This impressive Russian RF power triode, owned by G3GRO, is a rebuild of an ultra rare WW2 German valve type LD9, and has the same physical size as the earlier German valve. The LD9 was originally made by Telefunken and had an anode dissipation of 40 W, and a maximum operating frequency of 3 GHz (9cm). Copies of the original exist in the form of the HT321 from the GDR and GK-60 in Russia.
The OTK stamp is a quality stamp of the Russian army and the valve is a GI-7B in the Cyrillic.
The valve has few connections, it is a directly heated triode. The large grid band is clearly visible below the purple ceramic insulator. The anode fins can only be described as substantial, they are also silver plated. The large fins will be less efficient than the folded ribbon used in the UK and USA. The anode dissipation is up to 300 Watts and operating frequency is up to the low GHz region.
The co-axial envelope is 67 mm in diameter and, including the base pins, is 109 mm tall.