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KSA992F Question about matching

Clark Leach

Clark Leach

New Member
I'm preparing an order which includes the KSA992F and I'm wondering how many I should order to ensure I can find a matched pair. Also, if you could point me in the direction of how to go about matching them, that would be helpful.
 
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DIY Transistor Matching Circuit
You can use your meter to compare Vbe if it has a diode test range. One of the cheap Chinese component testers from the 'bay can be used.
If you are matching for dc offset in a power amp output you can just try some 'in circuit' testing. For that purpose Vbe is the first spec to match, then gain (hFE).
I buy small signal transistors in 100 lots for price break, but I build hobby things so extras 'in stock' are a benefit for me.
 
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Clark Leach said:
I'm preparing an order which includes the KSA992F and I'm wondering how many I should order to ensure I can find a matched pair. Also, if you could point me in the direction of how to go about matching them, that would be helpful.
Click to expand...

In my experience, transistors from the same lot are usually very close in both Vbe and Hfe. Close enough to get good results in differential pair, which is what I am guessing you are wanting to do.

That said, they are cheap and handy...buy 20 or 30. You'll get some pretty much perfect matches, no problem.
 
Fyi

My 992 and 1845 gain matching did find 4 pairs, in a sample size of 40.
Btw. Some were 10 points delta, but I was able to get 4 within one point of each other.

Remember, temperature of the part does affect the values .

Best of luck.
 
Connect up a transistor, let it sit for a couple minutes on your tester and then test it. Record the reading. (Ambient temp). Then clamp the transistor between your finger and thumb, testing after 30 seconds, 1 minute, 2 minutes. The readings will change on temp.

Best is to connect the tester to the transistor, wait a couple minutes for the transistor to stabilize and take the reading. Then set up the next one. Time consuming? Sure, but you'll get good matches. I've found that Transistors on ammo packs or tape loading tend to test tighter than bulk transistors.
 
Clark Leach said:
I'm preparing an order which includes the KSA992F and I'm wondering how many I should order to ensure I can find a matched pair. Also, if you could point me in the direction of how to go about matching them, that would be helpful.
Click to expand...
I usually will get 20 or so pieces.
I'd get the KSA992FBTA -- Higher gain..
FB Hfe 430-600
F ---Hfe 300-600
https://www.mouser.com/ProductDetail/onsemi-Fairchild/KSA992FBTA?qs=/ha2pyFadugHMYk8M8xnZvF7TeqjvWdc1AI1mBvBMSkEMOTclwLhQw==
 
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Btw,
The low cost component testers available on Zon and Pbay will suffice for this task.

Less than 30.00 and worth it.
 
larryderouin said:
Connect up a transistor, let it sit for a couple minutes on your tester and then test it. Record the reading. (Ambient temp). Then clamp the transistor between your finger and thumb, testing after 30 seconds, 1 minute, 2 minutes. The readings will change on temp.

Best is to connect the tester to the transistor, wait a couple minutes for the transistor to stabilize and take the reading. Then set up the next one. Time consuming? Sure, but you'll get good matches. I've found that Transistors on ammo packs or tape loading tend to test tighter than bulk transistors.
Click to expand...
Apart from this, and despite the glue, the ones on tape enable to write down the figures and they stay with the item!:thumbsup:
 
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