Portable Precision Laboratory A-100, X-100

This is a kit of four small instruments intended to enable a service technician to troubleshoot problems in the field, especially televisions, by injecting signals at strategic locations (model 103 signal generator and model 104 synchro-sweep generator), making critical measurements (model 102 high voltage meter), and passive components to temporarily replace suspected faulty resistors, capacitors, potentiometers, and speaker (model 101 substitution tester).  The four items could be purchased separately, or together as a kit of four separable modules in a wooden carrying case (A-100) or as four modules permaently combined into a single case (X-100).  The photo is of an A-100 model.  The intent was to reduce the need to bring faulty sets back to the repair shop for diagnosis.  

Price for the A-100 with wooden carrying case and all four instruments, individually removable, was $122.40.

Price for the X-100 with wooden carrying case and all four instruments, permanently mounted, was $112.00.

Here you find 5 models, 5 with images and 2 with schematics for wireless sets etc. In French: TSF for Télégraphie sans fil.
All listed radios etc. from OR - Oak Ridge Products - Video Television, Inc.; Long Island City (NY)