AAC CADET INSTRUCTOR S HANDBOOK RADIO SET AN/PRC-77

Transcription

1 AAC CADET INSTRUCTOR S HANDBOOK RADIO SET AN/PRC

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4 i PREFACE Aim 1. The aim of this publication is to provide Cadets with the information required to conduct lessons on the Radio Set AN/PRC-77. It provides information for Tier 1 training through to the Cadet Radio Operator specialist course. The publication has been produced by the Training Cell, HQ NT AAC BN. Level 2. This publication is not the source document however it is to be used as the reference for AAC communications training. Scope 3. This publication is a guide and was correct at the time of publication. The source for this is the Technical Manual, User Handbook, Radio Set AN/PRC-77. It also contains descriptions of equipment associated with the AN/PRC-77. AMENDMENTS 1. The following promulgated amendments have been made to this publication. Amendment List Amended By Number Date (Print Name and Initials) 1 Nov 05 Rewrite. Radio interoperability added to Chapter 3 2 May 07 Updated with battery information and reissued Nov 07 Reprinted Date of Amending

5 ii CONTENTS Preface, Amendment Page Contents i ii Paragraph CHAPTER ONE - Radio Set AN/PRC-77 Introduction 1.01 Description and data 1.02 Technical characteristics 1.03 Components 1.04 General description 1.05 Additional equipment required 1.06 CHAPTER TWO - Installation Components 2.01 Siting 2.02 Installation of battery, dry 2.04 Assembly and installation for manpack operation 2.05 Installation of antennas 2.06 CHAPTER THREE - Operating instructions Cautions 3.01 Receiver-Transmitter, Radio RT-841/PRC-77, 3.03 Controls, Indicators, and Connectors 3.04 Preset channel frequencies 3.05 Operating procedure 3.06 Interoperability 3.07 Closing down procedure 3.10 Recognition and identification of jamming 3.11 Anti jamming 3.12 CHAPTER FOUR - Operator Maintenance Instructions Scope of maintenance 4.01 Preventative maintenance 4.02 Preventive Maintenance Service and Inspection Periods 4.03 Operators Daily Preventive Maintenance Checks 4.05 Operators Weekly Preventive Maintenance Checks 4.06 Cleaning 4.07 Visual inspection 4.08 Operational checklist 4.09 Antenna AT-984A/G CHAPTER FIVE Ancillary Equipment Description 5.01 Siting 5.03 Installation 5.04 Radiation pattern 5.05 Maintenance 5.06

6 iii Retransmission Cable Kit MK-456/GRC Description 5.07 Selection of frequencies 5.09 System set up 5.10 Radio Set Control Group AN/GRA 39 B Description 5.11 Operation 5.13

7 CHAPTER ONE Radio Set AN/PRC-77 Introduction 1.01 This manual describes the Radio Set AN/PRC 77 and covers its installation, operation and operator s and organisational maintenance. It includes instructions for cleaning, checking, and inspecting the equipment, as well as replacing the battery. The basic issue items list, maintenance allocation chart, and the organisational repair parts and special tool lists are also included in this manual. Description and Data 1.02 The purpose and use of the radio set is described as follows: a. Radio Set AN/PRC 77 (radio set) is a short-range, man pack portable, frequency modulated (fm) receiver-transmitter used to provide two-way voice communication. b. Receiver Transmitter, Radio RT-841/PRC-77 is also used as part of Radio Sets AN/GRC-160 and AN/VRC-64. c. The AN/PRC-77 has a frequency range identical with, and can communicate with, many fm radio sets. d. When used at a fixed location, the radio can be remotely controlled by Radio Set Control Group AN/GRA-39. The operating range of the AN/PRC 77 can be extended by use of a fixed, elevated, ground plane antenna or a long-wire antenna, Antenna AT-984/G. Technical Characteristics 1.03 The technical characteristics for the Radio Set AN/PRC 77 are as follows: a. Frequency range: (1) low band to KHz; and (2) high band to KHz b. Number of channels: 920 c. Distance range: 8 km. Varies with siting d. Types of antennas: (1) short antenna (antenna AT-892/PRC-25; 3 feet long, semi grid steel tape); and (2) long antenna (antenna AT-271A/PRC; 10 feet long, multi section whip). e. Battery life: 24 hours (with a 9:1 receive-transmit ratio).

