These are made by Instrument Associates Inc. (IAI) as the OEM using GP300 radios as the RF portion and marketed as Motorola "Synthesized RF Link." Instrument Associates was bought out by GAI-Tronics Corp. Reading, PA. 1-800 492-1212.
IAI has been OEM'ing a number of products since around 1990. Their claims to fame are the DGT-9000 remotes for Spectra consolettes, the T-5600, the MRTI units and tone remote adapters for Maxtracs & GM300s and those junky newer tone remotes that have the solder jumpers and the membrane keypad.
This particular item uses a 68-82447W01 manual for it.
Part numbers are as follows:
Basic Model - just the strip in a minibox - no power supply or NEMA box -keep in mind the strip is a transceiver, not just a transmitter or receiver. VHF - L1744 UHF - L1745 Package Model - Power supply plus NEMA box and one strip VHF - L1746 UHF - L1747 Duplex Package Model - Power supply plus NEMA box and two strips, one with a fan VHF - L1928 UHF - L1748 Continuous Duty Operation Option E991 (has a fan) Omit Housing E876 N Connector (rather than SO-239) E877 NEMA 3 Housing E878 Rack mount E882 Omit Duplexer E883 RSS HVN9128A Cable TDN9782 Modems 1200 Baud TDN8352 2400 Baud TDN8511 9600 Baud TDN8503 DB15 Adapter kit (a DB15 male connector and photo-copied instructions for a nice mark up) TDN9781
The programming cable for these units is the same idea as the GP300 Cable with a couple of modifications. The GROUND pin goes to chassis ground of the unit, the BUS+ goes to PIN 7 of the DB15 on the unit.