The Z329 is a miniature screened pentode that was designed to operate at the standard TV intermediate frequency of 33 MHz. The IF stages in any superhet receiver are where the main signal voltage amplification takes place.
Through the dirt can be seen the strap connecting the two small plates of the anode. The open pitch of the suppressor grid can also be seen. The control grid is wound on copper supports.
The heat radiating fin on the top of the control grid supports.
The thin glass tube envelope is 20 mm in diameter and, excluding the B9A base pins, is 59 mm tall.