AF117 Transistor Data

Key transistor data for the AF117 germanium PNP high frequency (for its day) transistor including key electrical parameters, pinout, package type and many other key transistor details.

The AF117 was an RF transistor used in many radios and other applications where higher frequencies were needed. Although by today's standards it has a relatively poor performance, in its day, it was a great transistor.

The AF117 was a diffusion alloy transistor intended as AM broadcast mixer / oscillator.

The transistor was manufactured by a number of companies including Mullard, Philips and Siemens.

Key details and performance parameters for the AF117 transistor.

Transistor parameters & data
Parameters	Details
Transistor type	PNP germanium transistor
Package type	TO7
V_CBO max (V)	32
V_CEO max (V)	15
V_EBOmax (V)	2
I_C max (mA)	10
T_J Max °C	75
P_TOT mW	75
f_T min (MHz)	75
C_OB	3p
h_fe	50 min
I_C for h_fe	1 mA
Similar / equivalents	AF124

Outline:

Pinout:

Explanation of transistor parameters

Parameter	Explanation
V_CBO Max	Maximum collector-base voltage with emitter open circuit .
V_CEO Max	Maximum collector-emitter voltage with base open circuit.
V_EBO Max	Maximum emitter-base voltage with collector open circuit.
V_CEsat (included where applicable)	The voltage drop across the collector-emitter when the transistor is fully saturated (acting as a closed switch).
I_C Max	Maximum collector current.

Parameter	Explanation
T_J	Maximum junction temperature.
P_TOT Max	Maximum device dissipation normally in free air at 25°C unless other conditions indicated.
f_T Min	Minimum cutoff frequency at which the current gain in a common emitter circuit falls to unity.
C_OB Max	Maximum collector capacitane, normally measured with emitter open circuit.
h_FE	DC current gain for H_FE at I_C. [Note hfe is the small signal gain and although this may be slightly different, the transistor current gain will vary considerably from ne transistor to the next of the same type.]
P_TOT Max	Maximum device dissipation normally in free air at 25°C unless other conditions indicated.

These are the main transistor parameers that have been included in our list. There are others, but these help quantify the main elements of the performance of the transistor.

Read more about . . . . Transistor Data-sheet Specifications & Parameters.

Please note, that the data given is the best estimate we can give within a tabulated summary of this nature. Parameters also vary between manufacturers. Electronics Notes cannot accept any responsibility for errors, inaccuracies, etc, although we do endevaour to ensure the data is as accurate as possible.

Notes and supplementary information

These AF117 transistors and similar ones in the series have proved to be unreliable in the long term. They are a common cause of failure in vintage transistor radios.

They tend to develop internal short-circuits between the can and either the collector or emitter. Sometimes it is possible to tap the device sharply at which point it might possible crackle or come to life.

It appears that the cause is that minute hair-like conductive strands grow over time and these can cause short circuits within the encapsulation of the device.

Often it is possible to replace them with an NPN silicon equivalent - sometimes it will be necessary to change the bias, other times this may not be needed.