The CV172 diode is a specially constructed directly heated noise source. The pressed glass base was developed by Mullard in 1938 and this must date from before the 1941 introduction of the CV system by virtue of its low CV number.
The American Radiation Laboratory commented on noise diodes for measurements on radar equipment that 'the British CV172 is the most satisfactory.
The anode side panels with the diode running from left to right. The base has equi-spaced pins and thus the key on the spigot is essential to ensure the correct orientation in the holder.
Looking into the diode anode. The single V filament is clearly seen.
The tension on the filament is maintained by the spring at the far end.
The additional information on this valve was supplied by R J Sutherland.
The wide glass tube envelope is 32 mm in diameter and, excluding the B9G base pins, is 56 mm tall.
