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Parameters for an acceptable germanium transistor

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Forum » Valves / tubes - Semiconductors » Semiconductors » Parameters for an acceptable germanium transistor
           
Omer Suleimanagich
Omer Suleimanagich
 
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07.Oct.17 22:24

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From all the research I have done, many conclude that germanium transistors should only be used if their measured leakage is less than 300uA or 0.300 mA

Can anyone on RMorg confirm this?

Michael Watterson
 
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08.Oct.17 17:43

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It depends on the test temperature, test voltage, if base is open or connected to emitter and the exact device. They are very temperature sensitive and very voltage sensitive.

Leakage is more important for signal devices than power devices. You need to examine the circuit it's used in and the device data to decide if the leakage is a problem.

I would test with base connected to emitter, 3V supply (or half the application HT voltage) and at 20 degrees C or less. A hot climate will give high readings.

Certainly at 20 C and 3V, with base to emitter, the 300uA might be far too high unless it's a power device. At 30 C and 20V, the 300uA might be misleading.

Omer Suleimanagich
Omer Suleimanagich
 
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08.Oct.17 20:54

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So in practicality, what you are saying is, power germanium transistors can be leaky (above 300uA) in an amplifier circuit

 

What about germanium transistors used in the IF, RF, or predriver sections of an FM?

Michael Watterson
 
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08.Oct.17 22:43

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Even 300uA might be far too high.

You need to measure at 20 degrees C and 3V or at worst 1/2 the HT voltage. In that case I'd expect very much less than 100uA, but leakage can be very high at higher temperatures and/or higher voltages. Consult the data sheets.

Omer Suleimanagich
Omer Suleimanagich
 
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09.Oct.17 05:36

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Actually, I am using one of these, 

PEAK Atlas IT (DCA Pro) ADVANCED SEMICONDUCTOR ANALYZER with Curve Tracing

  
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