The 5763 is a small transmitting beam tetrode valve for HF and low VHF use and is equivalent to the Mullard QV03-12 and both Type designations are printed on the glass.
Below the top mica the shaped grids can be seen.
Here the cathode tube can be seen to have flat sides and rounded ends. Two wire grids are visible, both run flat across the cathode and the control grid looks to be gold plated.
The thin glass tube envelope is 21 mm in diameter and, excluding the B9A base pins, is 58 mm tall.
References: Data-sheet & 1040. Type 5763 was first introduced in 1949. See also1949 adverts.
