Sensibly equivalent¶ to:
The N309 was designed as a sensitive video output valve for television receivers and was released in 1953. It 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.
References: Datasheet & 1040. Type N309 was first introduced in 1953.
Absolute Maximum Operating Conditions¶
Updated January 29, 2013. shape:thin.glass.tube construction:all.glass type:pentode age:1950.1960 base:b9a heater:300ma pins:9 pin:1.g2 pin:2.g1 pin:3.k pin:4.h pin:5.h pin:6.g3 pin:7.a pin:8.s pin:9.-