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The UBC41 is an early all glass valve and less clear or free from imperfections than later valves. This is a double diode triode valve on a B8B base. Mullard describe the UBC41 as a high gain triode for use as an AF voltage amplifier, combined with twin diodes, for DC/AC mains operation.

The eight pins are equi-spaced around the pin circle and location into the valve holder is aided by the metal skirt. This valve is not special in its performance.

In general, TV sets using a series heater chain had to use 0.3 Amp 'P' series valves so that the total voltage of the heater chain (17 valves, say, plus tube) was less than around 170 V. This was to allow operation from 200/210 V mains after making an allowance for voltage drop in a series surge limiting resistor.

'U' series valves such as the UBC41 and UABC80 had 0.1 Amp series heaters and were intended for use in domestic radios (etc.) where only 4 or 5 valves are required so the heater voltage drop per valve can be greater.

The number of equivalents suggests that this was a standard type.

The thin glass tube envelope is 20 mm in diameter and, excluding the B8A base pins, is 55 mm tall.

References: Data-sheet & ¹⁰⁴⁰. Type UBC41 was first introduced in 1949. See also 1949 adverts.

Pin Connections

Absolute Maximum Operating Conditions^¶

Thanks to Frank Philipse for supplying the above PDF datasheet.