The CV5413 (commercially the A2913) is a special quality low noise VHF amplifier triode. The anode dissipation is 2.5 Watts and the grid is of frame-grid construction. Lower noise figures were obtained by running at higher anode currents than one would expect for a small signal RF amplifier.
The GEC paper brand label indicates a valve for professional equipment. M-OV used Osram and Marconi for consumer products. This valve has gold plated pins - never seen in consumer products.
The double top mica indicates a valve for use in environments of shock and vibration - aircraft for instance. The control grid support is a brass frame to give the strength to resist deformation when the grid was wound under half breaking strain tension.
This image looks along the grid axis but the glass obscures the fine detail.
With much fiddling this image of the frame grid support and winding was taken with the microscope.
The thin glass tube envelope is 17 mm in diameter, and excluding the B7G base pins is 33 mm tall.
