The N309 was designed as a sensitive video output valve for television receivers and is the equivalent to the Mullard PL83.

The N153 is very similar but has a higher ra value.

The valve is also rated for service as an audio output device. With 68 Ohms in the cathode lead to generate grid bias, and a load impedance of 5000 Ohms the N309 will give 1.65 Watts at 7.8% total distortion. With the high gm value it will need little drive.

The marconi label is a brand name of the M-OV company.

The thin glass tube envelope is 20 mm in diameter, and excluding the B9A base pins, is 68 mm tall.

 
Pin Connections

B9A	1	2	3	4	5	6	7	8	9
	g2	g1	k	h	h	g3	a	s	-

 
Absolute Maximum Operating Conditions

Pentode	Vh	Ah	Va	Vs	Vg	mAs	ra	gm
	15	0.3	170	170	-2.5,mAa_32.0	4.2	41000M	10.0

Thanks to Frank Philipse for supplying the above datasheet

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