5
OPERATION
5.1
CHANNEL SELECTION
The DTX module supports eight channels. The desired channel is chosen via pins 1, 2, and 3 of the 15 pin
connector as shown:
Channel
Pin 3 (CS2)
Pin 2 (CS1)
Pin 1(CS0)
1
0
0
0
2
0
0
1
3
0
1
0
4
0
1
1
5
1
0
0
6
1
0
1
7
1
1
0
8
1
1
1
0 = Logic low (0 to 0.3 VDC)
1 = Logic high (3.5 to 5.0 VDC or left unconnected)
A logic low is a voltage level below 1 volt while a logic high is a voltage level above 3.5 volts. These three
pins have an internal 10 k pull-up resistor to + 5 volts. Therefore, any pin left unconnected will assume a
logic high state. Do NOT apply voltages outside the range of 0 to +5 volts to these pins. Note: When the
Ritron programming cable is connected, these pins are not connected and thus, assume a logic high state.
Therefore, the radio will be on channel 8 when the Ritron programming cable is connected.
A change in the channel selection in receive will cause the receiver to operate on the new channel. In
transmit, however, the channel selection is only checked upon a push-to-talk activation. Changes in
channel during transmit will not change the transmit operating channel of the unit until the unit is cycled
from transmit to receive and back to transmit.
5.2
POWER SUPPLY VOLTAGE
Pin 6 is the positive supply input to the unit. The type of module determines the actual voltage that should
be applied to this pin. One should be absolutely sure of the proper voltage and current requirements before
applying power.
The DTX-160, DTX-260, DTX-360 units and the 3 and 6-watt DTX-460 units use 7.5 volt RF power
modules. 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 RF power module in the 10 watt DTX-460 unit requires at least 12 volts to
achieve 10 watts, although voltages as high as 15 may be used. Since the module is powered directly from
this voltage, the supply should be “clean” and, preferably, regulated. 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.
