REPAIR AND RESTORATION OF THE SR-400
3
WDØGOF 6/22/20014
TABLE OF CONTENTS
INTRODUCTION .................................................................................................................................................. 2
1. SR-400 INITIAL INSPECTION AND TESTING. ............................................................................................ 5
1-1. VISUAL AND MECHANICAL INSPECTION ......................................................................................... 5
1-2. RECAPPING; .............................................................................................................................................. 5
1-3. AFTER MARKET MODIFICATIONS ...................................................................................................... 5
1-4. INITIAL POWER UP ................................................................................................................................. 6
1-4-1. TEST EQUIPMENT REQUIRED ....................................................................................................... 6
1-4-2. POWER UP PRE-SET CONDITIONS................................................................................................ 6
1-4-3. INITIAL POWER UP TESTS ............................................................................................................. 6
1-5. CHECK AND ADJUSTMENT OF OSCILLATORS: ............................................................................... 7
1-5-1 TEST EQUIPMENT REQUIRED ........................................................................................................ 7
1-5-2. CARRIER OSCILLATOR:.................................................................................................................. 7
1-5-3. HETERODYNE OSCILLATOR: ........................................................................................................ 7
1-5-4. VFO: ..................................................................................................................................................... 8
1-5-4-1. RIT/CAL ....................................................................................................................................... 8
1-5-4-2. VFO CORRECTOR...................................................................................................................... 8
1-5-4-3. VFO ALIGNMENT ...................................................................................................................... 8
2. RECEIVER FAULT ISOLATION ................................................................................................................... 10
2-1. EQUIPMENT REQUIRED. ...................................................................................................................... 10
2-2. STANDARD TEST CONDITIONS ......................................................................................................... 10
2-3. PROCEDURE OVERVIEW & PRESET CONDITIONS ........................................................................ 10
2-4. RECEIVER FAULT ISOLATION CHART ............................................................................................. 11
2-5 AGC TEST ................................................................................................................................................. 12
2-5-1. AGC FIGURE OF MERIT ................................................................................................................ 12
2-5-2. AGC THRESHOLD ADJUSTMENT ............................................................................................... 12
2-6. S-METER ZERO ....................................................................................................................................... 12
2-7. CAL OSCILLATOR ................................................................................................................................. 12
2-7-1. CYCLONE II TEST ........................................................................................................................... 12
2-7-2. CYCLONE III TEST ......................................................................................................................... 12
3. TRANSMITTER TESTING ............................................................................................................................. 13
3-1. TEST EQUIPMENT REQUIRED ............................................................................................................ 13
3-2. STANDARD TEST CONDITIONS ......................................................................................................... 13
3-3. BIAS ADJUST .......................................................................................................................................... 14
3-4 INITIAL TRANSMITTER TESTS ............................................................................................................ 14
3-4-1 TRANSMITTER POWER TEST ....................................................................................................... 14
3-5, TRANSMITTER FAULT ISOLATION ................................................................................................... 15
3-5-1, DRIVER CAPACITIVE PICKUP TOOL ......................................................................................... 15
3-5-2, LOW OR NO POWER ACROSS ALL BANDS .............................................................................. 16
3-5-3, NO OR LOW POWER ON A SINGLE BAND. ............................................................................... 16
4. SUBSYSTEM TROUBLESHOOTING AND TESTING ................................................................................ 17
4-1 VFO DRIFT ................................................................................................................................................ 17
4-2. V15 RX FAULT ISOLATION.................................................................................................................. 17
4-3. V9B RX FAULT ISOLATION ................................................................................................................. 17
4-4. V9A RX FAULT ISOLATION ................................................................................................................. 17
4-5. V7A RX FAULT ISOLATION ................................................................................................................. 17
4-6. XTAL RX FILTER/NOTCH FAULT ISOLATION ................................................................................ 17
