GME TX3550S User manual

Compact fully featured 5 watt UHF CB radio
with ergonomic speaker control mic
ScanSuite
faster, smarter scanning
™
INSTRUCTION MANUAL

PAGE 2 INSTRUCTION MANUAL TX3550S
CONTENTS
ACCESSORIES SUPPLIED................................................... 3
INTRODUCTION ............................................................... 3
IMPORTANT INORMATION................................................ 3
Possible issues ........................................................ 3
Emergency channels .............................................. 4
Telemetry Channels................................................. 4
FEATURES ........................................................................ 4
GENERAL OPERATION...................................................... 6
Front panel............................................................. 6
Rear panel.............................................................. 6
Controller microphone ............................................ 7
Controller microphone LCD panel............................ 7
Keypad Functions.................................................... 8
On/Off.................................................................... 9
Volume................................................................... 9
Selecting Channels.................................................. 9
Squelch .................................................................. 9
Signal Meter........................................................... 9
Transmitting............................................................ 9
Time-out timer...................................................... 10
Backlighting ......................................................... 10
Bandwidth filter settings ....................................... 11
Dynamic volume control (dvc) ............................... 11
Voice scrambler .................................................... 12
Beep tone volume................................................. 12
Disabling the internal speaker ............................... 12
Microphone gain .................................................. 12
Silent Squelch TAIL................................................ 13
Repeaters and Duplex Mode ................................. 13
Priority Channel.................................................... 14
Scanning .............................................................. 14
Scan Groups ......................................................... 15
Open scan ............................................................ 15
Group Scan........................................................... 16
Network scan (Net-Scan) ...................................... 17
CTCSS and DCS .................................................... 19
Selective calling ................................................... 21
Using selcall ......................................................... 21
Responding to a selcall alert ................................. 23
Quiet mode .......................................................... 23
Group calling........................................................ 25
Receive-only channels........................................... 26
Configuration menu.............................................. 30
INSTALLATION ............................................................... 31
General ................................................................ 31
Installation ........................................................... 31
DC power connection............................................ 32
ANTENNA CONNECTION ............................................... 33
NOISE SUPPRESSION...................................................... 33
Wiring .................................................................. 33
CTCSS Tone frequency Chart ................................. 34
DSC Tone Chart .................................................... 35
UHF CB Operating Frequencies.............................. 36
SPECIFICATIONS ............................................................ 37
STANDARD COMMUNICATIONS CONTRACT WARRANTY
AGAINST DEFECTS ......................................................... 38

