Operating instructions

OPERATING MANUAL 2945A
46882-311D 3-25
shape settings of their last use in the Rx TEST mode will be retained within the
Rx TEST mode setup. These settings will be effective when the generators are
switched to the ‘ON’ condition in receiver test mode. Their use as audio
generators in the Tx TEST mode will then be disabled.
Pressing the [Lock] key locks the output level of the two audio generators to the same level. The
unselected generator locks to the level of the selected generator.
When the audio generators are set to the required settings press the [Return] key to restore the Tx
TEST menu.
Making measurements
This section describes the actions needed to make measurements of each parameter associated
with transmitter testing. All tests are described individually as ‘one off’ tests, but in practice,
once set up, all active parameters will be measured simultaneously with continuous updating and
the results displayed using the selected measurement units.
The results obtained from tests can be stored for later analysis or transfer to hard copy by making
use of the internal setup/results memories or the optional memory card facility. Test mode screen
settings can similarly be stored for future use.
All of these features are described under
Stores, Settings/results, or Printer, later in the
chapter.
Transmitter power
Broad Band and Narrow Band power measurements
The monitor has both Broad Band and Narrow Band power measurement facilities. The Broad
Band power meter measures the total average power of all signals present at either RF input,
while the Narrow Band power meter measures only the average power of the signal contained
within the IF pass band selected for the Tx TEST mode.
The facilities of the Service Monitor allow the RF signal generator to remain active in the Tx
TEST mode. Therefore the signal from this will be present at common points within the RF
input/output circuits of the instrument and will contribute to measurements made by the power
meters. When making measurements where this will make any significant difference to the
measurement, disable the RF generator by selecting the
RF Gen OFF condition from the Rx
TEST mode or the Dx TEST mode.
Narrow band power measurements cannot be made when the frequency of a transmitter has been
set using the [Auto Tune] key.
The maximum continuous power rating of the ‘N-Type’ connector is 50 W with a minimum
indication of 5 mW. Lower levels of input signal are indicated as voltage levels, the first bar
chart graduation being at 20 µV. The maximum continuous power rating of the antenna BNC
connector is 5 W.
A power overload condition is indicated by an audible and visual warning. Should this
condition be indicated, immediately reduce the level of RF power from the transmitter into
the Service Monitor.
Do not stop the warning by switching off the Service Monitor, as this will silence the
warning but will leave the excessive RF power connected to the internal load.
Do not attempt to stop the warning by disconnecting the RF connector, as this can damage
the transmitter and may cause electric shock or skin burns.