TO Case BJT NPN Transistor Values

[Robbie010]

Hi All,

Back again for more help with my amplifier project.

My component tester arrived today so I pulled one of the TO output transistors.

It came back as a BJT NPN transistors with the following values:

hFE = 44
Ube = 676mV
Ic - 6.0mA

536mV between Emitter & Collector

As I am overhauling and upgrading the amplifier I will be looking to replace these with new so could somebody please tell me what these numbers mean in laymans terms and what values I should be looking for in a replacement part?

Thank you!

[Benta]

They mean nothing, except that your part is probably OK. Finding maximum collector voltage or maximum power is futile.

[Kleinstein]

hFE should be the current gain. The value of 44 is about normal for a power transistor.
Ube should be the base to emitter voltage. The value indicates a single transistor (no Darlington). One might need to readjust the standing current if much different.
Ic and the emitter to collector voltage should be just the operating point. Though only 540 mV would be rather low, but too much for saturation voltage at the usually low test current.  So this does not provide much confidence in the numbers.

For a replacement it is more about maximum voltage, SOA curve and maybe transit-frequency. So looking for a replacement more starts from the original part number and the circuit.

[Robbie010]

Thank you.

Unfortunately, there are no markings at all on the body of the transistors, so I'm out of luck there......

I am in the middle of trying to draw up a schematic for the amplifier so I'll see where that leads me.

 

[Doctorandus_P]

I tried to copy and paste Wikipedia here but it won't let me because of a 5000 character limit.
So I'll drop a link instead.
https://en.wikipedia.org/wiki/Bipolar_junction_transistor