from FB group Building Transistor Radios 2018-08-22
Olek Kopyto
I recently did some tests on 2N3904s I got from Mouser and from a Chinese eBay seller. The ones from Mouser had a current gain of right around 200, right in the middle of the 100 to 300 gain range according to the data sheet. The Chinese were all 300 or more, some as high as 390. This is out of range, and it doesn’t seem to be as bad as if it was too low. But if a circuit is designed for below 300, using one with higher than 300 could cause stability issues such as oscillation or instability.