CPI Communications DTP Series - Manual (Page 2)

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General Information
The CPI Communications DTP series DC remote adapters provide a reliable means of remotely controlling
a two-way radio base station or repeater over in-house or leased metallic pair wiring.
The DTP series can be used with CPI DC remotes as well as most other manufacturers DC remote consoles.
The DTP remote adapters are available in the following variations, all of which provide adjustable RX and
TX amplification and dip switch selection of control current format:
MODEL DESCRIPTION
DTP1 Board only product, provides PTT.
DTP2 Board only product, provides PTT and monitor functions.
DTP3 Board only product, provides PTT, monitor, F1/F2 functions.
Installation
Connect the leased or in-house metallic twisted-pair 600 ohm line, to the DTP board via J2. (the RJ-11 jack)
Connect an external 12 to 16 volt semi-regulated DC power supply to J1 with the positive lead to J1-2 and
the negative lead to J1-7.
Connect the radio receiver audio output to J1-6. Radio receiver audio output should be a source that is after
the squelch circuit and not affected by the radio's volume control adjustment. If a squelched audio source is not
available there is a squelch circuit provided on the DTP series termination panels. J1-5 is the input to the DTP's
squelch circuit. It can be configured active high or active low using jumpers JU14 and JU15.
Connect the radio microphone input to J1-1. If microphone input is high-impedance, shielded cable should
be used and R65 on the DTP board should be clipped. If a local microphone is used the mic high should be
connected to J1-3.
If you have a DTP2, connect the monitor circuit of the radio to the DTP2 board using the form "C" relay
contacts at J1-8, J1-9, and J1-10.
Connect the radio PTT circuit to the DTP at J1-4. For radios that key to a positive voltage instead of ground,
the PTT circuit can be altered using JU1 and JU2.
The DTP3 provides a form "C" set of relay contacts at J1-12, J1-13, and J1-14 for two channel frequency
selection. The relay output is factory set to be momentary. This can be changed to latching by using JU-16. The
DTP1 and DTP2 do not provide these contacts.
Level Adjustments
The following level adjustments are normally required only at the time of installation.
1. RX Audio Adjustment
R57 controls the RX audio level to the phone line. With the phone line connected at J2, connect a RMS
voltmeter to the leads of R61 and R62. Unsquelch the receiver so that continuous noise is present and adjust
potentiometer R57 for 0 dBm or 0.8 V rms on the meter.
2. TX MOD Adjustment
This section assumes that each remote in the system has been set to provide an average voice audio level
of 0 dBm as measured at the DTP panel.
Have someone at the remote control console depress and hold the PTT switch. With a voice coming from
the remote, adjust R47 to provide proper transmitter deviation.