously the ring getter looks very TFK-ish though…
I haven’t had the time to test it yet, maybe tonight.
For starters, check out the ribs and folds on the plates (vs flat, welded on RFT).
Here's a pic of the RFT 6SN7 (not mine, but same construction) from the internet:
Let us know how it sounds!!