Service manual

25
Functional Description
DCB, DCFCB and DCFCTB Models
Transceiver Interface
A transceiver may be interfaced through the male DB9 connector, P1.
Position
Description
1
Transmit Audio
2
Receive Audio
3
PTT
4
Ground
5
12 VDC (unregulated)
6
Carrier Detect
7
Not used
8,9
Ground
Figure 4 Transceiver Interface Connector P1
Transmit Audio
You can adjust the encoded audio from 0 to 1.2 V
p-p
(O.C.) using the DTMF
Deviation Potentiometer, R71 and Digital Deviation Potentiometer, R70. This is used
to set the audio output level to the transceiver. The transmit audio should be
connected to the radio’s mic (emphasized) audio input and adjusted as follows:
 DTMF – Adjust R71 for 3 kHz deviation (add .75 kHz deviation if CTCSS is
used.)
 Digital – Adjust R70 for 3 kHz Deviation (do not exceed 4 kHz)
*Note: Deviation levels are cut in half when using 12.5 kHz channel spaced radios.
Receive Audio
Connect the receive audio to the radio’s de-emphasized audio out. You can adjust the
audio level of an external transceiver by R48 and when receiving a properly
modulated signal as described above, adjust to 1 V
p-p
at TP8.
PTT
Push-to-talk pulls to ground to place the transceiver into transmit mode.
+12 VDC
The +12 VDC is an unregulated, 1.0 Amp supply that can vary from
11.5 – 13.6 VDC