8 Components 1.04 The components of the radio set are listed in the basic items issue list and are illustrated in figure 1. General Description Figure 1 Radio Set AN/PRC-77 Components 1.05 The radio set consists of receiver-transmitter, PRC-77 and minor components. The description of the radio and of the minor components is below. a. Receiver-Transmitter/ RT-841/PRC-77 consists of the receivertransmitter, the receiver-transmitter case, and the Battery Box and these are described as follows: (1) The receiver-transmitter is held in the receiver-transmitter case by four captive screws. The Battery Box is attached to the receivertransmitter case by two clamps. The complete radio, when assembled, is watertight. All controls are located on the front panel. A battery plug projects from the receiver-transmitter and mates with the connector of the Battery Box; (2) The Battery Box is a lightweight metal case that protects and houses the Battery Dry. The Battery Dry sits on a foam rubber pad that is attached to the bottom of the Battery Box.

9 b. Minor components of the radio are as follows: (1) Antenna PRC-25. The PRC-25 is a one section, three foot long whip antenna. A spring at its base allows for positioning of the antenna to keep it in a vertical position, regardless of the position of the PRC-77. This antenna is used for general short range service and, because of its steel tape construction, can be folded into a small space, (2) Antenna AT-271A/PRC. The AT-271A/PRC is composed of six sections; each section fits into the end of a wider section. A braided plastic cord, under spring tension, is threaded through the sections to keep them together in the operating condition. When the sections are folded, the cable keeps them together as a group, to prevent the loss of individual sections. Spring tension is provided by a spiral spring in the base section. This antenna is used when maximum range is required, (3) Support, Antenna AB-591/PRC-25. The AB-591/PRC-25, which is of rigid tubular construction, and is used as a main support of the 9 rod antenna, AT- 271A/PRC, (4) Harness, Electrical Equipment. The carry bag is made of cotton duck. It is used to secure the radio so that it can be carried on the operator s back, (5) Bag, Cotton Duck. The bag is sectionalised into several pockets that are used to store the two antennas, the antenna support and the Handset, and (6) Handset. The Handset consists of a microphone and receiver section for transmitting and receiving signals. The connecting cord is retractable and terminates in a five-pin connector. A push-to-talk switch is mounted in the handle. Additional Equipment Required 1.06 The following additional equipment is required for the radio: a. Battery, Dry is not supplied as part of the radio but is required for its use. The battery is supported and housed in the Battery Box. The battery consists of 10 D Cell energisers giving a total voltage of 15 volts DC. The batteries are provided with a female connector to mate with the radio. Extreme care should be used when installing as the socket is easily damaged if not aligned properly. When refitting the battery case, the gas release plug must go to the opposite end to the plug and socket. The new battery NSN is

