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CV490 rectifier. The EVS sheet describes it as a damping diode.


Size This valve measures 240x58mm overall and has a goliath Edison screw base


Heater voltage (a)(b)4.0V
Heater current4.0A
Max anode dissipation (b)(c)32W
Max peak inverse voltage
* under short pulse conditions (d)27kV
* under fault conditions (e)35kV
* under rectifier conditions (no load)20kV
Max peak anode current
* under short pulse conditions (d)10A
* under rectifier conditions (f)1.0A
Max RMS anode current350mA
Internal resistance (g)105Ω

(a) The cathode is connected to the centre of the heater. Refer to the EVS data sheet.
(b) Anode voltage must not be applied for 30 seconds after switching the heater on.
(c) This may be increased to 38W provided the PIV does not exceed 75%.
(d) For pulses of 2µs or less.
(e) Under short pulse conditions, provided the fault does not persist for more than 50 milliseconds.
(f) If necessary a resistance of up to 1600Ω must be added to the anode circuit to limit the peak switching surge to 6A.
(g) At Ia=8A.

The base centre and outer are the heater and the top cap is the anode.