TX3550S INSTRUCTION MANUAL PAGE 3
INTRODUCTION
Your GME TX3550S 80 channel radio is Australian designed
and built and is the most advanced UHF Citizen Band
radio available. It combines the very latest in electronic
hardware with the most up-to-date computer aided design
and manufacturing techniques to produce an extremely
compact mobile radio with outstanding specifications and
performance.
Your radio is designed for unobtrusive mounting in modern
vehicles. With its built-in loud speaker and extremely small
size, it can be mounted in almost any convenient location.
IMPORTANT INFORMATION
CONCERNING UHF CB RADIO
The use of the Citizen Band radio service is licensed in
Australia by the ACMA Radio communications (Citizens
Band Radio Station Class Licence and in New Zealand by
the Ministry of Economic Development New Zealand (MED).
A General User Radio Licence for Citizens Band radio
and operation is subject to conditions contained in those
licences.
The class licence for users and equipment operating in the
CB/PRS 477 MHz band has been amended. This radio meets
the new 80 channel standard.
In simple terms the same amount of spectrum is available;
however, radio transceivers can now operate in a narrower
bandwidth and hence use less spectrum. These radios are
generally referred to as narrowband or 12.5 kHz radios.
By using 12.5 kHz channel spacing instead of 25 kHz, the
40 channels originally allocated can now be expanded to 80
channels thereby doubling the channel capacity and relieving
congestion in the UHF CB/PRS band.
Original 40 channel wideband Radios will continue to
operate on the original 40 channels, however they will not be
able to converse on the newer channels 41 – 80. The newer
narrowband radios will be able to converse with all older 40
channel wideband radios on all channels 1 to 40 as well as
the newer channels allocated from 41 to 80.
The mixing of narrowband and wideband radios in the same
spectrum can cause some possible operating issues
of interference and varying levels of received volume.
POSSIBLE ISSUES
When a new narrowband radio receives a transmission
from an older wideband radio the speech may sound loud
and distorted – simply adjust your radio volume for best
performance.
When an older wideband radio receives a signal from a new
narrowband radio, the speech may sound quiet – simply
adjust your radio volume for best performance.
Depending on how close your receiving radio is to another
transmitting radio, there can be interference from the
transmitting radio if it is using a channel adjacent to the
channel you are listening to. Simply try going up or down a
few channels from the currently selected channel.
The above situations are not a fault of the radio but a symptom
of operating wideband and narrowband radios in the same
bandwidth. This possible interference will decrease over time
as the population of wideband radios ages and decreases.
Further information and updates are available from the
Australian Communications and Media Authority (ACMA)
at www.acma.gov.au and the Ministry of Economic
Development (MED), Radio Spectrum Management at:
www.rsm.govt.nz
ACCESSORIES SUPPLIED
TX3550S 5 watt UHF CB Radio
Mounting Cradle
Controller Microphone
Microphone Clip
DC Lead
Screw Pack
Instruction Manual

PAGE 4 INSTRUCTION MANUAL TX3550S
EMERGENCY CHANNELS
The ACMA has allocated channels 5/35 for emergency use
only. Channel 5 is the primary Simplex Emergency Channel.
Where a Channel 5 repeater is available, you should select
Duplex on CH 5.
NOTE: Channel 35 is the input channel for the Channel 5
repeater therefore Channel 35 should also not be used for
anything other than emergency transmissions.
TELEMETRY CHANNELS
ACMA regulations have allocated channels 22 and 23
for telemetry only applications and have prohibited the
transmission of speech on these channels. Consequently your
radio has a transmit inhibit applied to channels 22 and 23.
In the event additional telemetry/telecommand channels are
approved by the ACMA, these channels shall be added to
those currently listed where voice transmission is inhibited.
Currently transmissions on channels 61, 62 and 63 are also
inhibited and these channels are reserved for future allocation
FEATURES
TRANSMIT (TX)
Individually Programmable DUPLEX Function: User selectable for only those individual channels in your area
that have repeaters, leaving the others free for use as extra simplex channels.
RECEIVE (RX)
Silent Squelch Tail:Eliminates the Squelch noise burst normally audible when the Squelch closes
User Programmable Receive Channels: 95
Signal Receive Indicator: Confirms that an incoming signal is being received
SCANNING AND MEMORY FUNCTIONS
Microprocessor Controlled Frequency Synthesiser: Allows user programmable control of scanning, channel
memories and selected feature options.
Programmable Scan Function
:Scans the selected UHF CB channels with Group, Open and Network scan
functions available.
Priority Channel: A user programmable Priority channel feature allows your working channel to be instantly recalled
at the press of a key.
SIGNAL PROCESSING
Digital Signal Processing:
Measures, filters and compresses standard analogue audio signals and converts them into
digital format. Allows advanced RF and audio processing techniques to be applied to maximise the radio’s performance.
Advanced Signal Management: Identifies interference caused by strong local signals on adjacent channels and
prevents these from opening your Squelch. ASM also minimises distortion on reception by fine tuning the receiver
frequency to match that of the incoming signal.
Dynamic Volume Control: Automatically compensates for variations in received audio level to provide a constant
audio output level to the speaker.

