The 39/44 pentode follows the pattern for RF valves. The control grid g1 is taken to the top cap to minimise the interaction between the grid and anode circuits. The anode ac resistance of 1M Ohms clearly shows the high impedance circuits that it would be used in. As it is not of the variable μ type it could not be controlled with AGC (Automatic Gain Control) derived from a rectified signal.

The classic envelope is 37 mm in diameter and, excluding the UX5 base pins, is 100 mm tall.

 
Pin Connections

UX5	1	2	3	4	5	tc
	h	a	g2	k	h	g1

 
Absolute Maximum Operating Conditions

Pentode	Vh	Ah	Va	Vs	Vg	mAa	mAs	ra	gm
	6.3	0.3	250	90	-3	5.8	1.4	1.0M	1.1

This exhibit was last updated on 02 July 2002