26 DETECTION AND POWER MEASURING INSTRUMENTS FOR MICROWAVE ELECTROMAGNETIC WAVE ENERGY-NAMELY, CRYSTAL MOUNTS, BOLOMETERS AND BOLOMETER MOUNTS, WATER LOAD CALORIMETERS, WATER LOAD CALIBRATORS, HIGH POWER WATER LOADS, HARMONIC GENERATORS, HARMONIC GENERATORS AND MIXERS, MICROWAVE REFRACTORS, AND TEST BENCHES; FREQUENCY MEASUREMENT INSTRUMENTS-NAMELY, FREQUENCY METERS AND FILTER CAVITIES; FIXED, VARIABLE AND CALIBRATED ATTENUATORS; TERMINATIONS; AMPLIFIERS; DUMMY LOADS; TUNERS; STANDING WAVE DETECTORS; ADJUSTABLE AND PRECISION ADJUSTABLE WAVEGUIDE SHORTS; ECHO BOXES; AND RELATED PARTS, COMPONENTS AND ACCESSORIES