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11 CHAPTER TWO Installation Components 2.01 The following table is a list of the components for the AN/PRC-77 set: a. Receiver transmitter, radio RT-841/PRC-77, b. Battery Box CY-2562/PRC-25, c. Support, Antenna AB-591/PRC-25, c. Antenna AT-892/PRC-25 (folded), d. Antenna AT-271A/PRC (folded), e. Harness, Electrical Equipment ST-138/PRC-25, f. Bag, Cotton Duck CW-503/ PRC-25, and g. Handset H-189GR. Siting 2.02 The radio operates at low power and on high frequencies, therefore, the location of the equipment greatly affects it operating range. Normally, a line-of-sight range can be expected, that is, if the other station can be seen then satisfactory operation is probable. An intervening hill or a tall building may hamper or prevent contact with other stations Valleys, densely wooded areas, and low places are poor sites. Location on a hilltop or a tower will increase the operating distance. If possible, avoid locations near a source of electrical interference, such as power or telephone lines, radar sets, and field hospitals. Installation of Battery 2.04 The following data is used for the installation of the battery: a. Stand the radio upside down on a level surface. Ensure there is no handset or antenna connected; b. Release the two clamps by lifting the topmost part of each clamp up and away from the receiver-transmitter case; c. Lift the Battery Box off; d. Place the battery onto the radio taking extreme care to locate the pins into the socket. If this is not done, the pins will destroy the plastic socket; e. Slide the battery box over the battery until it meets the receiver-transmitter case. The gas release plug in the box MUST go to the opposite end to the power plug/socket; and f. Refasten the two clamps by pushing them simultaneously. Caution: Remove the battery when the equipment is not in use for more than one day.

12 Assembly and Installation for Man Pack Operation 2.05 The assembly and installation procedures for the man pack operation is as follows: a. Attach the harness, electrical equipment to the radio as instructed in the following areas below: (1) place the harness, electrical equipment flat on a level surface with the metal braces facing up; (2) place the radio on the harness, electrical equipment with its front panel toward the top and the battery box resting on the metal braces of the harness, electrical equipment; (3) fasten the radio to the harness, electrical equipment with the two retaining straps; feed the metal-tipped strap from below, through the centre slot on the buckle, and then down through the end slot in the buckle; and (4) clip the bag cotton duck to the harness, electrical equipment. b. Mount the harness, electrical equipment on the operator as follows: (1) install the desired antenna; (2) connect the handset to one of the AUDIO connectors on the front panel of the radio; (3) place the harness, electrical equipment with the radio attached, on the operator s back. Place the shoulder straps over the operator s shoulders; (4) feed the end of the right lower strap through the right shoulder strap ring. Feed the metal tip of the strap from below, through the centre slot in the buckle, and then down through the end slot in the buckle; (5) feed the end of the left lower strap through the left shoulder strap ring. Feed the metal tip of the strap from below, through the centre slot in the buckle, and then down through the end slot in the buckle; and (6) hook the two belts to the combat belt. Installation of Antennas 2.06 Use the whip (short antenna) when maximum range is not required. Use the (long antenna) when maximum range is required. The installation procedures are as follows: a. Antenna Whip; (1) Remove the cover from the antenna mount; (2) Screw the gooseneck into the radio antenna mount; (3) Screw the bottom of the whip antenna into the gooseneck.

13 b. Antenna Long; (1) remove the cover from the antenna mount; (2) screw, Long Antenna, into the antenna mount; (3) extend the long antenna by holding the base section (the heaviest section) and carefully whipping it outward. If all the sections are not secure, repeat this procedure or insert the sections individually by hand; and (4) secure the Long Antenna and into the Support, Antenna. Caution. If as little as 1mm gap is allowed between the top of the whip antenna mount and the flat bottom of the antenna, the antenna may break at this point leaving the threaded portion in the antenna mount. A plastic filling has been included among the threads but it may become worn and ineffective in preventing the antenna from being unscrewed by vibration. To safe-guard the antenna, periodically tighten it into the antenna mount. Figure 2. Assembly for manpack operation

