866a tube Fivre Pair valve vapor rectifier FOR amplifier project with tubes 211 gm70 845 3b28 866

nos tube super strong emission tv7 tube tester results 54 / 50 ( reference good is 40 ) yellow label made in Italy ultra rare to find

866a Fivre Tube Made in Italy Ultra rare to find
tested super strong
cup getter
same yellow label on each tube
same Oldest production with oldest 866 Fivre logo
ultra rare to find Made in Italy
oldest production strong long life

both tubes with Black base

866A = CE-866 = GU12 = RK866A = GL866A = VT-46A = DQ2 = RG3-250A = 2XM600A = P600_Mazda = AG866A = ML-866A = DR-866A = WL-866A
Similar tube:   38166A ; DCG3/1000E ; R3_Rectobulb
Other class quality:   866AX ; CV32
Other base:   866E
Multiple differences or of other kind:   3B28 ; DCG4/1000G ; DCX4/1000 ; R66 ; SS-866A

Socket  UX-Base 4 Pins 2 thick Top contact with a cap
Transmitter tube

Filament Heater    Vf 2.5 Volt / If 5 Ampere / Direct / Parallel, ~ = (AC/DC)
Work started on the development of this tube at the GE laboratories in the summer of 1932 and it was assigned the type number early in 1933. It was released to the public in April of that year.  

box 65