21 CATV ELECTRONIC EQUIPMENT-NAMELY, CARRIER GENERATORS, AMPLIFIERS, POWER SUPPLIES, POWER COUPLERS, PADS, EQUALIZERS, DIRECTIONAL COUPLERS, LINE SPLITTERS, TAPS, TERMINATIONS, FILTERS, THERMAL EQUALIZING UNITS, PROBES, COAXIAL CABLE, CABLE CONNECTORS AND FITTINGS AND MARKER GENERATORS AND CROSS-MODULATION ANALYERS