Kenwood NXR-700H Service Manual

NXR-700H130Adjustment for KXK-3 (OCXO unit)We recommend that the frequency adjustment be checked each time the radio is serviced, or at least once per year.Maintenance should only be performed under normal temperatures.■ Test Equipment Required for AlignmentTest Equipment Major Specifications1. Frequency Counter Frequency Range Up to 50MHzResolution 9 digitsReference Frequency Accuracy Smaller than 0.01ppmInput level Up to 5Vpp■ Adjustment SetupThe KXK-3 OCXO unit must be mounted on the NXR-700H or NXR-800H repeater. Adjustment setup is shown as follows.KXK-3PCNXR-700H orNXR-800HCross-wiredcableREF OUTterminalD-sub9pin Attenuator(if necessary)DC powersupplyFrequencycounterExternalfrequencyrefernce(if necessary)To adjust the KXK-3 OCXO unit, some preparations are required.1. The NXR-700H or NXR-800H with the KXK-3 OCXO unit must be warmed up at least 24 hours before the adjustment ismade.The environment temperature must be stable.2. The frequency counter (or reference oscillator) must be warmed up as defined by the equipment manufacturer.■ AdjustmentItem ConditionMeasurement Adjustment Specifications /RemarksTest-equipment Unit Terminal Unit Parts Method1. Setting 1) Connect the DC power output to the rear panel DC terminal (13.2V).2) Connect the “REF OUT” terminal to the frequency counter.3) Warm-up the equipment and KXK-3 properly.4) Connect the front panel COM port (D-sub 9 connector) to the PC serial port with a cross-wired cable.5) Activate the FPU to go to the test mode.2. OCXOfrequencyadjustmentf. counter Rear REFOUTPCADJ±0.15ppm9.99999850MHz~10.00000150MHzNote:Adjusted data is stored in the KXK-3 internal memory, therefore no re-adjustment is required when the adjusted KXK-3 is movedto another NXR-700H or NXR-800H.ADJUSTMENT