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The UCH42 is an early all glass triode hexode from 1948 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 ECH42 does the same job but with higher anode voltages and lower current.

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

The valve is marked with the Mullard logo and was made in Holland by the parent company Philips.

The overseas origin is clear but this exhibit does not have the pejorative Foreign added to it.

Through the end wall in the screen can be seen the wire grids and lower down the strap the connects the two small plates that form the anode. The locating pip is moulded into the glass and no metal skirt is needed.

The thin glass tube envelope is 21 mm in diameter and, excluding the B8A base pins, is 53 mm tall.

References: Data-sheet & ¹⁰⁴⁰. Type UCH42 was first introduced in 1948. See also 1948 adverts.

Pin Connections

Absolute Maximum Operating Conditions^¶

Absolute Maximum Operating Conditions^¶

Thanks to Frank Philipse for supplying the above PDF datasheet.