1. REPAIR OF SINCLAIR TECHNOLOGIES INC. DUPLEXER MODEL MR356B
REPAIR OF SINCLAIR TECHNOLOGIES INC. DUPLEXER MODEL MR356B*2 S/N- CCV9693 FREQ MHZ MHZ BROWN BAY REPEATER JAN. 22/08

2. SCHEMATIC

3. RESOLDERED ALL CONNECTIONS
INSIDE VIEW
HAIRLINE CRACKS
RESOLDERED ALL CONNECTIONS

4. ANTENNA I/P LINE CRACKED

5. ANTENNA I/P HAIRLINE CRACK (x 10 MAGNIFICATION)

6. 2ND FILTER HAIR LINE CRACK

7. TOP VIEW
WEAK MECHANICAL SUPPORT
NO STANDOFF SUPPORT
DAMAGED SLUG

8. ACTIONS TAKEN
ALL CONNECTIONS TO CENTRE CONDUCTORS OF SEMI-RIGID LINES THAT WHERE VISIBLE WERE RE- SOLDERED.
INSPECTED ALL CONNECTIONS AFTER CLEANING WITH IPA SOLVENT AND BRISTLE BRUSH.
ANTENNA I/P CONNECTOR RE-SOLDERED AT JUNCTION OF CONNECTOR SHELL AND SEMI-RIGID LINE USING 'HOT PLATE' PROCESS.
NEW SPLIT AND STAR WASHERS ADDED TO FRONT COVER PLATE ONLY.
ALL REMAINING HARDWARE ON BACK PANEL TIGHTENED PRIOR TO TESTING.
VSWR TEST CONDUCTED ON HIGH PASS ( MHZ) AND LOW PASS ( MHZ) WITH 50 OHM LOAD ON ANTENNA PORT.

9. TEST RESULTS AFTER REPAIRS
VSWR TESTS AT MHZ WITH 50 OHM LOAD ON ANTENNA AND XMTR ON LOW PASS I/P: <1.2:1.
VSWR TESTS AT MHZ WITH 50 OHM LOAD ON ANTENNA AND XMTR ON HIGH PASS I/P <1.7:1.

10. CONCLUSION: PROBABLE CAUSE OF FAILURE
FATIGUED SOLDER JOINTS DUE TO STRESS ON EXTERIOR SEMI-RIGID LINES.
ALL CENTRE CONDUCTOR CONNECTIONS ON SEMI- RIGID LINES WHERE NOT PRE-TINNED PRIOR TO BEING SOLDERED AT MANUFACTURER, LEADS WERE SOLDERED UNDER STRESS AS EVIDENT FROM LEADS MOVING DURING RE-SOLDERING PROCESS .
LACK OF GOOD MECHANICAL STABILITY ON OUTSIDE PLATE HOLDING BNC CONNECTORS.
NO LOCKING WASHERS USED ON OUTSIDE PLATE TO DETER SCREWS FROM TURNING WHICH IN TURN WOULD CAUSE DE-TUNING OF CAVITIES.
SLIGHT BEND IN FRONT PLATE HOLDING BNC CONNECTORS, LACKS SUPPORT IN CENTRE.

11. CHARACTERISTICS

12. SPECIFICATION SHT 1

13. SPECIFICATION SHT 2