The QQV06-40A is a 1950s European pattern double beam tetrode VHF transmitting valve. The European pattern had internal neutralising unlike the American pattern valves such as the 829B that required external neutralising capacitors to prevent oscillations.
This exhibit has the later logo and QQV-06-40A has the older one. More details can be found under the other exhibit.
The glass envelope is 74 mm tall. The pins and top anodes are not gold plated and have started to corrode. The small wires at the top form the neutralising capacitors. The notch in the beam plates allows the screen grid to be glimpsed.
The anodes are grey and the beam plates are bright. In the centre the grid wires can be seen with the white coating on the cathode behind. The neutralising capacitor wires are on the extreme right.
A diagram showing the formation of the neutralising capacitors.
A close-up view of the aligned grids. The screen grid is easily seen and slopes slightly to the left. The fine control grid wires are vertical.
The wide glass tube envelope is 44 mm in diameter and, excluding the B7A base pins, is 91 mm tall.