LOCAL OPERATION
3-32
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. 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.
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