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15 CHAPTER THREE Operating Instructions Cautions 3.01 Do not change the MHz (Mc) or KHz (Kc) tuning controls or the band switch while the radio is keyed for transmission (handset push to talk switch depressed). Damage to modules in the radio may result or the wrong channel frequency may be set up, thus preventing radio communications Battery power should be between 12.5 and 15 volts dc, with (+) applied to the B terminal on the battery connector (at the back of the receiver-transmitter) and minus (-) applied to the A terminal. Dc not interchange these batteries polarities; to do so results in damage to modules in the radio. Receiver-Transmitter, Radio RT-841/PRC-77, Controls, Indicators, and Connectors 3.03 The following table describes the control, position, function and actions of the PRC-77 radio: Figure 3. Controls, Indicators and Connectors Control/Indicator/Connector Function Switch Function OFF Turns off power ON Applies power SQUELCH RETRANS LITE Applies power and reduces rushing noise when no signal is received Permits radio relay operation Switches a light inside the frequency display window for night setting. Band Switch Mc tuning control KHz tuning control Selects lower frequency band, A band Selects higher frequency band. B band Tunes radio in 1MHz steps as indicated by the channel dial Tunes radio in 50 KHz steps as indicated by channel dial

16 REC-TRANS FREQUENCY dial PRESET levers VOLUME control AUDIO connectors ANT mount ANT connector POWER connector Indicates operating frequency in MHz and KHz Note: MHz and KHz is the current terminology. Permit rapid location of two pre-set frequencies Varies receiver volume Provides connections for handsets or retransmission cable Provides connection for antenna AT-271A/PRC or AT- 892/PRC-25 Provides connections for antenna (Lightweight, RC-292 or vehicular antenna Provides connections for external power supply when RT- 841/PRC-77 is used as part of vehicular radio set configurations. The radio will not operate if the cover for the power connector is not in place. Pre-setting Channel Frequencies 3.04 On the MHz and KHz controls are pre-set levers that can be set to catch the stops on each control. Thus, when two channels are pre-set, they can be selected without looking at the channel dial. Use the procedures in the following below to set the Mc control. Note: when pre-setting the controls, the two frequencies to be set must be considered the lower and the higher frequencies; and the sections of each tuning control as the inner (next to the front panel) and the outer sections. a. Pre-setting the KHz tuning control. The KHz control is set before the MHz control. Determine the lower and higher KHz frequencies. (for example 35 in MHz, 70 in MHz, etc): (1) set the pre-set lever away from the KHz control; (2) set the KHz control so that the lower frequency appears in the channel; (3) position the pre-set lever forward against the control and loosen the wingnut on the control; (4) pull up on the lower section of the control and turn it counter clockwise until the stop on the lower section strikes the pre-set lever. Tighten the wingnut; (5) position the pre-set lever away from the control; (6) turn the control until the higher frequency appears in the channel dial (both sections move); (7) loosen the wingnut and position the pre-set lever forward against the control;

17 (8) without disturbing the setting of the lower section, pull on the upper section and turn it clockwise until its stop strikes the pre-set lever; (9) keeping the upper section against the pre-set lever, tighten the wingnut; (10) check the settings for the lower and higher KHz frequency settings by turning the control counter clockwise to the stop for the lower KHz frequency, and clockwise to the stop for the higher frequency; and (11) set the KHz control. b. Pre-setting the MHz tuning control. The MHz control is set after the KHz control. Determine the assigned lower and higher mc frequencies. (for example: 59 in MHz, 39 in MHz, etc): (1) pre-setting MHz frequencies in same band. The procedure for presetting the lower and upper sections of the mc control for mc frequencies that are in the same band are the same as those given for the KHz control in the above picture. That is, the lower mc frequency in the band is set with the lower section of the control; and the higher mc frequency in the same band is set with the upper section; (2) pre-setting MHz frequencies in different bands. Note that there are 23 positions of the control in each band: from 30 through 52 in band A; from 53 through 75 in band B; (3) when pre-setting the MHz control for frequencies that are in different bands, always set the lower section to that MHz frequency that is lower in its band than the MHz frequency in the other band. For example: 54 is lower (second position) in band A; thus, 54 MHz would be set on the lower section and 33 MHz would be set on the upper section; and (4) to pre-set the MHz control sections, use the same procedures as above with the band switch in the proper position and with the information given in the above picture. Selecting Pre-set Channels 3.05 To select a pre-set channel, proceed as follows: a. set the PRESET levers forward (toward the MHz and KHz tuning controls); b. set the BAND switch at or 53-75, depending on the channel used; c. turn the MHz and KHz tuning controls until the stops strike against the stop in the opposite direction; d. check the channel number that appears in the channel dial; e. if the incorrect channel appears in the channel dial, turn the tuning controls against the stop in the opposite direction;

