86 Reciter Fault Finding TB8100 Service Manual© Tait Electronics Limited September 20063.9 ExciterThese checks will verify whether:■ the exciter synthesizer is locked■ the exciter output meets the required specifications.Task 1 —Check Synthesizer 1. Set up the test equipment as shown in Figure 3.2 on page 73.2. Run the Service Kit and connect to the reciter. Put the reciter inStandby mode. Select Diagnose > Reciter > Synthesizers.3. Check that the exciter synthesizer is locked. If it is, go to Task 2. Ifit is not, got to Step 4.4. Click Start Test in the exciter row.5. Check that the synthesizer lock range matches the frequenciesdisplayed in the Exciter setting box in the Monitor > ModuleDetails > Reciter form. If the two frequency ranges match, go toTask 2. If they do not match, adjust the exciter lock band using theCalibration Kit and repeat this task.Task 2 —Check ExciterOutput1. Put the reciter in Run Mode and set the TX KEY switch on theCTU to ON.2. Select Diagnose > Reciter > Digital I/O and check that the Tx Keyinput is active (Service Kit “LED” is green). If it is active, go toStep 3. If it is inactive (“LED” is red), return the complete reciter toyour nearest CSO for repair or replacement.3. Use the Service Kit to set up the reciter as a repeater. Inject an RFtest signal (1kHz audio, 60% modulation) of the required frequencyat –80dBm (22.4μV):■ narrow bandwidth 1.5kHz ±125Hz■ mid bandwidth 1 2.4kHz ±200Hz■ wide bandwidth 3kHz ±250Hz4. Check that the performance of the exciter meets the followingspecifications:■ RF output power +11dBm ±2dB (8mW to 20mW)■ deviation 60%■ frequency accuracy ±0.5ppm or ±1ppm.Note All reciters with hardware version 0.03 or later have a frequencystability of 0.5ppm (VCTCXO). Reciters with hardware version0.02 or earlier have a frequency stability of 1ppm (TCXO).1. H band only.
