The Crystal Test Set is intended to be used for testing, tuning, and setting the crystal currents of radar receiving equipment. For any particular equipment it is to be used as described in the handbook or applicable publication for that equipment. In most cases, however, these descriptions specify the use of a single 0-1 milliammeter so that only one current measurement can be made at a time. Furthermore, the adjustment of one of the crystal current may cause a change in the reading of one of the other crystal currents. This cannot be easily observed by the single meter method. The Crystal Test Set provides three 0-1 milliammeters so that three currents and their relationship to each other may be observed at all times. An example of a procedure for setting the crystal currents of a radar receiver is given in section 6 of NAVORD OD 7714.