CK722 germanium PNP transistor pinout

The CK722 is a vintage germanium PNP junction transistor for small-signal audio and low-frequency radio circuits.

Plastic and glass, three leads

3 contacts Current package

Raytheon · Flexible tinned leads on 0.08-inch centers.

Plastic and glass, three leads pinout

Plastic and glass, three leads

Map read from the red-dot end of the lead row: C (1), B (2), E (3).

Selected pin details

2 · B

Input · Inputs

Base. Pull it below the emitter through a resistor to bias the PNP junction.

Raytheon Transistor Applications, CK722 technical information, p. 110

Electrical limits · Link to this pin

All 3 pins

Pin	Signal	Direction	Function
1	C Collector	Collector	Collector. The red dot identifies this end of the lead row.
2	B Input	Input	Base. Pull it below the emitter through a resistor to bias the PNP junction.
3	E Emitter	Emitter	Emitter. It is the most positive terminal in the common-emitter fixture.

Signal assignments

Common emitter

Reference the base and collector voltages to the positive emitter. Germanium leakage and gain vary between parts and with temperature.

Electrical limits

Parameter	Limit	Conditions and source
Collector dissipation30 mW	30 mW	Tentative ratings in the contemporary Raytheon reprint at 30 °C. Raytheon Transistor Applications, CK722 technical information, Table 1, early application article
Collector voltage in test3 V maximum magnitude	3 V maximum magnitude	Fixture bound from its 3 V source. The collector is never driven above the emitter. Raytheon Transistor Applications, CK722 technical information, collector characteristics, p. 111
Collector current in test0.30 mA maximum	0.30 mA maximum	Fixture bound of 3 V divided by the 10 kΩ collector resistor. Raytheon Transistor Applications, CK722 technical information, collector characteristics, p. 111

Models and documents

The map covers the plastic-and-glass case with a red collector dot in Raytheon’s technical sheet. Match later metal-case devices to their own physical drawing.

CK722: Raytheon plastic-and-glass package in the technical information sheet.

Raytheon Transistor Applications, CK722 technical information· Manufacturer publication scanned in the MIT course archive. See pp. 110–111 and the early article with the CK722 tentative ratings.
Source register· Document revisions, applicable order codes, consulted sections and available file checksums.