TX3550S INSTRUCTION MANUAL PAGE 5
User Selectable Wide/Narrow Band Filter: To accommodate the blending of 80 channel narrow band radios with
older 40 channel wideband radios.
PRIVACY FUNCTIONS
Voice Inversion Scrambler: When activated, scrambles your voice so that communications are only intelligible to
others using the same scrambler technology.
Inbuilt CTCSS & DCS: User selectable Continuous Tone Coded Squelch System and Digital Coded Squelch system
provides silent operation on individual channels.
In-Built SelCall with Quiet Mode: Provides selective calling of individuals or groups with fully user-adjustable
5-tone transmitted SelCall Ident. Also allows alphanumeric naming of up to 10 Idents for easier caller identification.
PHYSICAL PROPERTIES
Over Voltage Protection: Special overvoltage detection circuitry protects the radio and warns of excessive voltage
conditions by flashing the display.
Rugged Construction: With Die-cast Chassis
USER CONTROLS AND INTERFACE
Full Spectrum Backlighting: User adjustable, totally customisable backlight settings to match the vehicles
dashboard lighting or drivers preference.
High Contrast Liquid Crystal Display: Fully detailed LCD provides a visual indication of the selected channel and
all selected functions at a glance.
Front and Rear Microphone Inputs: Convenient front and rear microphone inputs to facilitate ease of installation
and operation across a range of vehicles.
Digital Signal Strength Meter: Provides a numeric signal strength indication in numbers from 0 to 9+
Full Function LCD Controller Microphone: with rear mounted speaker using ‘Sound Path’™ technology to
channel clear audio towards the user.
A more detailed description of these key functions is included overleaf. These instructions describe the radio functions using the
controller mic.

PAGE 6 INSTRUCTION MANUAL TX3550S
GENERAL OPERATION
FRONT PANEL
DC Power Socket Speaker Socket Antenna Socket Rear Microphone Socket
REAR PANEL

TX3550S INSTRUCTION MANUAL PAGE 7
REAR PANEL CONTROLLER MICROPHONE
Skip/Call
CONTROLLER LCD PANEL
Quiet Tag
Channel Display
Transmit
Busy
SelCall RX
Scan
SelCall/Alpha Display/Signal Meter/Battery Quiet CTCSS/DCS
SelCall TX
Repeater (Duplex)
LEVEL
Channel Up
Push-To-Talk (PTT) Skip/Call
Channel Down
Menu/
F Key
Power Key/
Monitor
Quiet/
Duplex
Squelch/
ALPHA
SCAN/
OS/GS
Squelch level/
Priority channel
Microphone
Volume Up
Volume Down
LCD Display

PAGE 8 INSTRUCTION MANUAL TX3550S
KEYPAD FUNCTIONS
Many of the keys on the TX3540S controller microphone have
multiple functions. The primary functions are labelled in black,
while the secondary functions are labelled in red. To access a
primary function simply press the required key.
To access a secondary function, briefly press the F key
followed immediately by the required key.
The table below shows the control functions for all models.
TX3550S FUNCTION
Press and hold MENU to access the configuration menu. Press F
followed by the required key to access the secondary key-functions labelled in red .
Press SCAN to toggle scanning on or off. Press F followed by OS/GS to select Open Scan,
Group Scan or Network Scan.
Press and hold QUIET to tag the selected channel for use with SelCall. Press QUIET briefly
to toggle the quiet mode on all channels that have been tagged. Press F followed by DUP to
toggle duplex mode on or off on the selected channel.
Press SQL briefly to toggle the Squelch on or off. Press and hold SQL to toggle CTCSS/DCS
silent mode on or off on the selected channel. Press F followed by ALPHA to toggle Alpha or
Numeric display modes.
Press or to change channels.
+
–
Press the + or - keys to adjust the volume.
LEVEL
Press the the LEVEL key briefly to adjust the preset Squelch level. Press F followed by the PRI
key to recall the Priority channel.
Press
F then press and hold the PRI key to store the current channel as the Priority channel.
Press the key to switch the radio on or off.

