Quality tubes for military equipment. High-quality tubes have thick gold-plated grids.

There is a legend that these tubes were made on captured German equipment and materials that were taken from Germany to the Soviet Union after the end of World War II. Which could very well be true.

Tested with L3-3 tubetester at Ua=250V, Ug2=250V, Ug=-14V Uf=6.3V DC

Results:

 

1t.  94uA ; S=6.2uA/V 1953 august (brocken socket key) - sold

2t.  91            6           1953 februry (brocken socket key) - sold

3t.  91            6.3        1956 sep      - sold                                  

4t.  89            5.7        1952 nov      - sold