TM-11-5820-222-35

• FIELD AND DEPOT MAINTENANCE MANUAL RADIO SETS AN/VRC-24 AND  AN/TRC-68
• WARNING
• DIRECT SUPPORT, GENERAL SUPPORT, AND DEPOT MAINTENANCE MANUAL is changed as follows
• APPENDIX A. REFERENCES
• Direct Support, General Support and Depot Maintenance Manual is changed as follows
• Bandwidth Selectivity Test
• Figure 118. Receiver audio output and audio level adjustment test
• Measure and record the audio output
• Figure 119. Audio frequency response characteristics and distortion measurements tests
• Broadband audio test procedure
• Figrue 119.3. Transmitter final test setup
• Side Tone Test
• Figure 119.4. Sidetone test
• RF power output
• DS, GS, and Depot Maintenance Manual is changed as follows
• Gneral Test Conditions
• Electrical Circuit Tests
• Figure 115. Receiver sensitivity and age characteristics test
• Figure 116. Receiver squelch test
• Figure 117. Bandwidth/slectivity test
• Figure 118. Receiver audio output and audio level adjustment test
• Audio Distortion Measurements
• Figure 119. Audiofrequency response characteristics and distortion measurements tests
• Figure 119.1. Receive noise rejection and signal plus noise-to-noise tests
• Transmitter Tests
• Broadband audio test procedure
• Figure 119.3. Transmitter final test setup
• Automatic Modulation Limiter Test
• Carrier Noise Level Test
• Figure 119.4. Sidetone test
• Summary of Test Data
• DS, GS and Depot Maintenance Manual is changed as follows
• Differences in Models
• Figure 111.1. Centrifugal Fan HD-390A/U, partially disassembled
• Field and Depot Maintenance Manual is changed as follows
• Internal Differences in Models-continued
• Figure 2-1. Broadband filter circuit for Radio Sets AN/VRC-24A and AN/TRC-68A
• Figure 2.2. Changes to circuit of NOR-BB switch S801 in Radio Sets AN/VRC-24A and AN/TRC-68A
• Figure 64. First IF amplifier subunit, bottom and left side view
• Figure 67. Relay subunit, top view
• Caution
• CHAPTER 6.1. FOURTH ECHELON TESTING PROCEDURES
• Figure 113.1. Special test cable fabrication
• Special Requirements
• Test Procedure-continued
• Figure 113.2. Power Supply PP-1494?U voltage and ripple tests, test setup
• Dynamotor DY-151/U Voltage and Ripple Tests
• Figure 113.4. RT-323/VRC-24 or RT-441/TRC-68 Transmit frequency stability, metering, and power output tests, test setup
• Summary of Test Data
• Summary of Test Data-continued
• RADIO SETS AN/VRC-24 AND AN/TRC-68
• CHAPTER 1. BLOCK DIAGRAM THEORY
• Simplified Transmitting Signal Path
• Figure 1. Receiving signal path, simplified block diagram.
• CHAPTER 2. RECEIVER THEORY
• Squelch Circuit
• Section II. DIRECTIONAL COUPLER AND RF INPUT STAGES
• Input Circuit
• First Receiver Mixer V104
• Figure 5. First rf amplifier V102, second rf amplifier V103, and first receiver mixer V104, schematic diagram
• Section III. UHF INJECTION SUBUNIT
• First Uhf lnjection Amplifier V203
• Figure 6. First oscillator V201 and frequency tripler V202, schematic diagram
• Figure 7. First, second, and third uhf injection amplifier V203, V204 and V205, schematic diagram
• Section IV. FIRST IF. STAGES, SECOND RECEIVER MIXER AND SECOND OSCILLATOR
• Figure 8. First and secondif amplifiers V301 and V302, and second receiver mixer V303, schematic diagram
• Second Oscillator V305
• Section V. THIRD RECEIVER MIXER AND THIRD OSCILLATOR SECTION
• 500-Kc If. Filter FL901
• Second 500-Kc If. Amplifier V502
• First Audio Amplifier V504
• Figure 11. First, second, and third 500-kc if. amplifiers V501, V502, and V503, schematic diagram
• Figure 12. Detector, avc and noise limiter circuits, and first audio amplifier V504, schematic diagram
• Section VII. SQUELCH AND AUDIO OUTPUT SECTION
• Second Receiver Audio Amplifier V804
• Audio Output Circuits
• Headset Audio.
