HP 8648 A/B/C/D - Changpuak.ch

Pager Encoder
Timebase
Frequency
Adjustment
7-6 Adjustments
Use this procedure to adjust the pager encoder timebase frequency.
Required Test w HP 5334B Option 010 Universal Counter
Equipment
Procedure 1. Turn off power to the signal generator.
2. Remove the instrument cover.
3. Connect the MOD INPUT/OUTPUT connector of the signal
generator to the input of the universal counter as shown in
Figure 7-4.
[PUT
UNIVERSAL COUNTER
J
an64abc
Figure 7-4. Pager Encoder Timebase Frequency Adjustment Setup
4.
5.
6.
7.
8.
9.
Turn on power to the signal generator and let it warm up for one
hour.
Enter the pager encoder mode by pressing (FM) (ENCODER)
twice. (If FM was the last active function, only press the
(FM) (ENCODER) key once.)
Rotate the AMPLITUDE/ENCODER knob to set FORMAT to
SERVICE.
Press ($j (NEXT) and rotate the AMPLITUDE/ENCODER knob to
set CALIBRATIONFSK to3200/2.
Press @KKK) (START/STOP) to turn the encoder output on. The
universal counter should now read close to 1600 Hz.
Adjust the variable capacitor on the encoder timebase (labeled
“TIMEBASE ADJUST 1EP” in Figure 7-5) until the frequency on
the universal counter reads 1600 Hz rtO.0016 Hz.