Virtual Valve Museum

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CV1120 / CV1290 halfwave rectifier

Size The valve measures approx 135x45mm and has a 4-pin base

See below for more examples of this valve.

Heater voltage 2V
Heater current 1.5A
Max applied RMS voltage 5kV
Max working PIV 14kV
Max no-load PIV 15kV
Max mean DC rectified current 5mA
(CV1290/SU2150A version) 10mA
Max peak anode current 100mA
Max reservoir capacitor 0.25µF
Min limiting resistance introduced externally 10k ohm


Su2150a internal view SU2150a mica shield
Internal views. The mica shield presumably protects the electrode structure from the getter.
Pin Function
1 n/c
2 n/c
3 Heater/Cathode
4 Heater
TC Anode

The CV Register shows the CV1290 as equivalent to the SU2150A, and the CV1120 as a possible replacement. However the example in the first picture above shows both SU2150A and CV1120. See also CV1001

Elliott CV1120 in a different bulb CV1120
Cossor SU2150A example showing a different internal structure.SU2150A Another Cossor example, this one also carrying 10E/121 and a screw top cap
Another CV1120 CV1120
Westinghouse Radiotron VU120, again with a different internal structure. VU120
NU33 NU33