5
OPERATION
5.1
CHANNEL SELECTION
The DTXM module supports four channels. The desired channel is selected from RS-232
communication. Radio defaults to Channel 1 with no connection.
5.2
POWER SUPPLY VOLTAGE
The DTXM-460 unit uses a 7.5 volt RF power module. Two supply voltage options are available
for these units depending upon whether the control/loader board has a regulator installed. If a
regulator is not installed, the voltage should be 7.5 volts +/-
10 %. This voltage should be “clean”
and preferably regulated since the RF power module is powered directly from this source.
Variations in voltage will cause variations in transmitted output power. Conversely, if the
control/loader board has a regulator installed, the supply voltage can be at any voltage between
11 and 16 volts. The output power will vary with supply voltage. Switching power supplies can
be used, but in models without the internal regulator, care must be taken that the output
waveform is low noise. Also, the module antenna should never be placed near an unshielded
switching power supply.
5.3
CURRENT DRAIN VS SUPPLY VOLTAGE
The current drain of the module is a function of the supply voltage, the RF output in transmit and
the regulator option. The internal 7.5-volt regulator is a switching type such that the current drain
actually decreases with an increase in supply voltage. Typical current drain values are shown in
the table below:
Receive Mode
Supply Voltage
Internal Regulator
Current Drain
7.5 V
No
130 mA
11.0 V
Yes
100 mA
12.5 V
Yes
90 mA
16.0 V
Yes
75 mA
Transmit Mode
– 1 watt output power
Supply Voltage
Internal Regulator
Current Drain
7.5 V
No
1.2 A
11.0 V
Yes
0.9 A
12.5 V
Yes
0.7 A
16.0 V
Yes
0.5 A
Warning: Although the output power can be set as low as 1 watt, and the module is
certified as low as 1 watt, operation below 2.5 watts output power is not recommended. At
low power levels, the output power can vary by 50% or more with variations in ambient
temperature.
Transmit Mode
– 3 watt output power
Supply Voltage
Internal Regulator
Current Drain
7.5 V
No
1.8 A
11.0 V
Yes
1.4 A
12.5 V
Yes
1.2 A
16.0 V
Yes
0.9 A
Transmit Mode
– 6 watt output power
Supply Voltage
Internal Regulator
Current Drain
7.5 V
No
2.5 A
11.0 V
Yes
2.1 A
12.5 V
Yes
2.0 A
16.0 V
Yes
1.5 A
