Testing Germanium PNP for leakage? I'm confused...still.

[blearyeyes]

Chinese Transistor tester says:

hFE=   50.7
Ic=.     .59mA
UBE=   66mv
ICE0=  .63uA
ICEs=  11uA

That is in Chinese I think?
Is the Ic reading leakage?  Current / Collector = .59mA ?
I'm on the edge of setting up to do old school RG KEEN on a breadboard to figure out what is what...
unless you would be so kind as to tell me if there is a leakage reading or a calculation from that data in there?

[jessenator]

I tried doing the Keen method and got confused to the point where I look at the spec for the transistor and if it falls within that range, I just use it—not scientific, not best practices, I'll grant.

My tester which does Ge doesn't even show all the specs of what you've got, and my T7 won't do Ge at all.

This post on audiokarma goes into some detail about different types of testers. The Peak Atlas, of course, are the most thorough when it comes to transistors.

Although if yours is showing more, maybe the leakage current is accurate, at least for our purposes—someone on DIYSB laid it out:
ICE is indeed collector-emitter leakage (I=current, C=collector, E=emitter)
"o" (0?) means base is open
"s" means base is shorted

[blearyeyes]

I just re-read the instructions and I spent hours doing it all wrong.. HA! I guess I better dig out the ones in the trash… PITA

1. Measure leakage: With one end of the 2.2m resistor disconnected and your multimeter set to 20v or 2v DC let the transistor stabilize* before noting down the reading you get. When you feel the transistor has stabilized and you've got a reading you think reasonably accurate compare it with the following guide:

0.137v = 50 uA / 0.05 mA
0.274v = 100 uA / 0.10 mA
0.548v = 200 uA / 0.20 mA
0.822v = 300 uA / 0.30 mA
1.096v = 400 uA / 0.40 mA
1.37v = 500 uA / 0.50 mA

N.B. uA = microamps and mA = milliamps (1000 uA = 1 mA).

E.g. A reading of 0.115v = a leakage of < 0.05mA

According to RG Keen transistors that are <0.30 mA are The Good; those that hit or exceed 0.50 mA are The Bad; those that greatly exceed 0.50 mA would be The Ugly I think.

2. Measure the nominal Hfe: connect the 2.2m resistor and, when you're happy the transistor has stabilized, note down the reading you now get and multiply this by 100. E.g. 1.89v = 189 Hfe.

3. Now the correct Hfe: subtract the reading for leakage from the reading for nominal hfe and multiply the result by 100. E.g. 1.89v - 0.115v = 1.775. 1.775 x 100 = 177.5 Hfe.

[blearyeyes]

As far as matching them to the spec sheet.....

[blearyeyes]

I tried doing the Keen method and got confused to the point where I look at the spec for the transistor and if it falls within that range, I just use it—not scientific, not best practices, I'll grant.

My tester which does Ge doesn't even show all the specs of what you've got, and my T7 won't do Ge at all.

This post on audiokarma goes into some detail about different types of testers. The Peak Atlas, of course, are the most thorough when it comes to transistors.

Although if yours is showing more, maybe the leakage current is accurate, at least for our purposes—someone on DIYSB laid it out:
ICE is indeed collector-emitter leakage (I=current, C=collector, E=emitter)
"o" (0?) means base is open
"s" means base is shorted

just speculation but maybe the confusion is caused by different results due to different conditions. My little transistor tester is running under 5v but Keen's setup is exactly at 9v using my linear power supply. Wouldn't that affect the leakage? Both Keen's and Tran tester get the hFE very close.

[Bret608]

Yes, the gains and leakage can show up differently with even small changes in voltage. I built an RG Keen tester on vero, then grabbed duhvoodooman's Ge calculation spreadsheet off the BYOC forum. That way I was able to enter the exact resistor values from my vero on the spreadsheet. That way I didn't need to hunt down the oddly specific resistor value the Keen tester was calling for. I built both PNP and NPN testers, so then created tabs for each of those within the spreadsheet. I just hook the vero up to a battery, but I measure the battery every time so I can enter the exact voltage in that cell. Not an issue if you're using a regulated power supply, of course!