The VR108 is an HF pentode to an RAF specification. The Type was later renamed the CV1108 when the CV system was introduced to standardise procurement across all branches of the UK Government.
The prototype for the VR108 specification was the commercial 8D2. The 8D2 is electrically identical to the 6J7G except for the 200 mA 13 Volt heater - designed for series heater chains.
In addition to the VR108 the base also carries the old stores code of 10E/11096.
Testing station or stores NAPL 102.
The outer perforated screen and lower circular screen plus the ends of the grid supports. The heater passes several times through the cathode tube as is normal with valves for low current series heater chains.
The AM and Crown for the UK Air Ministry.
Looking up from the base there looks to be ten passes of the heater through the cathode.
The top of the screens showing the control grid connection to the top cap.
The classic envelope is 37 mm in diameter, and excluding the B7 base pins is 97 mm tall.
Reference: Data-sheet. Type VR108 was first introduced in 1934. See also1934 adverts.