Thanks Fred, Steve, Tom:

I think you guys are correct about these being house
numbered devices. They are from an old Piper autopilot
that was manufactured for Piper by Mitchell Industries
of Mineral Wells, TX (now Century Flight Systems).
I noticed that 2 of the 12 power transistors had
been replaced at some point in time and are marked
with "Mitchell Industries MN92". Since this was an
avionics application, it is likely that these were marked
specifically for Mitchell, initially with the 48S23 device
number and then later with Mitchell's name and MN92
marking.

I've made an attempt to see what information Centrury
Flight Systems is able and/or willing to provide, but so
far they have not been too responsive. I'm also looking
for a spare amplifier from the aircraft salvage yards and
avionics shops.

My main interest in all of this was to generate a schematic
of the amplifier and do a bit of reverse engineering in order
to better understand the overall design of the system. The
service manual for the autopilot system did not include a
schematic or any details of the amplifier.

Thanks again for the help.

Ronnie


"K7ITM" wrote in message
oups.com...
As Fred and Steve noted, you have a bunch of "house-numbered"
transistors, and one that's relatively easy. Actually, the MA900 seems
to be from a series of germanium parts. I have numbers on both sides
of it, but not that particular one, in my book. I do have a full
Motorola data sheet on the 2N1192, in my 1969 Motorola "Semiconductor
Data Book." Since I'm about to scan something else, I scanned it into
a PDF (as images, not text). It's not great, but it's legible. Email
me if you'd like a copy.

Cheers,
Tom