TX3550S INSTRUCTION MANUAL PAGE 9
NOTE: When using the Fkey to access other functions, Fis
displayed to indicate that ‘Function’ mode is activated. If the
required function is not selected within 6 seconds the Fkey
selection will time out with a low beep and Fwill disappear
from the display.
ON/OFF
Press the
key to turn the radio on. Press and hold the
key to turn the radio off.
VOLUME
Press the +or –key to adjust the volume. Press +to increase
the volume, –to decrease the volume.
If no sound is heard, briefly press the SQL key to temporarily
un-mute the radio then adjust the Volume while listening to
the background noise. When finished, briefly press the SQL
key again to re-mute the radio.
NOTE: At the minimum volume setting there is still sufficient
volume to be heard in a quiet cabin environment.
SELECTING CHANNELS
To select the required channel, press the or key. Press
to select a higher channel. Press to select a lower
channel. The selected channel is displayed on the LCD.
SQUELCH
The Squelch is used to eliminate any annoying background
noise when there are no signals present. The Squelch can
be opened or closed using the SQL key. When the Squelch
is open the receiver’s background noise can be heard and
the symbol is displayed. When the Squelch is closed the
receiver remains quiet while there are no signals present but
any incoming signals will override the Squelch and be heard
in the speaker.
Adjusting the Squelch level
The Squelch sensitivity level has been factory set to provide
optimum performance under most operating conditions. If
required, the sensitivity level can be adjusted to suit
changing conditions.
To adjust the Squelch sensitivity, briefly press the LEVEL
key. The display will show the current Squelch level setting
in values from SQL-1 to SQL-9. Press the or key to
change the Squelch setting. A Squelch setting of SQL-1
allows the Squelch to open on very weak signals whereas a
setting of SQL-9 requires much stronger signals to overcome
the Squelch. After adjusting the Squelch sensitivity, briefly
press the LEVEL key to return to normal operation.
NOTE: The Squelch level can be actively adjusted while the
radio is scanning. This allows you to tighten the Squelch in
cases where an undesired weak or noisy signal is interrupting
the scan.
SIGNAL METER
The signal meter indicates the relative strength of the
incoming signal in numerical format. Signal strengths are
displayed on the lower left of the Channel Display in values
from 0 to 9. Signals above strength 9 are displayed as 9+.
NOTE: Refer to the Configuration Menu for other options
that can be displayed in this location.
TRANSMITTING
Prior to transmitting, always check the channel is not being
used. This can be done by listening to the channel or by
visually checking that the icon is not visible or the signal
meter is not indicating a signal.
To transmit, press the PTT on the microphone. The icon
will appear. Hold the microphone about 3-5 cm from your

