Service manual

RECEIVER NP88 FLEX
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Tuning
Synthesized receivers are tuned to the middle of the bandsplit at the factory for optimal performance across
the band. To ensure optimal performance is maintained,execute the tuning download from the PPS to put the
pager in the middle of the band. This frequency is called the “ tuning frequency” and is different for every
band split.
Alignment Procedure
The NP88 Flex 900MHz pagers is aligned at the factory to provide peak performance over a long
period of time. If alignment is ever required, use the following procedure
1. Turn on the RF circuit: To turn on the RF circuit, short the EC by soldering a wire to both pads.
2. Ensure a battery with a minimum output of 1.5 volts is installed in the pager.
3. Connect the test equipment.
4. Align the pager according to the alignment procedure described below.
Signal generator setup
Frequency = Center frequency of each band
Amplitude signal output = -30dbm
FM encoder = 4.8KHz deviation
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Tuning VCO voltage!
Measure voltage of TP12 by Multi-meter, rotate VC404 by ceramic tuning tool to make the voltage measured
is 1.2V.
Tuning center frequency deviation
Connect probe of scope with frequency counter, put probe on TP3, adjust SG to center frequency and out put
signal from normal Load antenna, then increase signal until 455KHzvalueisshownonfrequencycounter,
indication of GATE on frequency counter will be glitter continuously. Adjust VC5, make frequency counter
value is 455KHz +/-50Hz.
Tuning RF-amplifier
Connect probe of scope with frequency counter, put probe on TP3, adjust SG to center frequency and out put
signal from normal Load antenna, then increase signal until 455KHzvalueisshownonfrequencycounter,
indication of GATE on frequency counter will be glitter continuously. Adjust VC003, make frequency counter
value 455KHz has maximal amplitude.
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Tuning Antenna
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Connect probe of scope with frequency counter, put probe on TP3, adjust SG to center frequency and out put
signal from normal Load antenna, then increase signal until 455KHz value is shown on frequency counter,
indication of GATE on frequency counter will be glitter continuously. Adjust VC004, make frequency counter
value 455 KHz has maximal amplitude.
3-4 June 21, 2004