18 f. if the incorrect channel still appears, perform the pre-setting procedures as given in paragraph 4; and g. to select the other pre-set channel, turn the MHz and KHz tuning controls against the other stops. If the pre-set frequency is in the other band, set the BAND switch at the other position. Operating Procedure 3.06 The operating procedure is as follows: a. set the function switch to ON. A rushing noise should be heard in the handset; b. set the BAND switch at or 53-75, depending on the frequency required; Note: if a pre-set channel is to be used, select the pre-set channel as given in paragraph 17 in place of the procedure in c below. If a pre-set channel is not to be used, make sure that the PRESET levers are back (away from the MHz and KHz tuning channels); c. turn the MHz and KHz tuning controls so that the desired frequency shows in the channel dial; d. set the VOLUME control at 4; readjust for a desired sound level in the handset; and e. Transmit as follows: (1) press the push-to talk switch on the handset; and (2) speak into the handset. f. to receive, release the push-to talk switch on the handset; g. the receiver rushing noise can be eliminated by setting the function to SQUELCH during periods when the other station is not transmitting. To determine whether squelch operation is possible, use the following procedures: (1) arrange for the distant station to send a short transmission while operating without its squelch; (2) set the function switch to ON; the rushing noise should be heard until the other station transmits; (3) arrange with the other station to turn its squelch switch to the ON position and to send a short transmission; (4) on the receiver-transmitter, set the function switch to SQUELCH; the rushing noise should stop and the distant station should be heard when it transmits; (5) if the other station cannot be heard now, reset the function switch to ON and advise the other station of the situation; and

19 Note: the failure of either station to receive transmissions from the other may indicate that the distance between the two stations is too great or that the squelch circuit of either radio station is defective. (6) if either station is moving about, leave the function switches in the ON position at both stations until it has been determined (by using the procedures in (1) through (5) above) that reception can be accomplished with the function switch at Squelch. Interoperatibility 3.07 The AN/PRC-77 can communicate with the RT-F200/500 series of radios however, a change needs to be made to the RT-F200. The AN/PRC-77 set uses wide-band FM transmissions while the RT-F200 set uses narrow-band transmission. For both radios to communicate with each other, the RT-F200 must be changed to wide-band. To do this, enter the following key sequence on the RT-F200 radio: E ENT To convert the RT-F200 back to narrow-band simply turn it OFF, then ON again or enter the following key sequence: E ENT For the AN/PRC-77 to communicate with the PINTAIL (RT-F700) hand held radio, the PINTAIL must be programmed with a sub-tone of 150 Hz on both transmit and receive otherwise the PINTAIL will not hear the AN/PRC-77 unless the squelch is open. This programming should be done to communicate with any military radio. Closing Down Procedure 3.10 The closing down procedure is as follows: a. to turn off the receiver-transmitter, set the function switch to OFF; and b. if the Long Antenna was used, disassemble it as follows: (1) unscrew the Long Antenna from the Support Antenna; (2) beginning with the top section, pull out each section from the next section and fold it along the side of the next lower section; (3) unscrew the Support, Antenna from the antenna mount; (4) store the handset, both antennas, and the Support Antenna in the Bag Cotton Duck; (5) close the flap on the Bag Cotton Duck; and (6) zeroise the radio (Set on the lowest frequency, ie MHz).