PAGE 10 I NSTRUCTION MANUAL TX3550S
face and speak at a normal voice level. The microphone is
quite sensitive so it is not necessary to raise your voice or
shout. Release the PTT when you have finished talking. The
icon will disappear.
IMPORTANT: Always listen to ensure the channel is free
before transmitting.
TIME-OUT TIMER
The radio has a built-in time-out timer that automatically
limits transmissions to a maximum of 3 minutes of
continuous operation. This feature is required by the ACMA to
prevent accidental blocking of the frequency should your PTT
become jammed or be otherwise pressed accidentally. The
time-out period can be changed by your dealer.
When the time-out timer activates, the radio will beep for 5
seconds then the symbol will flash continuously. Normal
operation will be restored once the PTT is released.
BACKLIGHTING
The Liquid Crystal Display and keys are backlit for easier
viewing at night. The backlight remains on whenever the
radio is switched on.
Adjusting the Backlighting
The backlight brightness and colour can be adjusted for
personal preference. There are three backlight settings
available.
BKLGT (Brightness setting): Provides a continuously
variable brightness adjustment from very dim to full
brightness.
COLOR (Colour setting): Provides a continuously variable
adjustment through the full colour spectrum.
White (Whiteness setting): Controls the colour
saturation of the selected colour from deep colour to white
(no colour).
To adjust the backlighting;
1. Hold the LEVEL key to select the Backlight mode. ‘BKLGT’
is displayed.
2. Press or key to adjust the brightness.
3. Briefly press the LEVEL key to select the Colour setting
mode. ‘COLOR’ is displayed.
4. Press or key to adjust the colour.
5. Briefly press the LEVEL key to select the Whiteness setting
mode. ‘WHITE’ is displayed.
6. Press the or key to adjust the colour saturation. For
the deepest colour range, reduce the WHITE setting.
To exit, press and hold the LEVEL key.
Auto-colour Mode
The radio has an automatic colour-change option that, when
activated, will cause the display colour to automatically cycle
through the available colour spectrum. The colour-change
option can be enabled temporarily as an aid to choosing
a display colour or can be set to cycle continuously as the
preferred display colour setting.
To enable the auto-colour option,
7. Hold the LEVEL key to select the Backlight mode. ‘BKLGT’
is displayed.
8. Briefly press the LEVEL key to select the Colour setting
mode. ‘COLOR’ is displayed.
9. While in the colour setting mode, briefly press the MENU
key to enable or disable the auto-colour option. When
enabled, the display lighting will continuously cycle
through the available colour spectrum. When disabled the
display will hold the last selected colour.
To exit, press and hold the LEVEL key. If auto-colour is still
enabled, the display lighting will continue to cycle through
the colour spectrum until disabled using the steps above.
NOTE: The back-light setting function will automatically
time out after 6 seconds if no further adjustments have
been made.

TX3550S INSTRUCTION MANUAL PAGE 11
BANDWIDTH FILTER SETTINGS
To accommodate the blending of newer 80 channel
narrowband UHF radios with the original 40 channel
wideband radios, your radio has been fitted with two user
selectable receiver bandwidth filters. While the use of
either filter will provide superb receive audio, selecting the
wideband filter while on channels 1-40 will further increase
your receiver’s tolerance to older 40 channel wideband
radios that might otherwise sound over-modulated or
mildly distorted. Select the narrowband filter to improve
the selectivity of the receiver to provide greater resistance
to interference from older 40 channel wideband radios
operating on adjacent channels.
To select the desired filter
1. Press and hold MENU to enter the menu.
2. Press MENU repeatedly until ‘NBFLT’ (Narrowband Filter)
or ‘WBFLT’ (Wideband Filter) is displayed.
3. Press the or key to make the desired selection.
When finished briefly press the PTT to exit the menu.
Narrowband filter selected
Wideband filter selected
NOTE: The wideband receiver filter setting is only applied
to channels 1 – 40. Channels 41 – 80 always use the
narrowband filter.
DYNAMIC VOLUME CONTROL (DVC)
The modulation level of signals heard on the UHF CB band
has always varied considerably resulting in noticeable
differences in received audio volume between stations.
Generally users have compensated for this by adjusting
the Volume control for each incoming signal. With the
introduction of 80 channel narrowband transmissions that
use lower levels of modulation, the diversity in received audio
volume is likely to increase further.
Your radio is able to automatically compensate for these
variations in received audio level by utilising a Dynamic
Volume Control. When activated, this feature automatically
compensates for variations in received audio level resulting in
a constant audio output level to the speaker.
To activate the Dynamic Volume Control
1. Press and hold MENU to enter the menu.
2. Press MENU repeatedly until ‘DVCOF’ (Dynamic Volume
Control Off) or ‘DVCON’ (Dynamic Volume Control On) is
displayed.
3. Press the or key to make the desired selection.
When finished briefly press the PTT to exit the menu.
Dynamic Volume Control ON
Dynamic Volume Control OFF

