Specifications

EQUIPMENT REQUIRED
The following equipment and software may be required
to modify and configure the CNI GETC:
IBM compatible PC with at least 640K memory,
monitor, and keyboard.
• Hard disk is recommended; but, not required.
• Serial Port configured as either COM1 or COM2.
• TQ-3360 programming cable.
• Male DB-25 to female DB-9 adapter.
• Software distribution diskette 344A4414.
• Oscilloscope.
• Standard hard tools.
• Temperature controlled soldering station.
HARDWARE INSTALLATION
Typically, a CNI GETC is installed in the repeater
cabinet, just above the repeater’s radio assembly, using
hardware kit 19A130031G30. The tray containing the sub-
assemblies is mounted within a slide out shelf measuring
1.75 inches high (one rack unit) by 19 inches wide.
Install the GETC Shelf into the repeater cabinet, refer to
the MASTR II, IIe, or MASTR III Application Assembly
and Installation Diagrams for detailed information on
installing the GETC Shelf. Installation or removal of the
shelf sub-assemblies involves sliding the GETC tray out of
the cabinet and into the service position. This position
allows access to the shelf’s sub-assemblies.
Observe basic safety precautions to prevent injury or
equipment damage.
Logic Board Modification
The following steps provide instructions for modifying
the GETC Logic Board. Materials for this modification are
provided in Hardware Kits 344A3845 and 344A4019. For
additional GETC assembly and maintenance information,
refer to LBI-38894 and LBI-38988.
1. Place the GETC shelf in the service position.
2. Disconnect all cables from the GETC Logic Board.
3. Remove the GETC Logic Board 19D904266 from
the shelf. Refer to the GETC Service Manual LBI-
38894 for detailed instructions for removing and
installing the printed circuit board in the GETC
shelf.
4. Solder an orange wire jumper 19A115663P4 (part
of Hardware Kit 344A4019) from TP107 to J7-7.
Route the wire as shown in Figure 4. This allows
access to the test point which will be covered by
the Turbo Board installation.
5. Solder the white wire 19A115871P22 (part of
Hardware Kit 344A3845) between TP102 and J18-
2 as shown in Figure 4. This essentially connects
the output of the Low Speed Decode Filter to U1’s
interrupt line, INT0 as shown in Figure 3.
6. Reinstall the Logic Board into the GETC Shelf
using the installation instructions provided in LBI-
38894. Omit the three (3) screws on the J3 end of
the board (these will be used to secure the Turbo
Board).
The modified circuit functions as follows:
The conventional received audio (VOL/SQ HI) enters
the GETC at J7-2. This audio includes sub-audible signals
that represents the Channel Guard tone information. The
Low Speed Decode Filter removes the received audio and
routes the Channel Guard tone information to U1, the
GETC’s main processor.
The standard parallel input at U1-3 is unused in the CNI
configuration. Instead, U1 processes the Channel Guard
tone information using the interrupt line at U1-12. The CNI
application also requires a jumper from J18 pin 1 to pin 2.
The CNI uses the signal at INT0 to convert a
conventional transmission with Channel Guard tone
information into a digital EDACS message representing
Group Call Assignments. This process results in the
CEC/IMC seeing a normal EDACS Group Call channel
assignment message based on the sub-audible Channel
Guard tone information embedded in a conventional
transmission.
Observe precautions
for handling
ELECTROSTATIC
SENSITIVE DEVICES
CAUTION
Do Not install the jumper wire between TP107 and J7-
7 when the CNI GETC is used in MASTR III
repeaters. If the wire was previously installed,
disconnect it from J7-7.
NOTE
LBI-38986
7