User's Manual

3 CS2-Most significant bit of the channel select lines. Active high 5 volt TTL/CMOS
level. Internal 10 k pull-up to +5 volts.
Channel CS2 CS1 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
1 = Logic high
Note: Due to the internal pull-up resistors, the unit defaults to channel 8 if the channel
pins are left open (unconnected). Channel 8 would be the nominal channel when the
Ritron programmer is connected.
4 MIC IN-Microphone input. This input accepts microphone-type input signals for
transmit. This input is a higher gain version of the AUX IN input. This input is not
available in very narrow channel mode.
5 CSN-Depending upon how it is programmed, this input selects between channels 1 and 2
or between high and low RF output power. This input is TTL/CMOS level type input
with a logic low required for channel 1/low power and a logic high required for channel
2/high power. Internal 10 k pull-up to +5 volts.
6 NO CONNECTION.
7 AUX IN-This is the main audio input for modulation. The gain through this input to the
modulator is programmable, as is the use of pre-emphasis, but not independently of the
MIC IN. This signal passes through the clipper and clipper filter.
8 AUX OUT-This is the broadband output of the receiver. The gain from the receiver to
the output is programmable, as is the use of de-emphasis. The choice of AC or DC
coupling from the RF board discriminator is also programmable. The coupling at the
output of this pin is AC coupled, however. It can be converted to DC coupling with
internal hardware modifications. Note: The output impedance is approximately 600
ohms. Therefore, it is not recommended that this output drive loads with less than
1000 ohms unless the resultant voltage drop is accounted for.
9 PGN IN/OUT-Connect via RITRON DTXP-PCPK PC Programming Kit to computer for
programming the unit.
10 CTS-Clear-To-Send output from the unit which indicates that the unit is transmitting a
carrier at the correct frequency and power level and is ready to accept an input signal to
be transmitted. This output would normally become asserted in response to a PTT RTS
(see pin 14 description below) activation. The polarity of this output can be programmed.
The output is active low 5 volt logic with an internal 10 k ohm pull-up to 5 volts. It can
source up to 10 mA when low.
11 RX MON-This input breaks the squelch (unmutes) on the receiver i.e. allows for
monitoring the channel even when a signal not strong enough to break squelch is present.
Input levels are TTL/CMOS; polarity may be programmed. Internal 10 k pull-up to +5
volts.