The UCH42 is an early all glass triode hexode from 1949 and was designed as oscillator and mixer for superhet receivers, and the hexode section was designed to operate with an AGC control voltage. The 100 mA heater was intended for universal (AC/DC) sets, and this explains the low anode voltages. Mullard do not give a frequency range for this device, it is, therefore unlikely to be greater than HF as the valve predates VHF broadcasting by more than a decade. Mullard also say that the UCH42 may be used as a phase inverter.

The triode oscillator had to supply a peak to peak insertion voltage of 13 Volts.

Another Mullard UCH42 but this time made in Britain. The construction of the envelope is the same. We believe that equipment designed at Philips would be used in both the UK and Holland, as one would expect within a group of companies.

The locating pip is moulded into the glass skirt.

The thin glass tube envelope is 20 mm in diameter and, excluding the B8A base pins, is 51 mm tall.

 
Pin Connections

B8A	1	2	3	4	5	6	7	8
	h	a	a(t)	g(t),g3	g2,g4	g1	k	h

 
Absolute Maximum Operating Conditions

Hexode	Vh	Ah	Va	Vs	Vg	mAa	mAs	ra	gm
	14	0.1	200	85	-2	3	3	1M	0.75

Triode	Va	mAa
	100	3.1

Thanks to Frank Philipse for supplying the above datasheet

This exhibit was last updated on 07 June 2009