Ritron RIT13-144 Manuale Utente

1

RITRON surface mount products require special
equipment and servicing techniques. Improper
servicing techniques can cause permanent damage
to the printed circuit boards and/or components,
which is not covered by RITRON’s warranty.  If you
are not completely familiar with surface mounted
component repair techniques, RITRON recommends
that you defer maintenance to qualified service
personnel.

This radio contains complementary metal-oxide
semiconductor (CMOS) devices, which require
special handling techniques.  CMOS circuits are
susceptible to damage by electrostatic or high voltage
charges.  Damage can be latent, with no failure
appearing until weeks or months later.  For this
reason, take special precautions any time you
disassemble the radio.  Follow the precautions below,
which are even more critical in low humidity
environments.

1) Storage/transport - CMOS devices that will be

stored or transported must be placed in
conductive material so that all exposed leads are
shorted together.  CMOS devices must not be
inserted into conventional plastic “snow” or
plastic trays of the type that are used for other
semiconductors.

2) Grounding - All CMOS devices must be placed

on a grounded bench surface.  The technician
that will work on the radio/CMOS circuit must be
grounded before handling the radio.  Normally,
the technician wears a conductive wrist strap in
series with a 100K Ohm resistor to ground.

3) Clothing - Do not wear nylon clothing while

handling CMOS circuits.

4) Power off - Remove power before connecting,

removing or soldering a PC board that contains
CMOS devices.

5) Power/voltage transients - Do not insert or

remove CMOS devices with power applied.
Check all power supplies to be used for testing
CMOS devices, making sure that no voltage
transients are present.

6) Soldering - Use a grounded soldering iron for

soldering CMOS circuitry.

7) Lead-straightening tools - When straightening

CMOS leads, provide ground straps for the tool
used.

RITRON recommends using a knurled nut tool to
remove the slotted knurled nuts that secure the
charge and audio jacks on top of the radio.  You will
need two sizes of this tool, one for each jack size.
Mouser Corporation 

 is one source, stock number

382-0004 (2.5mm jack) and 382-0006 (3.5mm jack).
You can reach Mouser sales and distribution center
at 1-800-346-6873.

The synthesizer shield should not be removed, unless
a component must be replaced.  This shield is
soldered to the main PC board.

The speaker magnet will pick up clipped leads and
other small metal objects from your bench top.  Even
tiny objects on the diaphragm will cause the speaker
to buzz.  Make sure the speaker is free of foreign
objects before reassembling the radio.

The SST-144 was designed to produce 4 Watts of
Transmitter power at nominal battery voltage (+7.2
VDC), throughout the radio’s operating frequency
range.  Measurements are made with the RITRON
SST-SRVBD RF service module connected to the
radio antenna terminal.  The transmitter was
designed with close tolerances to prevent RF power
output from exceeding specifications and reducing
battery life.

Changes in circuit design, component values, and
radio firmware are made occasionally to enhance the
performance of the SST-144. In general, the manual
will be periodically updated for component value
changes without a change in the manual revision
level.  Always refer to the Schematic Reference Parts
List for the most recent component values.  Changes
in circuit design that require printed circuit board
revision, or changes in firmware that significantly alter
the operating characteristics of the radio, will be
covered in a revised manual.

This manual is updated for the following revisions:

SST-144-MRM

Rev A

PCB Revision

1750250C

Firmware Revision

v06