Together with some friends, we have managed to get our hands on some ancient (1997) Motorola Dimetra TETRA equipment. Specifically, this includes the Base Radios (BR) and the TETRA Site Controller (TSC).
We haven't yet managed to put everything up in the wiki, but you can watch our progress at the Dimetra_EBTS page on http://tetra.osmocom.org/ as well as it's sub-pages.
It's going to be a big challenge to put all that equipment to some good use. Success is probably defined in terms of running your own small TETRA network with such an EBTS but without any of the Motorola Dimetra core network infrastructure (SwMI, basically the same thing we did for GSM with OpenBSC.
The big conceptual difference to GSM here is: In GSM, the internal protocols (A-bis, A, ...) are all publicly specified. There are vendor-specific dialects, but those are relatively easy to figure out. In TETRA, the ETSI only specified the air interface, but not the interfaces between the wired components of the network. This leaves pretty much everything else proprietary :(
So if anyone has any information (installation manuals, service manuals, provisioning software, protocol specifications, ...) or experience with configuring or maintaingin this equipment, I would be very happy if you could drop me a message.