20 Recognition and identification of Jamming 3.11 Under real or simulated tactical conditions, the receiver may be jammed by unfriendly stations. Jamming is easily done by transmission of a strong signal on the frequency being used, which makes it difficult or impossible to hear the desired signal. Unusual noises or strong interference heard on the receiver may be enemy jamming, signals from a friendly station, noise from a local source or a defective receiver. To determine whether the interference is originating in the receiver, disconnect the antenna. If the interference continues, the receiver is defective. Anti-Jamming 3.12 When jamming of a channel is first noticed, notify your superior officer immediately and continue to operate the equipment. To provide maximum intelligibility of jammed signals, try the suggestions given in a through to c below. a. The effects of the enemy jamming may be reduced by placing the equipment so that nearby obstructions act as a screen in the direction of probable sites of enemy jamming transmitters. This screen action may also reduce the transmitted signal strength toward the enemy and thereby male it more difficult for him to intercept your signals. If possible try several different locations within the designated area and stay at the one where jamming is minimum; b. Vary the VOLUME control. The level of the desired signal may be raised enough to be distinguished from the jamming signal; and c. If the procedures in a and b above do not provide sufficient signal separation for operation, request change to an alternate frequency and call sign.

21 CHAPTER FOUR Operators Maintenance Instructions Scope of Maintenance 4.01 The maintenance duties assigned to the operator of the radio are listed below. The duties assigned do not require tools or test equipment: a. preventive maintenance; b. visual inspection; c. operational check; d. replacement of the Battery Dry; and e. cleaning. Preventive Maintenance 4.02 Preventive maintenance is the systematic care, servicing, and inspection of equipment to prevent the occurrence of trouble, to reduce downtime, and to ensure that the equipment is serviceable: a. systematic care. Cleaning should occur once a day. If the equipment is not used daily, the cleaning operations must be performed before operation of the equipment, after any shutdown, or once a week while the equipment is kept in standby condition. The other items must be checked before the equipment is placed in operation after it is turned off, as specified in the applicable paragraph; and b. preventive maintenance checks and services. The preventive maintenance checks and services charts outline functions to be performed at specific intervals. These checks and services are to maintain Army electronic equipment in a combat serviceable condition, that is, in good general (physical) condition and in good operating condition. To assist operators in maintaining combat serviceability, the charts indicate what to check, how to check, and what the normal conditions are; the reference column lists the illustrations, paragraphs, or manuals that contain detailed repair or replacement procedures. If the defect cannot be remedied by the operator, higher category maintenance or repair is required. Preventive Maintenance Service and Inspection Periods 4.03 Maintenance service and inspection of the radio set are required on a daily and weekly basis. In addition to the routine services and inspection, the equipment should be reinspected and serviced immediately before going on an activity and as soon as possible after completion of the activity The paragraphs below specify preventive maintenance service checks and services that must be performed once each week. If the equipment is being maintained in a standby condition, the daily and the weekly services and inspections should be accomplished concurrently.

22 Operators Daily Preventive Maintenance Checks 4.05 Daily maintenance checks should be carried out as follows: a. Completeness - Check to see that the equipment is complete b. Exterior surfaces - Remove dust, dirt, and moisture from channel window and equipment surfaces c. Controls i. check all controls for looseness and other damage ii. during operational check, check to see that the mechanical action of each control is smooth, and free from external and internal binding. d. Battery - Inspect for leakage, corrosion, and swelling. Remove the battery when radio set is not to be used for one or more days. e. Transmitter-receiver tuning - Perform the steps in the operational checklist Operators Weekly Preventive Maintenance Checks 4.06 Weekly maintenance checks should be carried out as follows: a. Handset H-189/GR - Inspect the cord for fraying, cuts, kinks, and broken insulation. b. Canvas items - for mildew and tears. c. Antenna - Inspect for damage, loose fit, and corrosion. d. Gasket - Inspect the gasket on battery box, CY- 2562/PRC for damage. Cleaning 4.07 Inspect the exterior of the radio set. The exterior surfaces should be free of dirt, grease, and fungus: a. Remove dust and other loose dirt with a clean soft cloth. b. Remove grease, fungus, and ground-in dirt from the case; use a cloth dampened (not wet) with Cleaning Compound. Warning: Prolonged breathing of cleaning compound is dangerous; make certain that adequate ventilation is provided. Cleaning compound is flammable; do not use near a flame. Avoid contact with the skin; wash off any that spills on your hands. c. Remove dust and other dirt from plugs and receptacles. d. Clean the panel and control knobs; use soft, clean cloth or brush. If dirt is difficult to remove, dampen the cloth with mild soap and water.

