Kenwood NXR-800 Service Manual page 81

Adjustment 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 Alignment
Test Equipment
1. Frequency Counter
■ Adjustment Setup
The KXK-3 OCXO unit must be mounted on the NXR-700 or NXR-800 repeater. Adjustment setup is shown as follows.
PC
Cross
cable
To adjust the KXK-3 OCXO unit, some preparations are required.
1. The NXR-700 or NXR-800 with the KXK-3 OCXO unit must be warmed up at least 24 hours before the adjustment is made.
The environment temperature must be stable.
2. The frequency counter (or reference oscillator) must be warmed up as defi ned by the equipment manufacturer.
■ Adjustment
Item Condition
1. Setting 1) Connect the DC power output to the rear panel DC terminal (13.8V).
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 cable.
5) Activate the FPU to go to the test mode.
2. OCXO
frequency
adjustment
Note:
Adjusted data is stored in the KXK-3 internal memory, therefore no re-adjustment is required when the adjusted KXK-3 is moved
to another NXR-700 or NXR-800.
ADJUSTMENT
Frequency Range
Resolution
Reference Frequency Accuracy
Input level
D-sub
NXR-700 or REF OUT
9pin terminal
NXR-800
KXK-3
DC power
supply
Measurement
Test-
Unit
equipment
f. counter Rear
Major Specifi cations
Up to 50MHz
9 digits
Smaller than 0.01ppm
Up to 5Vpp
Attenuator Frequency
(if necessary) counter
Adjustment
Terminal Unit Parts
REF PC
OUT ADJ
NXR-800
External
frequency
refernce
(if necessary)
Specifi cations /
Remarks
Method
±0.15ppm
9.99999850MHz~
10.00000150MHz
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