PAGE 12 I NSTRUCTION MANUAL TX3550S
VOICE SCRAMBLER
Your radio incorporates a simple voice scrambler using band
inversion. The scrambler is compatible with the majority
of scramblers used by other manufacturers, allowing you
to enjoy scrambled communications with owners of non-
GME radios. Once the scrambler has been activated your
transmission and reception will only be intelligible to others
using the same scrambler technology.
To enable or disable the voice scrambler
1. Press and hold MENU to enter the menu.
2. Press MENU repeatedly until ‘ENCOF’ (Encoder Off) or
‘ENCON’ (Encoder On) is displayed.
3. Press the or to make the desired selection. Select
‘ENCON’ to activate the scrambler or ‘ENCOF’
to disable it.
When finished briefly press the PTT to exit the menu.
Scrambler Encoder OFF Scrambler Encoder ON
BEEP TONE VOLUME
The Key Beeps provide audible feedback whenever the keys
are pressed. You can adjust the volume of the key beeps
as follows.
1. Press and hold MENU to enter the menu.
2. Press MENU repeatedly until ‘BEEPx’ is displayed (where
x is a value from 0 – 9).
3. Press the or key to adjust the Beep volume
from 0 – 9.
• BEEP1 = minimum
• BEEP9 = maximum
• BEEP0 = Off
When finished, briefly press the PTT to exit.
DISABLING THE INTERNAL SPEAKER
The TX3550S has two speakers – one mounted inside the
radio and the other mounted inside the microphone.
By default, sound is reproduced by both speakers; however
if you prefer, the radio’s internal speaker can be switched off
leaving just the peaker/microphone to reproduce sound.
To switch off the radio’s internal speaker
1. Press and hold the MENU key.
2. Press MENU repeatedly until ‘SPKxx’ is displayed
(where xx = ON or OF).
3. Press or to make the desired selection.
4. Select ‘SPKON’ to switch the internal speaker ON.
5. Select ‘SPKOF’ to switch the internal speaker OFF
When finished press the PTT to exit.
MICROPHONE GAIN
The microphone gain adjusts the sensitivity of the
microphone’s to your voice input level. If you are quietly
spoken or are operating in a quiet environment you can
increase the microphone sensitivity to make your voice
sound clearer. If your voice is quite loud or you are working
in a noisy environment and wish to minimise the amount of
background noise that is picked up, you should reduce the
microphone sensitivity.
To adjust the microphone sensitivity
1. Press and hold the MENU key.
2. Press MENU repeatedly until ‘MICxx’ is displayed
(where xx = 0 to +9).
3. Press or  to make the desired selection. Press to
increase the microphone sensitivity or press  to decrease
the microphone sensitivity.
When finished press the PTT to exit.

TX3550S INSTRUCTION MANUAL PAGE 13
SILENT SQUELCH TAIL
The Squelch Tail is the short burst of noise that is heard in
the speaker at the end of a transmission just before the
Squelch closes.
To some it is a reassuring confirmation that it is their turn to
transmit but in some applications it may be an annoyance
especially when listening through an earpiece or headphones.
The Silent Squelch Tail function removes this Squelch Tail,
reducing it to a faint click as the Squelch closes.
To enable or disable the Silent Squelch Tail
1. Press and hold MENU to enter the menu.
2. Press MENU repeatedly until ‘SSTxx’ is displayed where xx
= ON or OF.
3. Press to enable the Silent Squelch Tail. ‘SSTON’ will be
displayed and the Squelch Tail will become silent.
4. Press to disable the Silent Squelch Tail. ‘SSTOF’ will be
displayed and the Squelch Tail will be restored.
When finished, briefly press the PTT to exit.
REPEATERS AND DUPLEX MODE
Duplex operation allows the radio to transmit on a different
frequency to that which it receives. This allows operation
through repeater stations.
A repeater station consists of a linked transmitter/receiver
combination installed in a prominent location. The repeater
is designed to receive signals on a designated channel and
retransmit them on another channel. Repeaters are usually
mounted on hills or tall buildings. The increase elevation
greatly improves both the receiving and transmitting range of
the repeater allowing it to receive and retransmit signals to
radios that would otherwise be out of range of each other.
Normally, UHF radios transmit and receive on the same
frequency – known as Simplex operation. However to
communicate through repeaters, your radio must be able to
transmit and receive on different channels – otherwise known
as Duplex operation. Your radio is fitted with a Duplex key to
allow you to operate through repeaters.
The Duplex function can only be selected on channels 1 – 8
and 41 – 48 as these are the channels that have been
allocated for repeater use. When Duplex is selected, your
radio receives on the selected channel (e.g. CH 1) but
transmits 30 channels higher (CH 31). The repeater hears your
signal on CH 31 and retransmits it on CH 1 for others to hear.
CHANNEL 31
CHANNEL 1
CHANNEL 1
CHANNEL 31
VEHICLE
SIMPLEX
REPEATER
OPERATION
VEHICLE
REPEATER
STATION
Your radio allows you to enable or disable Duplex mode
on individual repeater channels. In this way any repeater
channels that are not being used with repeaters in your area
can be used in Simplex mode for normal direct radio-to-radio
communications.

