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CV3710 / AR63 excitron

This valve measures 385x90mm overall

This is an excitron: a single anode, continuously excited, grid controlled mercury arc rectifier.

Ratings for operation at 50 to 60Hz
Max PIV6.3kV10.4kV14.5kV
Max average anode current10A6.7A3.3AA
Max peak anode current60A40A20A
Excitation current range1.4 to 3.1A d.c.B
Grid voltage for sine-wave control50 to 150V r.m.s.C
Grid voltage range for impulse control100 to 250VC
Grid voltage negative bias for impulse control50 to 150VC
Max grid circuit resistance10kΩ
Grid voltage to prevent anode pickup-10V
Min cooling air quantity for max ratings40 Cu.Ft./Min
Max cooling air temperature for max ratings40°C
Min cooling air temperature5°C

A: Average anode current is the average of the instantaneous anode currents taken over a time interval not exceeding 15 seconds
B: The excitation anode is supplied with a low voltage from an auxiliary DC supply which maintains a continuous excitation current between the cathode and the excitation anode. This maintains a continuous cathode spot independent of the main anode current.
C: For control of the output voltage from the rectifier the grid is held negative with respect to the cathode until the instant in each cycle which the grid is made positive and current flows to the main anode.

The valve has the serial number 38050. The packaging suggests it contains 680 grams of mercury. The anode to cathode voltage drop is between 14 and 17 volts at full load, and about 20 volts at light load.

Connections are: cathode: screw base; excitation electrode: side cap; Grid: metal ring; Anode: top connector.


The graphite excitation electrode is designed such that the stray magnetic flux of a choke in series with the excitation supply and placed nearby will raise the electrode and strike an arc. The choke will hold the electrode up and maintain the arc while the voltage remains.

Grid detail, cathode cooling fins and connector. The cathode must be forced-air cooled with the air stream directed upwards onto the fins at about 45°. The valve must be mounted vertically, cathode down.

Grid baffles

Cathode fins
CV3710 / AR63