Operating instructions

LIGHT-WEIGHT DIRECTIONAL POWER HEADS
B-10 46882-311D
B2609
Fig. B-2 Directional Power meter screen (Light-weight DPH)
The power head is now installed and the service monitor ready to make directional power
measurements.
Ensure that the transmitter power is OFF and an antenna or load is connected to the transmitter.
The RF connections should be made so that the signal path from the transmitter to the antenna is in
series, through the power head, in the direction of the arrow on the front panel.
The power head is able to operate in two modes, CW mode for measuring Carrier Wave,
Frequency Modulation or Phase Modulation signals; PEP mode for measuring amplitude
modulation or Single Side Band signals.
Press the [PEP/CW] key to switch between the two modes. The current selection is shown near the
top of the screen.
Set the frequency of the signal to be measured, using the [RF Freq] key and the data keys.
Switch on the transmitter under test. Readings appear on the screen for forward and reverse power
levels and of VSWR. The values appear on the three horizontal barcharts.
Digital readings are also displayed for each of the three values, with a maximum resolution of three
figures. Below 10 mW the power readings are reduced to a single figure, with two figure
resolution up to 99 mW.
The barcharts can be set for autoranging or manual range selection. Repeated presses of the
[Bchart Select] key selects each barchart in turn. The selected barchart is indicated by an  or & at
the left end.
Pressing the [Autorange] key will switch the selected barchart to autoranging, indicated by an .
To change a barchart from autoranging to a specific range, first select the barchart using the
[Bchart Select] key, then press the [] key or [] key, until the required range is selected. If the
barchart was in autorange mode, the first press of a range change key will place the barchart in
’Hold’ mode without changing the range.
The barchart indications of the service monitors power measurement range is covered in 10 ranges.
The lowest range has a maximum indication of 30 mW, with 10 mW and 20 mW divisions. The
highest range has a maximum indication of 1 kW, with 0.2, 0.4, 0.6 and 0.8 kW divisions.
Between these, the ranges continue in a 1, 3, 10 sequence.
The RF power range covered by the Light-weight Directional Power Head depends upon the
frequency of the signal being measured. Refer to the performance data relating to the specific
power head type, for the usable power range.