The E947 is an experimental or development sample valve from M-OV. No details can be found.
Looking closely it can be seen that the valve is a hexode with grids 2 and 4 strapped together. The control grid has heat radiating fins at the top of the supports and connects to the top cap. With two screening grids g3 will be for local oscillator injection.
The heater takes 1.3 Amps at 6.3 Volts. This heater power would indicate a considerable cathode current. This could indicate a design aimed at low mixer noise.
This exhibit carries the serial number 2.
The M-O Valve company identification etched into the glass.
The top mica. Note the strap between grids two and four below the centre line.
A attempt to get an image of the lower mica. The heater is a single hairpin.
The classic envelope is 45 mm in diameter, and excluding the IO base pins is 119 mm tall.