Collins Aerospace Museum

233D Transmitter Restoration Project

I expect that the work Jules has done on the old shaft will make things work a lot better. I expect that the channels that appeared to be repeatable didn’t have many reversals involved; should be fun to do more detailed observations. Thanks, Jules for the quick work. That should really help.

I’ve quite of lot listening on 7290 and 7295 for the last several days. Lots of AM on both frequencies, but 7290 seems to have more activity. Guess I also like being further from the band edge. So that will be the initial frequency we will try to get crystaled up on. I am assuming we will be using 3645 and then doubling to the operational frequency.

I’ve got most of the mechanical work done on the 6ag7 crystal test jig. Problem is that the socket that I thought would allow the holders to plug in is too small. Since we have 10 sockets on the exciter, I’ll just plan to use the 837 on that chassis as the test jig. Likely the socket capacitance on the exciter will be different than a single socket or something fab’d. I’ll go ahead and finish the test jig and use “standard” sockets to verify activity and frequency on “donor” crystals.

Doubt if I’ll make it on Wednesday during the museum opening hours. Have something scheduled at 11A that may last for 2 hours.


Hi folks, Wednesday of this week I installed the original shafts and couplers between the autotune motor and the exciter assembly. This just involved replacing missing set screws and aligning the shafts properly so that the autotune system will be functional with the exciter unit. During the upcoming week I shall go to the Granger facility and procure the new couplings plus two coller units and a length of 11/32 inch shaft rod to replace the missing hardware between the exciter unit and the RF final assembly plus antenna tuning assembly. At this point we will have to get Don Grimm to provide the machining of these shaft for completion of the entire autotune system. It has already been demonstrated via Jim Jones that the autotune system is working properly with the exciter assembly and all we have to do now is to align the autotune dial assemblies of both of the RF final and antenna tuning units to mechanically track with the exciter autotune dial assembly. This should complete this part of the restoration. Jim Rod and Mike have done a terrific job in getting all this put together. Hopefully soon the entire system will be fired up for contacts over the air.