Sensibly equivalent¶ to:
This exquisite R Type valve is smaller than the usual varieties and the grid is smaller and wound to a finer pitch. We believe that this was made in Europe after WW1.
Another R Type in the museum has a very similar construction externally and the etching on the bulb says that was made in Holland.
Seen end on the electrode structure and the intact tungsten filament can be seen. Tungsten filaments of this age are extremely fragile.
The type designation is missing from the envelope but operating voltages are etched into the glass. The filament is designed to operate on 4 Volts and the anode supply can be between 60 and 100 Volts.
The balloon envelope is 48 mm in diameter and, excluding the B4 base pins, is 80 mm tall.
References: Private communication, 1005 & 1003. Type R Type was first introduced in 1916.
Absolute Maximum Operating Conditions¶
Updated July 12, 2017. shape:balloon construction:pinch type:triode age:pre.1920 base:b4 heater:4.0v pins:4 pin:1.a pin:2.g1 pin:3.f pin:4.f