The CV172 diode is a specially constructed directly heated noise source. The commercial device was designed by M-OV as an experimental product and given the designation E1468.
When operated in saturated mode the diode produces a calculable amount of shot noise and this controlled noise can be used to measure the noise figure (NF) of the front end of a receiver.
The American Radiation Laboratory commented on noise diodes for measurements on radar equipment that 'the British CV172 is the most satisfactory'.
The tungsten filament is a horizontal V held at the bend by a tensioning spring.
Each side of the anode is connected to large carbonised flanges.
The filament at the connection end. The far end shows the shape of the hook on the spring arm.
The wide glass tube envelope is 32 mm in diameter and, excluding the B9G base pins, is 56 mm tall.
