Rokreder

That is a good point on the model number, the dataplate has fallen off so I don't actually know. I have reverse engineered my unit, and it is exactly as expected based on pictures I found and what you've previously told. This is the setup, repeated once per axis (antenna is where the sphere connects, TX is the synchro board you've been working on): On the main connector we supply 115VAC power and the stator signals S1-3 for each of the axes. (As well as control voltages for flags and 5V for red/white backlight) The backpack only contains the amplifiers (triangles in figure), that take the error measured from the control transformers (CT) and drives AC servomotors (ø1 26VAC). The motors also contain tachometers that the amplifier would use to control motor speed. And that's really all there is too it.* The motors shouldn't be too hard to drive, and since I have raw access to the synchros I think I can simplify/cheat a fair bit. Still very interested in following your progress on the proper way of emulating synchros, as I have other avionics modules where I know that will be required. You probably knew a lot of this already, but hopefully this was at least interesting for other people reading the thread * The adjust knob on the front puzzles me a bit still. Some of the signals go to what appears to be a potentiometer in the sphere, but I do not (yet) dare take it far enough apart to see what's going on

I lucked out and was able to grab one for cheap off eBay 2 weeks ago, along with a matching horisontal situation indicator. I believe them to be from an F-111 Aardvark, though it is not a 100% exact match. Crucially, THE PINOUT IS DIFFERENT As it was missing the amplifier backpack, I cracked it open and started reverse engineering. And I quickly realised that it didn't match the ARU-11/A pinout description I had found on the web here. For example, the page lists A and B as 115V 400Hz supply, but in my unit, these pins connect to the glideslope indicator... which was missing, maybe because the previous owner applied 115V? So just to be safe @richfiles, do a little sanity check before you apply power to your unit(s). A multimeter in diode test mode allows you to move most flags and indicator bars when touching the right pins. If they are connected where your pinout tells you they should be I think you are good.