Nautel XR12 Troubleshooting Manual

Also see for XR12: Installation manual Operation and maintenance manual Preinstallation manual

Contents

XR12 Troubleshooting Manual Detailed Circuit DescriptionsIssue 3.0 2009-07-28 Page 2-1Section 2: Detailed Circuit DescriptionsRefer to the functional block diagram: “XR Series Transmitter Block Diagram” on page 1-7 and highlevel descriptions of the XR12 Operation and Maintenance Manual.This section provides a detailed description of the transmitter’s key modules and assemblies,including:• Control/display PWB (NAPC147D) - see page 2-1• RF synthesizer PWB (NAPE70C) - see page 2-4• Interphase PDM driver PWB (NAPM10B) - see page 2-8• Remote interface PWB (NAPI83/01A) - see page 2-13• RF drive (62 V) & fan (48 V) power supply PWB (NAPS30/01) - see page 2-18• RF drive power supply PWB (62 V) (NAPS10B) - see page 2-19• RF power module (NAP34A) - see page 2-20• RF drive buffer PWB (NAPE77A/01) - see page 2-31XR12 electrical schematicsThe descriptions in this section all refer to the XR12 electrical schematics listed in Table 5.1 onpage 5-5 of the XR12 Troubleshooting Manual.Control/display PWB (NAPC147D)See electrical schematics Figures SD-5 through SD-8.Carrier reference voltageThe Carrier Ref (A) output (J7-38) is applied to the interphase PDM driver PWB of each exciter togenerate the PDM drive pulse that ultimately controls the RF output of the transmitter. DAC U31, inconjunction with microcontroller U22, establishes a dc reference voltage for the Carrier Ref output.The voltage is buffered through operational amplifier U27B and associated components.