The 3E29 is closely related to the 829B American pattern VHF double tetrode and has the same pin connections. However, the 3E29 is specifically designed for pulse modulator service rather than for use as a VHF PA.
The maker's identification etched into the glass. Inside are the two beam tetrode sections seen along the grid axis. The anode join flanges are at the centres of the working faces.
The control grids are wound on copper supports.
One anode seen face on. There are three flat projections at the centre of the anode.
The wide glass tube envelope is 50 mm in diameter and, excluding the B7A base pins, is 91 mm tall.