3g57, chick0n,
Could you take as much possibe high resolution pictures of the TG module pcb-s while you are working on it? I have multiple R3267 and R3273 units (it is one of my obsessions), but none of them has the tracking generator. I am thinking about making one myself (it is not something impossible at all). The key is, if I/we can decipher the paralel bus connection and communication to the main circuit board. Since I do not have one unit with TG, I cannot do this, but maybe if you will help (and maybe other forum members too), it can be done.
What I conclued from your pictures: On the control board the U20, is probably a Lattice CPLD used for paralel BUS to serial conversion. The U4, U6, U21, U22 are the bus transceivers and glue logic between the bus and the Lattice chip. The U7 (25C16) should be the EEPROM for the calibration coefficients. To get its exact content will be very important. It is an SPI EEPROM, the interface (the Lattice CPLD) between the SPI and paralel BUS of the M68K system is made similarly as in the case of the RF module.
In one of my units, which has option 21, I noticed that the preicsion OCXO is installed in a similar enclosure as the TG module (obviously, it is missing the upper RF part). But it seems, that the bottom control board should be similarly. The programming of the AD9850 can be made probably using the same SPI serial interface. I will disassembly the option 21 module, maybe I will be lucky, and it has a complete control board (maybe almost identical with the TG control board). This also means, that the TG and the option 21 cannot be used in the same time.
BR, Gyorgy