Please help me identify this ECC83/12ax7

[jimmyride]

Hey guys!

I'm not a tube expert so please help me with identifying this one. I have absolutely no idea. I found it among a lot of old Tesla probably radio or TV tubes.

http://jimmyride.rajce.idnes.cz/ECC83" onclick="window.open(this.href);return false;

[bill bokey]

RFT
Great for Classic Marshall overdriven tone.

[jimmyride]

Thanks man! Do you know approximately from what era?

[bill bokey]

I don't know how to date them but I believe they stopped making them in the 80's.