ECC83 12AX7 ECC803S TESLA TELEFUNKEN TOOLING RHODIUM-PIN DOME-TOP SINGLE TUBE
NOS ECC83 / 12AX7 / ECC803S. So the original Tesla (NOT JJ) had access to the brains who knew about multilayer cathode information, etc. NOS MILITARY ECC83 / 12AX7 SINGLE TUBE! Tesla produced the tube for military as well as other sources.