RZ1-150 Mullard 4 Volts heater directly heated audio rectifiers akin 5R4GY L4 base rare

Description

The Mullard RZ1-150 is a versatile valve in that it works at 4 Volts heater. It is a 1000 Volts Anode valve introduced in 1934.

The pair RZ1-150 we have for sale are about that date with balloon shaped top and long anode.

Getter is located on top.

Base is L4.

Both tested and in working order.