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
The 2-pin Molex connector is the supply voltage input to the unit. One should be absolutely sure
of the proper voltage and current requirements before applying power.
The DTX-165, DTX-265, DTX-365, and DTX-465 units use 12.5 volt RF Power Modules. The
supply voltage can be at any voltage between 11 and 16 volts. 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 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 (DTX-965)
The current drain of the module is a function of the supply voltage and the RF output in transmit.
Typical current drain values are shown in the table below:
Receive Mode
Supply Voltage
Internal Regulator
Current Drain
11.0 V
Yes
150 mA
12.5 V
Yes
150 mA
16.0 V
Yes
150 mA
