Virtual Valve Museum

Virtual Valve Museum

HomeFull List

This is an archive website. It will not receive any updates, additions or corrections.

CV221 X-band TR Cell

Size The TR cell measures 100x53x34mm overall. The apertures are approximately 22mm inside diameter.

The CV221 replaced the CV114. The prototype was E1365, developed in early 1942. It used a mixture of argon and water vapour at 6mm Hg pressure each. It differs from the CV114 as it has a tellurium copper body and gold ring seals for the window and diaphragm assemblies, which allowed the whole device to be clamped together and baked at 400C while being pumped to outgas the assembly - the temperature forming the vacuum seals by diffusion of gold into the mating copper surfaces. In September 1943 the E1365 was type approved as CV221 and production continued throughout 1946.


Nominal frequency at which spark-gap will operate 9375MHz
Minimum priming voltage -1000V dc
Continuous priming current 0.15mA +/- 0.05
Max. mean line power in equipment 100W



Side view
The tuning mechanism can be seen in these pictures. The device could be damaged if it was frequently tuned over its full range, and it was recommended that the number of tuning operations and the range of movement be restricted.

Tuning mechanism

Quarter view Quarter view