GT703G=AD150=NTE121

Can a GT703G germanium transistor be used to replace an AD150?

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Under some circumstances it may be possible to replace the AD150 with gt703g. The max voltage and consumption are nearly the same, except the max power dissipation (30 W vs. 15 W). In power push pull stages it's necessary to use a pair of equal types and to adjust carefully the quiescent current about 20...30 minutes.

 

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My main question here, is the "transitional frequency" of 10,000 hz of the GT703G and 450 khz of the AD150    Would this create any problems or distortion?

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the gt703g can be used for "simple" amplifiers or power switches with a f t of less than 10 kc - and isn't recommended for full audio range amplifications, such as medium / high class hi-fi stereo amplifiers / units. For latter reasons a AD150 or similar type should be used. Some offers I have seen on E*ay these days. Another option may be the SFT213 or 2N1536 instead.

 

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So what you are saying , if I understand correctly, is that the GT703G is

not able to amplify sound frequencies over 10,000 Hz?

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You mentioned in post #3 the f t of 10,000 kc - I myself don't have datasheets with this limitation. The f t value says, that an amplification factor of 1 (!) at this frequency will be guaranteed. The less the frequency is, the more amplication will be possible, up to the named values (beta/hfe). If the limit of 50,000 kc of gt703 is true (I don't remember the source...) then this transistor may be used in stereo amplifiers, too.

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Here is the data for the GT703G Type Designator: GT703G Material of Transistor: Ge Polarity: PNP Maximum Collector Power Dissipation (Pc): 15 W Maximum Collector-Emitter Voltage |Vce|: 35 V Maximum Collector Current |Ic max|: 3.5 A Max. Operating Junction Temperature (Tj): 85 °C Transition Frequency (ft): 0.01 MHz Forward Current Transfer Ratio (hFE), MIN: 50 Noise Figure, dB: -

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Thank you for this information / confirmation - so my response to post #5 is: YES
 

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