Fitting the Options SMIQ
1125.5555.03 E-71.6
Set tuning voltage and
calibrate OCXO
The crystal oscillator was factory-tuned to nominal frequency and the
appropriate tuning voltage indicated on the cover of the module. The
calibration value now has to be calculated from this value and
transferred to the memory of the signal generator.
Calculate calibration value The tuning voltage is generated by a 12b-bit-D/A converter which is
scaled such that a tuning voltage of 12 volts is generated with
calibration value (CALIBRATION DATA) 4000.
The calibration value is thus calculated from the tuning voltage (V
tun
)
as follows
CALIBRATION DATA = V
tun
× 4000 / 12
For checking purposes, the voltage at pin 16 of plug X22 on the
motherboard can be remeasured and corrected if necessary. A check
by means of frequency measurement may only be made after a
warm-up of 2 hours and against a calibrated reference.
Store calibration value
½ Unlock protection level 2 with code 250751.
v Call menu UTILITIES-CALIB-REF OSC.
½ Enter the calculated calibration voltage with CALIBRATION DATA
by means of the rotary knob or keypad.
½ Select STORE CALIBRATION DATA
½ Terminate entry using the [SELECT] key
The new calibration value is stored in the EPROM.
Note: The flash EPROM does not permit the deletion of individual
data. Thus new memory space is occupied for each calibration.
If there is no memory space available any more, the EPROM
must be cleared by an authorized service shop and be written
into anew. Thus a calibration should only be made if necessary
1.3.4 Option SM-B5 - FM/PM Modulator
The FM/PM modulator is fitted at the slot with label 'FMOD'.
Fitting the option
½ Withdraw cable W89 from X99 of the summing loop and use again.
½ Establish the following connections:
Cable From To Signal
W89 A8-X89 A6-X67 FDSYN
W65 A6-X65 A7-X71 REF100
W67 A6-X69 A9-X99 FDFM
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