SPS2306 vintage transistor replacement

[gkmaia]

I am struggling hard to find a data sheet for a SPS2306 (M176) NPN signal transistor.

Closest reference cross I found was this one.

https://vetco.net/products/2n3904-bc547-pn2222-2n4401-npn-transistor-nte123ap

It is for Q11/12 on the schematics bellow.

[vk6zgo]

I am struggling hard to find a data sheet for a SPS2306 (M176) NPN signal transistor.

Closest reference cross I found was this one.

https://vetco.net/products/2n3904-bc547-pn2222-2n4401-npn-transistor-nte123ap

It is for Q11/12 on the schematics bellow.

I have found equivalents lists of little use, & fall back on other means.

An old trick is to check whether the equipment uses the same device elsewhere in a "non critical" role.
If so, you can probably steal that one & get a "jelly bean" device for the "donor" spot.

Another idea is to have a look around to find out what device other manufacturers use in a similar position.
The old "What does Philips/Sony/whoever do?" trick.

[duak]

I see that Q11/Q12 are used as back to back zener diodes to clamp the voltage to +/-7 V or so.  I have seen the 2N4401 used for this purpose more than any other device but I can't say why; maybe because it is rated for 600 mA.

Here's a link to National Semi's 1971 transistor data book.  It's surprising how many devices with different numbers use the same die.

[Benta]

SPS transistor numbers were very often custom stamped Motorola types back then. Could be almost anything, you'll need to find an old Motorola Small Signal databook.

[gkmaia]

thanks for the old databook tip. I think I found it.

[critchy87]

Hi I’m actually looking to replace same transistor sps2306 on a b&k 467 pcb. Did you ever find an equivalent or something that will work?

Thanks
William