CV15 (E1266), low power version of the VT90 micropup without the anode fins and with a bolt-down heatsink for conduction cooling instead. It was used in the 70cm ASV (Air-Surface Vessel) radar at first, producing 10kW in push-pull pairs at 1µs pulses/1500pps. This radar later used the NT99.

Markings on the valve are 37K, P on one side of the block, and CV15 stamped on the other.

Cooling should be provided so that the temperature of the anode does not exceed 140C, even if just the filament volts are applied.