Collins Aerospace Museum

Mar-28 ···
233D Transmitter Restoration Project

The Autotune® motor is one of the components requiring three-phase power to operate. Doing so, made it convenient to reverse the motor’s rotation - just swap any of the three phases...
Lawrence and Jules came to lunch today and we had a great discussion about the 233D and other world problems.

Jules and I got started chasing some systems connect issues and I think we learned quite a lot. Good to have him back on the project.

The RF bay cleanup is coming along nicely. I expect to reinstall the final PA deck and Grid circuit deck next week. I should also have the PA filament supply complete next week, so I can reinstall that and see if we have can light the filaments on the finals as soon as we can get 230 single phase available. Lighting the filaments is a pretty small step, but it should be a heartwarming experience for us old guys. And it will provide some needed wiring checkout.

The 68N-2 HV relay is nowhere to be found. I had thought it was the relay on the PA filament chassis, but that does not appear to be the case. I have a call to Brian, the previous owner, to see if he remembers it. Will also ask about the Autotune shaft and the RF cabinet blower. None of the three are likely show stoppers, but they will all require some level of effort to replace.

Looked at the 406B-1 Audio power supply (Unit CE) chassis from the Mod Bay because it was easy. The bleeder resistor (another wire-wound) appears to be open. Schematic does not agree with as wired. Schematic shows a filament transformer for the 173 tone control chassis that isn’t present on the power supply. Possible the transformer has an additional winding so that might not be a problem. Filter caps may need to be replaced. Chromed chassis is pitted, but we can likely just clean it up.

There are 26 transformers connected to the single phase 230 primary circuit, so that is a major concern. 2 or 3 are showing some evidence of oil leaking, so we may have to be prepared to replace or rewind them. Every primary is fused, so that should help somewhat.

There is a “mystery” three phase input transformer that is likely used to supply the 813 plates on the exciter, but I haven’t found any reference in the parts list or on the schematics. It was strapped to the pallet with the Mod transformer and the big plate transformer, but I haven’t found any space inside the three cabinets for it. Likely I’m missing the obvious.

Relay logic is going to be a challenge. We’ll likely need a gallon of De-Oxit to clean up the contacts.