The UBF80 features a variable μ amplifier pentode and a pair of diodes in screened envelope. This suggests use as a final IF amplifier with the diodes for signal and AGC rectification. The 100 mA heater requirement was to allow for operation in receivers without mains transformers, the so called universal sets as they could operate from DC mains as well as AC.

The valve in close-up shows that he grids are visible through a hole in the screen and anode.

The thin glass tube envelope is 20 mm in diameter, and excluding the B9A base pins is 55 mm tall.

 
Pin Connections

B9A	1	2	3	4	5	6	7	8	9
	g2	g1	k,s	h	h	a	a(d1)	a(d2)	g3

 
Absolute Maximum Operating Conditions

Pentode	Vh	Ah	Va	Vs	Vg	mAa	mAs	ra	gm
	17.0	0.1	170	85	-2.0	5.0	1.75	1M	2.2

Thanks to Frank Philipse for supplying the above PDF datasheet

 

This exhibit was last updated on 12 June 2007