HERE FOR SALE IS A VINTAGE PAIR OF MULLARD ECC83 / 12AX7 VALVE. WITH PRE YELLOW LOGOS AND LARGE RING GETTERS, THEIR FACTORY CODES ARE 161 B9F AND B0H WHICH HAS COPPER POSTS. THEY WERE BOTH MADE IN BLACKBURN IN 1959 AND 1960.

HICKOK TEST RESULTS ARE AS FOLLOWS:

GAS TEST:     PASSED GOOD

SHORT TEST: PASSED GOOD

NOISE TEST:  PASSED GOOD

VALVE 1.

Triode 1:  gm: 1.05mA/V  (1050 micromhos)....88%

Triode 2:  gm: 1.15mA/V  (1150 micromhos)....95% 

VALVE 2.

Triode 1:  gm: 1.05A/V   (1050 micromhos)....88%

Triode 2:  gm: 1.1mA/V  (1100 micromhos)....92%

• MINIMUM GOOD gm: 0.82mA/V (820 micromhos) 65%
• HICKOK NEW AVERAGE  BOOK SPEC:  gm 1.25mA/V (1250 micromhos)....100%
• FOR ECC83 / 12AX7.                                 gm 1.25mA/V (1250 micromhos)....100%