The type 27 triode is also known as the UY-227 as in this exhibit. It is an indirectly heated audio valve with a good reputation for performance.

With 90 Volts on the anode the grid bias should be -4.5 Volts. At 135 Volts on the anode the bias should be -9 Volts. At the absolute maximum anode voltage of 180 Volts the bias should be set to -13.5 volts. The heater cathode voltage should not exceed 9 Volts.

The anode is a mesh and the supports are substantial rods.

Seen straight on the two mesh anode plates are fixed together by notching. The grid support is on one side of the grid only.

The close-up on the base of the anode shows the cathode cylinder, heater wires and control grid.

The balloon envelope is 42 mm in diameter, and excluding the UX5 base pins is 96 mm tall.

 
Pin Connections

UX5	1	2	3	4	5
	h	k	g1	a	h

 
Absolute Maximum Operating Conditions

Triode	Vh	Ah	Va
	2.5	1.75	180

Thanks to Frank Philipse for supplying the above datasheet

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