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Sensibly equivalent to:
4049D AH221 ESU200 GU21 RG4-1250
See also:
Ediswan Rectifier & Power Triode Advert - English Electric AX228 Advert
Extras ▼


The CV5 mercury vapour rectifier has a shielded oxide-coated filamentary cathode rated at 4V, 11A. Rectified current rating is 1.25A and PIV (peak inverse voltage) rating is 10 to 12 kV. The specification for the CV5 was based on a special version of the GU21.
Rectifiers of this class are normally used in 3-phase bridge arrangements incorporating 6 valves. The maximum output rating of the group of 6 rectifiers when used in this way would be 10,000 VDC at 3.75A, enough for a 20 kW transmitter.
Internal blackening around the anode to shield gap shows that this specimen has been heavily used (or misused) and has probably reached the end of its useful life. Mercury vapour rectifiers must be mounted vertically with cooling air blown upwards around the large expanse of clear glass seen below the region of the hot cathode shield. It is essential that hot mercury vapour expelled from the gap region should be cooled by circulation against the lower part of the glass envelope before being recycled. Almost every part of a mercury vapour rectifier is temperature-sensitive and failure to maintain the correct temperature in each part of the valve, even for only a few seconds when used at maximum rating, can cause permanent damage. In short, MV rectifiers are temperamental (excuse the pun).
In July 1958 English Electric advertised the AX228 a Xenon rectifier as a plug-in replacement for the CV5, it was also given the Cv reference of CV2399.
The wide glass tube envelope is 55 mm in diameter and, including the GES base, is 254 mm tall.
Reference: Data-sheet.


Absolute Maximum Operating Conditions
Thanks to Frank Philipse for supplying the above PDF datasheet.
Updated November 05, 2016.
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