I bought some bf494's on eBay and tested the hfe.

I used one of those simple component tester also bought here.

Earlier tests indicated that this device gives a very good indication.

The 10 bf494' had hfe's between 390 and 432.

Several datasheet mentions hfe's of max. 222.

My theory is that they used some cheap audio transistor with medium hfe and sell it as bf494.

Can someone help me out?

Ron Werner
Norway

 

Hello,

Could it be that the transistor is a BF494A?
That has a HFE range from 200 to 500.

Bertus

 

This datasheet is no longer available on the producers website as far as I can see.

I sent a request for information, but don't expect an answer.

I guess I will just have to put these devises to the test.

An old NXP bf494 had an hfe of 167.

Thanks,

Ron Werner
Norway