ELECTRICAL SIGNAL PRODUCING APPARATUS, NAMELY, SIGNAL GENERATORS AND SIGNAL SOURCES, SOLID STATE AND ELECTRONIC OSCILLATORS, AND SYNTHESIZED SIGNAL GENERATORS, ELECTRONIC CIRCUIT AND SYSTEM COMPONENTS, NAMELY, KLYSTRONS, MODE ALIGNMENT MODULATORS, FREQUENCY RANGE EXTENDERS, ANALOG DISPLAY UNITS, SYNTHESIZERS, POWER SUPPLIES, ELECTRONIC FILTERS AND AMPLIFIERS, RF/MICROWAVE INTEGRATED SUBASSEMBLIES, MODULATORS, PHASE-LOCK INTERFACES, AND YIG OSCILLATORS AND FILTERS; ELECTRONIC MEASURING AND TESTING APPARATUS, NAMELY, SPECTRUM ANALYZERS, NETWORK ANALYZERS, POWER METERS, VECTOR ANALYZERS, VOLTMETERS, TRANSCEIVER ANALYZERS AND TESTERS, COMMUNICATION TEST SETS, TEST RECEIVERS, AND FIELD INTENSITY METERS; COMPUTER EQUIPMENT, NAMELY ANALOG DISPLAY UNITS, COMPUTER KEYBOARDS, PRINTERS AND FLOPPY DISCS CONTAINING PRE-RECORDED COMPUTER OPERATING SYSTEM PROGRAMS; AND ELECTRONIC ACCCESSORIES AND PARTS, NAMELY, WIRE, CABLE, TEST PLUGS, ADAPTORS, CLAMPS, PROBES, FILTERS, AMPLIFIERS, RADIO RECEIVERS, OVERLOAD PROTECTORS, HEADPHONES, NON-CONSUMER TYPE RADIO RECEIVERS, RADIO TUNING UNITS, ANTENNAS AND PARTS THEREOF