This sad little valve was an ebay find. The vacuum has gone as has any identification. The base shell is metal with a composition insert holding the pins.
If anyone can identify this exhibit, please let me know.
The cylindrical anode is a single sheet folded to shape. The brass pins are of the simple split-pin construction.
The helical grid is set close to the anode. The filament has burnt out but the supports suggest that it was a single loop fixed at the base.
The pinch and electrodes. Note that all electrodes are fixed only at the pinch, there are no top supports.
Looking down through the valve. The broken pip is central and the anode is at a slight angle.
A close-up of the anode and grid. The glass is pitted.
The balloon envelope is 39 mm in diameter, and excluding the B4 base pins is 63 mm tall.
Reference: Observation. Type R Type was first introduced in 1916. See also1916 adverts.
