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CV1574 / CV1699 / CV1700 HF pentode.

Size The valve measures 95x33mm overall and has a Mazda Octal base

Although listed as separate CV numbers, each of these valves also carries the SP41 label. The only clues as to any difference are in the fact that the CV1699 is also known as PO VT150, and the CV1700 as PO VT150A, both being to GPO specifications. The CV1574, as indicated on the box of the VR65A pictured below, is shown on the EVS data sheet as VR65A.

Heater voltage 4V
Heater current 0.95A
Max anode voltage 250V
Max screen voltage 250V
Max anode dissipation 4.5W
Max screen dissipation 1.25W
Mutual conductance 8.5mA/V
Max operating frequency 60MHz


Pin Function
1 Heater
2 Cathode
3 Anode
4 Screen grid
5 Suppressor grid
6 Metallising
7 No pin
8 Heater
TC Control grid

VR65A CV1574 box
The VR65A's box marked CV1574. The label says "The Pattern Number shewn on this slip is the new designation of the Valve enclosed. Supplies should be taken on charge, and demanded under the new Pattern Number in future. S.N.S.O. Haslemere, December, 1943."






CV1574, left, but this example has no metallising.

Inside view

CV1699 CV1700
STC CV1699 above and SP41 markings on the rear, below.    STC CV1700 above and SP41 markings on the rear, below
SP41 labelling on CV1699 SP41 label on CV1700


Thanks to Chris Colebrook for donating the CV1699

This file was last modified 11:16:47, Thursday April 14, 2022