Actual pictures. Rare soviet military control test stamps. Tested with L3-3 tubetester at Ua=250V, Ug=-8, Uf=6.3Vdc
results:
1tube 1t Ia=8.6mA ; S=2.5mA/V
2t 7.8 2.4
2tube 1t Ia=6.7mA ; S=2.25mA/V
2t 8.6 2.4
30 $ per one tube.
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