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 170V. This was to allow operation from 200/210V 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.

 
Pin Connections

B8A	1	2	3	4	5	6	7	8
	h	a	g	s	ad(2)	ad(1)	k	h

 
Absolute Maximum Operating Conditions

Triode	Vh	Ah	Va	Vg	mAa	ra	gm
	14	0.1	170	-1.6	1.5	42k	1.65

Thanks to Frank Philipse for supplying the above datasheet

This exhibit was last updated on 12 June 2007 {find valves by name}