Nautel XR12 Operation And Maintenance Manual

Also see for XR12: Installation manual Troubleshooting manual Preinstallation manual

XR12 Operations and Maintenance Manual DescriptionPage 1-2 Issue 3.1 2013-03-14The rectifier output is also applied to the B+ distribution PWB, which then provides the B+ voltageto the RF power module and LVPS power supplies, and a B+ sample to the exciter interface PWB.Voltages from the low voltage power supplies are then supplied throughout the transmitter.Ac power transformerThe XR12’s power transformer can be set to use a range of input voltages. See Section 3, “Installingthe power transformer” on page 3-1 in the XR12 Installation Manual.Exciter stageSee electrical schematics SD-1, SD-2 and SD-3 and Figure 1.1 on page 1-3. The exciter stage consistsof an exciter interface PWB (A2A1), RF synthesizer PWBs A (A2A2) and B (A2A4), interphase PDMdriver PWBs A (A2A3) and B (A2A5), distribution PWB (A16), and RF drive buffer PWB (A24). Theexciter stage contains two independent exciter sections (A and B), which can be selected automaticallyor by local or remote control.Exciter Interface PWBThe exciter interface PWB (A2A1) accepts audio from the remote interface PWB, carrier reference,exciter selection, reset, and inhibit controls from the control/monitor stage. It also receives low-level,regulated dc voltages and a B+ sample from the ac/dc power stage, and a sample of the PA voltsfrom the RF power stage. Each exciter section generates its own RF frequency source, PDM anddigital control signals, for use in the RF power stage. The exciter interface PWB passes signals to theRF drive buffer PWB, which then outputs the RF drive signals to the RF power module in the RFpower stageThe exciter interface PWB also provides physical interconnection for the RF synthesizer PWBs (Aand B), and interphase PDM driver PWBs (A and B).