ELECTRONICS PRINTS Electronics prints are similar to electrical prints, but they are usually more difficult to read because they represent more complex circuitry and systems. This part of the chapter discusses common types of shipboard and aircraft electronic prints and basic logic diagrams. SHIPBOARD  ELECTRONICS PRINTS Shipboard electronics prints include isometric wiring diagrams that show the general location of electronic  units  and  the  interconnecting  cable  runs, elementary  wiring  diagrams  that  show  how  each individual   cable   is   connected,   block   diagrams, schematic  diagrams,  and  interconnection  diagrams. Cables that supply power to electronic equipment are tagged as explained in the electrical prints part of this  chapter.  However,  cables  between  units  of electronic  equipment  are  tagged  with  electronic designations. Figure 6-9 shows a partial listing of these designations. The complete designation list (contained in NAVSHIPS 0967-000-0140), breaks down all system designation as shown for radar in figure 6-9. Cables between electronic units are tagged to show the system with which the cable is associated and the individual cable number. For example, in the cable marking R-ES4, the R identifies an electronic cable, ES identifies the cable as a surface search radar cable, and 4 identifies the cable number. If a circuit has two or more cables with identical designations, a circuit differentiating number is placed before the R, such as 1R-ES4, 2R-ES4, and so on. Block Diagrams Block  diagrams  describe  the  functional  operation of an electronics system in the same way they do in electrical systems. In addition, some electronics block diagrams  provide  information  useful  in  trouble- shooting, which will be discussed later. A simplified block diagram is usually shown first, followed by a more detailed block diagram. Fig- ure  6-10  shows  a  simplified  block  diagram  of  a shipboard tactical air navigation (TACAN) system. The   TACAN   system   is   an   electronic   air navigation system that provides a properly equipped Circuit or system designation R-A R-B R-C R-D R-E R-EA R-EC R-ED R-EE R-EF R-EG R-EI R-EM R-ER R-ES R-ET R-EW R-EZ R-F R-G R-H R-I R-K R-L R-M R-N R-P R-R R-S R-T Circuit or system title Meteorological Beacons Countermeasures Data Radar Air search radar Carrier  controlled  approach radar Radar   identification Air search with height determining   capability Height determining radar Guided missile tracking radar Instrumentation radar Mortar locator radar Radar remote indicators Surface search radar Radar  trainer Aircraft early warning radar Three-coordinate radar Weapon  control  radar Electronic  guidance  remote control or remote telemetering CW passive tracking IFF equipment Precision timing Automatic vectoring Missile support Infrared equipment Special  purpose Radio   communication Sonar Television Figure 6-9.—Electronics circuit or system designations. aircraft with bearing and distance from a shipboard or ground radio beacon selected by the pilot. The system is  made  up  of  a  radio  beacon  (consisting  of  the receiver-transmitter group, the antenna group, and the power  supply  assembly)  and  the  radio  set  in  the aircraft. 6-11