The VR136 is the pre-CV UK service designation for the commercial EF54. The valve is a VHF high-slope pentode and has a sharp cut-off. The cathode is brought out to several pins to provide a low inductance path, part way to a ring connection as found in co-axial valves. The VR136 has aligned grids to reduce partition noise and was developed from the EF50 during WWII. The VR136 was capable of operation up to 200 MHz.
The all glass construction is covered with an aluminium screening can in the same fashion as the EF50 et al.
The B9G base was one of the first used for all glass construction in the UK.
The red paint points to Mullard as the maker. The AM and crown indicate a product for the UK Air Ministry.
The B9G base pins are set into the hard glass foot. The metal spigot covers the evacuation tube and the key guides the valve correctly into the valve-holder. The nine pins are equally spaced around the pin circle.
The wide glass tube envelope is 33 mm in diameter and, excluding the B9G base pins, is 58 mm tall.
