The 1R5 is a frequency changer heptode for a battery portable broadcast radio receiver. The heptode or pentagrid structure has two control grids g1 & g3 with screen grids held at RF ground at g2 & g4. G5 is the suppressor grid.

The valve would be made to self oscillate, and the intermediate frequency would be extracted from the tuned anode circuit. The oscillator would probably be generating 15 Volts peak to peak.

The thin glass tube envelope is 18 mm in diameter and, excluding the B7G base pins, is 46 mm tall.

 
Pin Connections

B7G	1	2	3	4	5	6	7
	f-	a	g2-g4	g1	f-	g3	f+

 
Absolute Maximum Operating Conditions

Heptode	Vh	Ah	Va	Vs	Vg	mAa	mAs	ra	gm
	1.4	0.05	90	45	-0	0.8	1.9	0.8M	0.25

Thanks to Frank Philipse for supplying the above datasheet

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