PAGE 14 I NSTRUCTION MANUAL TX3550S
Channel
Selected
Receive
Channel
Transmit
Channel
1 1 31
2 2 32
3 3 33
4 4 34
5* 5* 35*
6 6 36
7 7 37
8 8 38
41 41 71
42 42 72
43 43 73
44 44 74
45 45 75
46 46 76
47 47 77
48 48 78
*Emergency channel only
To Enable Duplex on a Repeater Channel
1. Select the required repeater channel (1 – 8, 41 – 48).
2. Press Ffollowed by the DUP key. The duplex symbol
will appear on the display accompanied by a high beep.
To Remove Duplex from a Repeater Channel
1. Select the required repeater channel (1 – 8, 41 – 48).
If duplex is currently selected, the duplex symbol will
be displayed.
2. Press Ffollowed by the DUP key. The duplex symbol
will disappear from the display accompanied by a low beep.
IMPORTANT: Channels 1 – 8, 31 – 38, 41 – 48 and
71 – 78 should only be used in Simplex mode if there are
no repeaters in or near your location that operate on the
selected channel. In particular, avoid operating in Simplex
mode on any of the repeater input channels 31 – 38 and
71 – 78 unless you are absolutely sure that there are
no repeaters in range using that channel. Inadvertently
transmitting on an active repeater input frequency in simplex
mode could cause interference to other users on that repeater
that would not be audible to your radio.
PRIORITY CHANNEL
The Priority channel feature allows you to instantly recall any
one of the 80 channels in your radio. This feature can be used
to provide instant access to your working channel or your
local repeater channel at the press of key. It is also used in
conjunction with the Group Scan mode.
To Store a Priority Channel
1. Select the required channel.
2. Press Fthen press and hold the LEVEL key. The channel
number will flash then a high beep will be heard as the
channel is stored.
To Recall a Priority Channel
1. Press Fthen briefly press the LEVEL key. The radio will
immediately switch to the Priority channel and ‘PRI’ will be
displayed for a few seconds.
NOTE: If the radio was scanning when the Priority channel
was recalled, the scan will be cancelled.
SCANNING
Your radio incorporates a scan function allowing selected
groups of channels to be scanned for signals. Channels
can be scanned at a rate of 40 channels per second.
When a signal is found, scanning will pause to allow
the signal to be heard then resume scanning when the
channel is clear again.