23 Visual Inspection 4.08 A visual inspection of the radio is as follows: a. When the equipment fails to operate properly, turn the function switch to OFF and check the following items: (1) switches and controls for incorrect setting; (2) handset H-189/GR or antenna for loose connection; and (3) battery, dry for being too weak to operate the radio. b. If the above checks do not locate the trouble, proceed to the operational checklist. Operational Checklist 4.09 The operational checklist will help the operator locate the trouble quickly. Use the corrective measures to repair the equipment. If the measures suggested do not restore normal operation, troubleshooting is required at a higher maintenance level. The following is a checklist of common faults: General Rod Antenna Whip Antenna a. Check that the knobs or screws aren t loose. It is difficult to operate without them. a. This antenna will greatly increase your chances of establishing communications. b. Ensure that the rubber mount is screwed in firmly. If not, it will snap off. c. Always operate with the antenna in the vertical position. d. If the string holding the antenna together should break, the antenna is still usable. Just assemble it by hand and do not lose any of the sections it can be repaired using hootchie cord. e. Always start folding the antenna from the tip end, never the threaded end. a. The battle whip must be used together with the flexible gooseneck even though the antenna does fit the radio without it. b. Always use the whip in the vertical position. c. If the antenna develops a kink, do first aid and splint it with a small stick and tape.

24 The Handset Operation The Battery a. The plug and socket contacts MUST be clean. Use the green scouring pad from a ration pack. The contacts should be shiny. b. Sometimes strange squealing noises can be heard in the earpiece when transmitting. This can usually be traced to dirty contacts. c. The handset is often difficult to fit on the socket. Moisten the small o-ring (inside the handset plug) and it will go on easily. Never remove this o-ring. It keeps the plug firm and stops dirt and moisture entering. Try rubber grease. a. When the radio is first switched on, allow it to sit for at least 30 seconds to allow the battery to develop its full operating voltage. b. Always have an antenna connected. c. Do not operate the set on full volume as it can cause feedback and more squealing noises. d. There are several ways to check if the set is working properly: (1) With normal volume there should be plenty of noise in the handset. (2) There should be a low growl heard when the PTT is pressed. This is the sub-tone. (3) When transmitting, you can hear yourself in the earpiece. This is called sidetone and indicates that the radio is transmitting. (4) You can hear the receive/transmit relay inside the radio clicking as you press and release the PTT. a. The battery can last up to a week or more depending upon usage. It is not necessary to replace them every day. b. When re-using batteries, it is possible to provide enough power for the radio to receive but not transmit. You should hear yourself in the earpiece when you speak. If not, the battery has insufficient power left. It may also give a buzzing sound when the PTT is pressed. Replace the battery.\ c. Always make sure that the battery is located correctly on the pins when fitting. If you close the battery box without the battery being aligned, it will damage the battery socket and it may be unusable.

