The VT75A is a war time development of the television line output valve type KT44 and as such was designed for anode surges of up to 8,000 Volts and boasts an anode dissipation of 26 Watts.
The VT75A is fitted with a B7 base the 'T' variant was designed for a slightly higher maximum anode voltage than the original KT44. It is not clear if the use was as part of the RF chain or the modulation side of a transmitter. The VT designation clearly marks this as a transmitting valve for the RAF.
Our other VT75A has a different construction and no envelope lettering. Probably not made by M-OV.
The box anode with side flanges.
Through the holes in the anode end plate the inner electrodes can be seen. The bright angled beam forming plates are top and bottom of the view inside the anode. The grids are shaped to pass flat in front of the working part of the cathode and aligned.
Another view of the grids and the copper support for the control grid.
The literature says that the VT75A was a special 'T' variant of the KT44. Only just partially visible to the naked eye was some etched lettering. With dark-field illumination this valve is revealed as a standard KT44.
The classic envelope is 56 mm in diameter and, excluding the B7 base pins, is 132 mm tall.
References: 1043. Type VT75A was first introduced in 1939. See also1939 adverts.