The RCA Type 34 is described as a super-control RF amplifier Pentode. As the mutual conductance varies with grid bias it is assumed that that the description refers to a Vari-μ characteristic.
The RCA logo plus the circular screen and additional shield below.
All the electrodes of this battery valve can be clearly seen in this image.
The top mica components. The filament tension spring connects to a support that lies behind the control grid support in this image.
The classic envelope is 44 mm in diameter and, excluding the UX4 base pins, is 105 mm tall.
Reference: Data-sheet. Type 34 was first introduced in 1936. See also1936 adverts.
