To quote from the Tektronix catalog, the TM 506A mainframe accepts up to six different TM-500 series plug-ins providing a complete test station with one power cord. The right-hand compartment is a high-power compartment. Forced air cooling is standard. The mainframe may be fitted with the optional rear interfacing kit (Option 002), however none of the mainframes we have on offer are so optioned.
The mainframes have been tested and found to be functional. The 506A version is the newest of the TM-500 mainframes. It is similar to the TM-506 non-A with the addition of a grill extension (similar to the TM-5006) – this allows some cable dress to be done inside the housing. The mainframes are in superb cosmetic condition as well.