Ooo... What is that?

Octafish

My brother was chucking a load of old junk including an old 60s Bush radio which I took to have a see what's inside.....

Feel the mojo.... a Mullard OC71 !

https://i.imgur.com/4rwiz1T.jpg

https://i.imgur.com/O4Ea3CN.jpg

I've pulled it along with an AC128 that was in there. The OC71 has low leakage (0.149) and good hFE (63.1). Might have to try it in my Hudson Broadcast build

Gagaryn

Yup, I have my mothers old Bush (radio!) which also has OC71 in it, they were pretty common in transistor radios. My plan is to fit a DAB in it but so far all I've done with it is wire a 1/4 inch jack in and use it as a small portable amp. Sounds rubbish but in an amusing way!

lewism

I don’t think the AC128 will be original but those types of radio normally have an OC44, two OC45, an OC71, an OC81d and two OC81 - trouble is, it’s an absolute crapshoot as to whether they’ll be useful in terms of gain and leakage. You also see lots of weird and wonderful substitutions.

Octafish

lewism said:

I don’t think the AC128 will be original but those types of radio normally have an OC44, two OC45, an OC71, an OC81d and two OC81 - trouble is, it’s an absolute crapshoot as to whether they’ll be useful in terms of gain and leakage. You also see lots of weird and wonderful substitutions.

No OC's apart from the OC71 (which has low leakage and good gain), a load of four leg AF117s though. The AC128 has low leakage, but just 32hFE. Maybe it's a replacement although the solder looked untouched and it's the old style can without the flared skirt.