This EX EQUIPMENT TESTED example carries only a slightly smudged military cartouche in white print and shows a production date of March 1954. The base is brown low loss micanol and is tightly secured to the glass envelope All pins are bright and corrosion free. This device is used, ex equipment but has been tested using my AVO VCM 163 valve tester and as you can see from the test data presented below, it gives data for anode current, Ia and mutual conductance gm that is within nominal Mullard 100% emission spec:-
At Va = 250V Vg = -4.6V
Section 1: Ia = 6.0 mA; gm = 1.7 mA/V
Section 2: Ia = 7.0 mA; gm = 2.0 mA/V
The specification for a new/100% emission valve is:
Ia =6.0mA; gm = 2.3mA/V
As you can see, these results show a strong device with extremely good matching of each triode section within each valve envelope.