RF Neulink NL5000-T - Manual (Page 13)

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5 OPERATION
5.1 CHANNEL SELECTION
The NL5000-T 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 Pin 2 Pin 1
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
1 = Logic high
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 kΩ 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.
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.
Three voltages are used within the unit; +5 volts for the processor and logic circuits along with
most of the receiver, +7.5 volts for the transmitter driver stages, and the supply voltage for the RF
power module which depends upon which module is used.
The VHF and 220 MHz units and the 3 and 6-watt UHF 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 10 and about 15 volts. Although the use of the
regulator allows flexibility in terms of supply voltage, because of the amount of heat generated by
the regulator, significant duty cycle/key down limitations may apply (see below).