CV1574 / CV1699 / CV1700 HF pentode.
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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 |
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."
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CV1574, left, but this example has no metallising.
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| STC CV1699 above and SP41 markings on the rear, below. | STC CV1700 above and SP41 markings on the rear, below |
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