• Figure 15. Audio output circuits, schematic diagram
• CHAPTER 3. TRANSMITTER THEORY
• Figure 16. RT unit, transmitting signal path, block diagram
• Section II. LOW-LEVEL STAGES
• First and Second If. Amplifiers V301 and V302
• First, Second, and Third Rf Amplifiers V102, V103, and V104 on Transmit
• Section III. HIGH-LEVEL RF AND MODULATOR STAGES
• Transmitter Power Amplifier V106
• Modulator Driver V804 and Transmitter Modulator V804 through V808
• Limiter Rectifier V802B
• Figure 20. Audio preamplifier V803, limiter rectifier V802B, and audio input circuits, schematic diagram.
• CHAPTER 4. THEORY OF BROADBAND, CONTROL, METERING, POWER, DISTRIBUTION, AND FREQUENCY SELECTION STAGES
• Section II. METERING CIRCUITS
• PA Ib Position
• LINE V Position
• S-METER Position
• Figure 22. Metering circuits, schematic diagram.
• Figure 23. Bias and B+ distribution, schematic diagram
• Section III. B+ AND BIAS DISTRIBUTION
• Section IV. POWER CONTROL CIRCUITS
• Radio Set AN/TRC-68 Power Control
• Figure 24. Radio Set AN/VRC-24, power control, schematic diagram.
• Section V. CONTROL AND FREQUENCY SELECTION CIRCUITS
• Figure 26. Pushto-talk circuit, schematic diagram
• Local Channel Selection
• Operation of 1-Mc Automatic Positioner
• Manual Frequency Selection
• Figure 27. Channel selector circuits, schematic diagram
• Automatic Positioner Functions
• Figure 28. Manual frequency selector circuits, schematic diagram.
• Section VI. POWER SUPPLIES AND MINOR COMPONENTS
• Radio Set Control C-1439/U
• Figure 29. Power Supply PP-1494/U, schematic diagram
• Centrifugal Fan HD-390/U
• Figure 30. Radio Set Control C-1439/U, schematic diagram
• Figure 31. Centrifugal Fan HD-390/U, schematic diagram.
• Figure 32. Dynamotor DY-151/U, schematic diagram.
• Figure 33. Receiver-Transmitter Case CY-2557/VRC-24, schematic diagram.
• Figure 34. Receiver-Transmitter Case CY-2712?TRC-68, schematic diagram
• CHAPTER 5. TROUBLESHOOTING
• Section II. SYSTEM APPLICATION TROUBLESHOOTING
• Defective Broadband Operation
• Broadband Operation Troubleshooting Chart-continued
• Figure 35. Retransmission circuits, schematic diagram.
• Section III. UNIT TROUBLESHOOTING
• 300V B+ short-circuit test
• 125V B+ short-circuit test
• Bias short-circuit tes
• Figure 37. Receiver-Transmitter RT-323/VRC-24 and RT-441/TRC-68 filament circuits, schematic diagram
• Test Setup
• Troubleshooting Chart for OA-2648/VRC-24, Power Supply and Power Circuits
• Troubleshooting Chart for Rt Unit.
• Receiver
• Receiver-continued
• Receiver-continued
• Transmitter
• Transmitter-continued
• Troubleshooting Chart Using Radio Set Control C-1439/U
• Troubleshooting Chart Using Radio Set Control C-1439/U-continued
• Figure 38. Troubleshooting test setup.
• Figure 39. Power Supply PP-1494/U, top view.
• Figure 41. Power Supply PP-1494/U, bottom view.
• Figure 43. Receiver-Transmitter Case CY-2712/TRC-68, front view, ac case blower connected.
• Figure 45. Dynamotor DY-151/U, side view
• Figure 46. Mounting MT-1436/U, rear view, terminal box, cover removed.
• Figure 47. Main frame, right side view.
