SFT 316 - GE trans with 4 pins

[KarenColumbo]

Guys, I just happened upon a single SFT 316 GE transistor at my local "I have it all" store. It has 4 pins. Why? Never suspected those three legged beauties to have an extra one ...

[amptramp]

The fourth connection may be to the metal shell of the transistor case.

[highwater]

Datasheet (sort-of): http://www.semicon-data.com/transistor/tc/sa/SFT316.html

TO44 package. According to this page, the middle pin is an "interlead shield", probably just to reduce parasitic capacitance. Might be intended to connect to ground, maybe the emitter, or maybe just left unconnected. Unconnected is the safer option, and the reduced capacitance (if that is the point) is probably irrelevant at audio frequencies.

[KarenColumbo]

thx guys - couldn't find any info on this one, you solved this particular riddle