The RV12P2000 is a 'universal' HF pentode, possibly close in design to the American Acorn valve 954. The base has side pins and a knob screwed into the end of the base to act as a handle. This base arrangement prevented the stress on the glass to metal seal of the pins that caused problems for the Acorn types.
The RV12P2000 was produced in quantities larger than any other valve for the Wehrmacht. It was used in many stages of a a piece of equipment. The design allowed for it to function in RF stages up to the low VHF and even to generate up to 580 mW of output. It was also found as an oscillaror, IF amplifier, audio amplifier and we believe also, in some cases, as a rectifier.
The frosted glass also carries the work Kriegsmaring, indicating that it was made for the German navy.
The valve from the base showing the arrow pointing to the locating spigot at the top of the image.
A side view showing the lower mica through the frosted glass.
The valve from the top.
Another example but with clear glass. The mica supports hold the electrode assembly in place. The 20 mm diameter tube is the same size as the B9A based valves of a decade or more later. Wires pass through the glass foot to attach to the side bins through the Bakelite base. Another sample shows that this clear glass was later sprayed with zinc paint to form a screening layer near the top of the envelope. This layer was grounded within the equipment and not through the base pins.
The Telefunken logo on the outside and near the top inside is the getter holder.
The top cap connects to the control grid.
The grids can be seen in this image. If the tube is 20 mm diameter the anode cylinder is 10 mm in diameter.
Here all three grids can be seen. The outer helix of the suppressor grid is wound to a wide pitch. The screen grid is much closer to the central coated cathode with the control grid slightly larger than the cathode.
The thin glass tube envelope is 20 mm in diameter, and excluding the base pins is 57 mm tall.
Reference: Data-sheet. Type RV12P2000 was first introduced in 1937.