• Figure 48. Main frame, rear view
• Figure 49. Receiver-transmitter unit front panel, rear view.
• Figure 50. First oscillator, crystal cover removed
• Figure 51. First oscillator, left side view.
• Figure 52. First oscillator, right side view.
• Figure 54. Uhf injection subunit, bottom view, first oscillator assembly folded out.
• Figure 56. 3.0- to 3.9 mc if. subunit, topview, crystal cover removed.
• Figure 58. 3.0 to 3.9 mc if. subunit, bottom view.
• Figure 60. 500-kc if. amplifier subunit, bottom view, outer side of detector plate.
• Figure 61. 500-kc if. amplifier subunit, bottom view, inner side of detector plate.
• Figure 62. First if. amplifier subunit, top view.
• Figure 64. First if. amplifier subunit, bottom and left side view
• Figure 65. First if. amplifier subunit, bottom view.
• Figure 67. Relay subunit, top view.
• Figure 69. Rf and power amplifier subunit, right side view.
• Figure 70. Rf and power amplifier subunit, covers removed.
• Figure 71. Rf and power amplifier subunit, tube chassis, bottom view.
• Figure 73. Rf and power amplifier subunit, tube chassis removed, power amplifier folded out.
• Figure 75. Rf and power amplifier subunit, tube chassis removed, power amplifier folded out.
• Figure 77. Audio amplifier and modulator subunit, bottom view, inner sides of terminal boards.
• Figure 79. 500-kc if. filter and low pass filter, side view.
• Figure 81. Directional coupler, rear view.
• Figure 82. Radio Set Control C-1439/U, rear view, cover removed.
• Figure 83. Location chart for subunits, subunit connectors, and subunit retaining hardware.
• Figure 84. 500-kcif. amplifier subunit tube socket voltage-resistance diagram
• Figure 85. RF and power amplifier subunit, tube socket voltage-resistance diagram
• Figure 86. Uhf injection subunit, tube socket voltage-resistance diagram
• Figure 87. 3.0- to 3.9 mc if. subunit, tube socket voltage-resistance diagram.
• Figure 88. Audio amplifier and modulator subunit, tube socket voltage-resistance diagram.
• Figure 89. First if. amplifier subunit, tube socket voltage-resistance diagram.
• Audio Stage Gain on Receive
• Sensitivity Checks
• Isolating Trouble Within a Stage
• Transformer or relay coil
• CHAPTER 6. REPAIRS AND ALIGNMENT
• Removal and Replacement of First If. Amplifier Subunit
• Removal and Replacement of Audio Amplifier and Modulator Subunit
• Removal and RepIacement of 500-Kc and Low-Pass Filter Assembly
• Removal and Replacement of Frequency Selector
• Section II. REPAIRS
• Removal and Replacement of Frequency Multiplier-Amplifier Assembly
• Removal and Replacement of Uhf Capacitor Tuning Shaft
• Removal and Replacement of Rf and Power Amplifier Subassemblies
• Figure 94. Uhf injection subunit, bottom view, cover plate removed, first oscillator folded out.