25 CHAPTER FIVE ANCILLERY EQUIPMENT Antenna AT-984A/G Description 5.01 The Antenna AT-984A/G is a long wire, multiple wavelength antenna that is used to extend the normal transmission and reception range of the radio set. Figure 4. Antenna AT-984A/G, Components 5.02 The antenna consists of a canvas bag and 150 ft of wire would on a reel. The antenna is connected to the reel with a nylon cord. A cord at the other end of the wire is used to suspend the antenna wire during operation of the radio set. The end of the antenna wire is soldered to a terminal lug that is crimped around the wire and insulating tubing to strengthen the connection. The canvas bag has two locking devices on the rear for attachment to the belt of the user while unwinding the antenna wire. Siting 5.03 The operating range of the AN/PRC-77 is primarily line of sight. Avoid hills, valleys, densely wooded areas and low places. Avoid siting the radio near power sources or telephone lines. Make sure there are no obstacles preventing the antenna wire from being extended to its full length in a straight line towards the other station. Transmission and reception with a long wire is off the end of the antenna in the direction away from the radio set. Installation 5.04 Install the antenna as follows: a. Connect the terminal lug to the radio using the rubber antenna mount to clamp it to the antenna terminal. b. Tie the cord that is attached to the antenna wire to a nearby support that is capable of supporting the antenna wire when it is stretched to the other support 150 ft away. c. Unreel the antenna wire by moving in the direction of the other station. d. Stretch the antenna wire approx 1 metre above the ground by securing the reel to a building, tree, post or similar support. Use the cord that ties the antenna wire to the reel.

26 Figure 5. Connection of Wire Antenna to Radio Warning: Use warning signs or similar safety measures to prevent personnel and vehicles from running into the stretched wire. Radiation Pattern 5.05 The radiation pattern for the antenna is shown below. Figure 6. Long wire radiation pattern Maintenance 5.06 There is little maintenance with this antenna. If the terminal lug is broken, damaged or lost, cut the wire and strip off the insulation. Fit a new terminal lug by soldering and crimping.

27 Retransmission Cable Kit MK-456/GRC Description 5.07 With the retransmission cable, two AN/PRC-77 radios may be used as a radio relay for other radios sets that are too far distant to communicate directly with each other. Figure 7. Retransmission Cable Kit MK-456/GRC 5.08 It consists of a Bag, Cotton, Duck and the 50 ft cable assembly. The network box has an audio connector to which a handset or audio accessory is attached to monitor the signals being retransmitted in both directions. See figure 7. Selection of frequencies When frequencies are to be used for retransmission, they must be at least 3 MHz apart and must be selected so that the transmitter of neither radio will interfere with the receiver of the other. Frequencies should be checked beforehand for compatibility. Charts are available to assist in choosing frequencies. System setup 5.10 To establish a relay site: a. Establish communications from the relay site, with both groups. This will be on different frequencies, ie the two to be used for retransmission b. Connect the retransmission cable to both radios and set the radio to RETRANS. c. Advise both stations that the retransmission site is operating, d. Connect a handset to the audio connector of the network box to enable monitoring.

28 Note: Radios operating through a retransmission facility should pause for a second after pressing the push-to-talk switch before speaking. This enables the retrans radios to operate. Operators should remain at the site until all radio operations are normal. Radio Set Control Group AN/GRA 39 B Description 5.11 The AN/GRA-39 may be used to provide remote control of radio transmission using the AN/PRC-77 for up to 3.3 km. It consists of two parts; a Local Control situated in the CP or HQ and the Remote Control which is connected directly to the radio set. They are connected by field wire WD-1/TT. It also provides a telephone facility for an operator during the set up phase They require 6 D Cell batteries in each unit. Operation 5.13 A full description of the set up and operation of the AN/GRA-39 is contained in a separate Cadet Instructor s Handbook. A brief description is given below: a. Insert batteries into both units, b. Position the Local Control in the CP/HQ, c. Connect the field wire to the terminals and lay the wire to the desired location of the radio set. d. Connect the field wire to the terminal posts of the Remote Control. Fit a handset to the AUDIO connector and by pressing the ringer plunger and holding the function switch to TEL, communications between operators is possible. e. Connect the radio set AN/PRC-77 using the cable provided. f. Switch ON the radio and place in the SQUELCH position. g. Have the Remote Control test the radio for normal operation.