KT66 OUTPUT BEAM TETRODE MATCHED PAIR CLEAR GLASS BROWN BASE SAME FACTORY CODE FROM APRIL 19647
Well, here's a tasty pair of device both clear glass "coke bottle' KT66 in GEC livery.
The device carries markings in excellent white ink, a classic GEC/M-OV military cartouche with a date code of UD which equates to April 1964 and factory code Z which indicates Highgrove manufacture. . The brown low loss micanol bases are both tight to the valve envelopes.
These devices have been tested using our AVO VCM163 against the specification for 100% emission of anode current, Ia =63 mA; mutual conductance gm = 6.3 mA/V @ At Va = 250V Vg = -15V.
The results obtained were:-
Ia1 = 73 mA.
gm1 = 5.9 mA/V.
Ia2 = 73 mA.
gm2 = 5.8 mA/V.
These test figures indicate a very strong pair of devices with supreme matching, truly a superb matched pair - not to be missed.