• Removal of Power Amplifier Rotor Assembly
• Figure 95. Rf and power amplifier subunit, front view
• RT-323/VRC-24(*) or RT-441/TRC-68(*) Transmit Frequency Stability, Metering, and Power Output Tests
• Figure 113.5. RT-323/VRC-24(*) or RT-441/TRC(*) modulation and modulation limiting tests, test setup
• RT-323/VRC-24(*) or RT-441/TRC-68(*) Modulation Limiting Tests
• Figure 113.6. RT-323/VRC-24 or RT-441/TRC-68 transmit frequency response, carrier noise, and distortion tests, test setup
• RT-323/VRC-24(*) or RT-441/TRC-68(*) Transmit Frequency Response, Carrier Noise, and Distortion Tests
• Figure 113.7. RT-323/VRC-24(*) or RT-441/TRC-68(*) receiver sensitivity, resettability, audio output, signal plus noise-to-noise, and squelch tests, test setup
• RT-323/VRC-24(*) or RT-441/TRC-68(*) Receiver Sensitivity, Resettability, Audio Output, Signal Plus Noise-to-Noise, and Squelch Tests
• Figure 113.8. RT-323/VRC-24(*) or RT-441/TRC-68(*) receive frequency response and distortion tests, test setup
• RT-323/VRC-24(*) or RT-441/TRC-68(*) Receive Frequency Response and Distortion Tests
• Figure 113.9. RT-323/VRC-24(*) or RT-441/TRC-68(*) selectivity and symmetry tests, test setup
• RT-323/VRC-24(*) or RT-441/TRC-68(*) Selectivity and Symmetry Tests
• Figure 113.10. Radio Set Control C1439/U tests and overall operation test, tests setup
• Figure 113.10. Radio Set Control C1439/U Tests and Overall Operation Test
• Disassembly and Reassembly of Frequency Selector (4th Echelon)
• Disassembly of Front Plate Components
• Reassembly of Front Plate Components
• Separation of Front and Rear Plates
• Disassembly of Front Plate
• Reassembly of Front Plate
• Figure 96. Frequency selector assembly, exploded view
• Disassembly of Rear Plate
• Reassembly of Rear Plate
• Reassembly of Rear Plate-continued
• Figure 97. Frequency selector front plate, exploded view
• Figure 97. Continued
• Figure 98. Frequency selector rear plate, exploded view
• Figure 98. Continued
• Adjustment and Synchronization of Frequency Selector.
• Synchronization of 10.0-mc auto-matic positioner at 220.0.
• Lubrication
• Figure 99. Frequency selector, right-side view.
• First If. Amplifier Subunit Lubrication
• Figure 100. Frequency selector, rear view.
• Figure 101. Frequency selector, front view.
• Figure 102. Frequency selector, bottom view
• Figure 103. Frequency selector, left side view.
• Figure 105. Torque meter adapter.
• Figure 108. Uhf injection subunit, lubrication points.
• Figure 110. 3.0- to 3.9-mc if. subunit, lubrication points.
• Section III. ALIGNMENT
• Preliminary Test Setup.
• Alignment of Second Oscillator
• Alignment of 3.0- to 3.9-Mc If. Subunit
• Procedure.
• Alignment of First Oscillator
• Alignment of Uhf Injection Subunit Step Tuner
• Alignment of Rf and Power Amplifier Subunit
• Procedure-continued
• Section IV. ADJUSTMENTS
• S-METER Adjustment
• Procedure.
• CHAPTER 7. FINAL TESTING
• Receiver Sensitivity Test
• Resettability Tests
• Squelch Test
• Audiofrequency Response Characteristics
• Figrue 116. Receiver audio output, frequency response and distortion test setup, block diagram
• Audio Distortion Measurements
• Transmitter Rf Power Output
• Figure 118. RF power output, test setup, block diagram
• Automatic Modulation Limiter
• Figure 119. Transmitter final test setup, block diagram
• Transmitter Audiofrequency Response
• Overall Distortion Test
• Sidetone Test
• Local Channel Selection.
• Figure 120. Color code marking for military standard resistors.
• Figure 121. Color code marking for military standard capacitors
• Figure 122. Electrical Special Purpose Cable Assembly CX-4630/U, schematic diagram
• Figure 123. Electrical Special Purpose Cable Assembly CX-4882/U, schematic diagram.
• Figure 124. Electrical Special Purpose Cable Assembly CX-4884/U, schematic diagram.
• Figure 125. Electrical Special Purpose Cable Assembly CX-4883/U, schematic diagram.
• Figure 126. Mounting MT-1436/U, schematic diagram.
• Figure 127. RT unit, main frame wiring diagram
• Figrue 128.1. Receiver-Transmitter RT-323/VRC-24 or RT-441/TRC-68, main schematic diagram (part 1 of 2)
• Figrue 128.2. Receiver-Transmitter RT-323/VRC-24 or RT-441/TRC-68, main schematic diagram (part 1 of 2)
• APPENDIX. REFERENCES
• INDEX
• INDEX-continued
• INDEX-continued
• INDEX-continued
• INDEX-continued
• INDEX-continued
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