Operating instructions

INSTALLATION
2-11
Test No 15
FM deviation. 50 kHz
This test checks the signal generator FM deviation against the modulation meter reading.
Related set-ups. Frequency 10 MHz, level -26 dBm, IF bandwidth 300 kHz, audio bandwidth
0.3 - 3.4 kHz, FM demodulation.
The functions verified by the above tests are:-
Signal generator FM accuracy, modulation meter FM accuracy, modulation generator (audio
generator) level accuracy.
Test No 16
Modulation frequency. 1 kHz.
This test checks the modulation generator output frequency against the audio counter reading.
Related set-ups. Frequency 10 MHz, level -26 dBm, IF bandwidth 300 kHz, audio bandwidth 0.3
- 3.4 kHz, FM demodulation.
The functions verified by the above tests are:-
Modulation generator (audio generator) frequency accuracy.
Test No 17
AM Depth. 50%
This test checks the signal generator AM against the modulation meter reading.
Related set-ups. Frequency 10 MHz, level -26 dBm, IF bandwidth 0.3 - 3.4 kHz, AM
demodulation.
The functions verified by the above tests are:-
Signal generator AM accuracy, modulation meter AM accuracy, audio generator frequency
accuracy, audio generator level accuracy, audio filters, audio counter.
Positioning the Service Monitor for use
The monitor can be used as a bench instrument, either flat standing or inclined using the elevating
front feet. Refer to the caution relating to Tilt facility in the preface to this manual. The monitor
can also be used as a field service instrument while left in the operational case. It can be operated
in any position convenient to the operator. Note that if the Service Monitor is supplied with the
non-operational soft carrying case that has no ventilation apertures, the Service Monitor must be
removed from the case before operating. See the
Caution under Ventilation in this chapter.
Routine maintenance
Ventilation fan and filter
The ventilator fan on the rear of the Service Monitor is fitted with a filter to prevent the ingress of
foreign matter into it. This should be inspected and cleaned at regular intervals. The procedure
for this is as follows:-
Disconnect the Service Monitor from the mains supply and from any DC supply.
Remove any other connections to the Service Monitor.
WARNING
Failing to disconnect the power source before removing the filter could result in the fan
becoming switched on accidentally.
Stand the Service Monitor face down on a firm, non-scratch flat surface so that it is supported on
the front handles.† The rear of the Service Monitor, with the fan housing, should be at a safe and
accessible working height.
Remove the two M4 screws holding the fan filter to the rear of the Service Monitor and lift the
filter away.
Take the filter to a suitably ventilated location and remove as much dust and other foreign matter
as is practical. Do not wet or wash the filter.
Refit the filter to the Service Monitor, using the reverse procedure as appropriate.
If the filter is damaged or blocked, a replacement is available as part no. 35907/675.
†
If the bail arm carrying handle has been fitted, this should be positioned over the top of
the Service Monitor before standing it face down, supported on the front bumpers.