TX3550S INSTRUCTION MANUAL PAGE 15
SCAN GROUPS
Your radio supports three scan groups - Open Scan, Group
Scan and Network Scan. Each scan group has a separate
channel memory allowing you to program your choice of
channels into each group for scanning.
To select Open Scan, Group Scan or Network Scan, press F
then OS/GS. ‘OPEN’, ‘GROUP’ or NETWK’ will be displayed
at each press.
NOTE: Network scan is disabled by default and will not
appear in the scan group list unless it has been enabled. See
Network Scan further below for details on how to enable
and use Network Scan.
Auto Skip
While scanning, if an active channel in your scan group
becomes a nuisance by constantly interrupting the scan,
briefly press or while the radio is paused on that
channel. The busy channel will be temporarily removed from
the scan group to allow time for the channel to become clear
again and scanning will continue from the next channel in
the sequence. After 30 seconds the skipped channel will be
reinstated in the scan sequence.
If the unwanted active channel continues to interrupt the
scan even after the 30 second skip period has elapsed,
hold SCAN while the radio is paused on that channel. The
‘nuisance’ channel will be completely removed from the scan
group for the duration of that scan session. To restore the
channel, simply stop and restart the scan session using the
SCAN key (or switch the radio Off then On again).
NOTE: You can skip as many busy channels from the scan
group as you wish, however if you attempt to skip the last
remaining channel, all the previously skipped channels will be
restored to the scan group.
OPEN SCAN
Open Scan allows a group of channels to be scanned in an
ascending sequence. If a signal is found, the scan will pause
on that channel. During this time you can press the PTT on
the microphone and talk on the channel. Once the channel
has been clear for 5 seconds the scan will resume.
Example: Scanning Channels 1 – 8 in open scan
1 - 2 - 3 - 4 - 5 - 6 - 7 - 8
Selecting Open Scan
To select Open Scan, repeatedly press Ffollowed by OS/GS
until ‘OPEN’ is displayed.
Programming the Scan Memory
Your radio has all 80 channels factory-programmed into
the Open Scan memory. Any channels not required can be
removed.
To add or remove channels from the Open Scan memory:
1. Select the required channel using the or key.
2. Check to see if the scan symbol is displayed on that
channel.
• If is displayed, the selected channel is already in the
scan memory. To remove it, press and hold SCAN.
will disappear.
• If is not displayed, the selected channel is not in the
scan memory. To add it, press and hold SCAN. will
now be displayed on that channel.
Repeat to add or remove other channels in the scan memory.
Default Working Channel in Open Scan Mode
In the Open Scan mode, your default working channel is
the channel your radio switches to when you press the PTT
while scanning. To define your working channel simply select
the required channel before you press SCAN. e.g. to make
channel 24 your working channel, simply select channel 24
before pressing SCAN.

PAGE 16 I NSTRUCTION MANUAL TX3550S
To Begin Scanning
Briefly press SCAN. A high beep will be heard and the
symbol will animate. During this time the channel numbers
will scroll rapidly as the channels are scanned.
NOTE: If there are less than 2 channels programmed into the
scan memory when you press SCAN, a low beep will sound
and the command will be ignored.
Operating in the Open Scan Mode
If a busy channel is found, scanning will pause to allow the
signal to be heard and will remain there for as long as the
channel remains busy. Once the channel has been clear for 5
seconds, scanning will resume automatically.
If you don’t wish to listen to a busy channel, briefly press 
or while the radio is paused on that channel. The busy
channel will be temporarily removed from the scan group
to allow time for the channel to become clear again and
scanning will continue. The skipped channel will be reinstated
in the scan sequence after 30 seconds (see Auto Skip).
If you press the PTT while the radio is scanning, the scan will
pause and the radio will transmit on the working channel.
After the channel has remained been clear for 5 seconds
scanning will resume.
If your radio pauses on a busy channel and you wish
to talk on that channel, simply press the PTT during a
break in the conversation. If the busy channel was not
your working channel, it now becomes your new working
channel, replacing your previous working channel. Once your
communication has finished and the channel has been clear
for 5 seconds, scanning will resume.
If you need to use your Priority channel (for an urgent call),
briefly press PRI. The scan will be cancelled and the radio will
jump straight to the Priority channel.
GROUP SCAN
Group Scan allows you to scan a number of channels for
activity while also monitoring your Priority channel. The
receiver will scan the other channels ONLY WHILE THERE
ARE NO SIGNALS ON THE PRIORITY CHANNEL. If a signal
appears on the Priority channel it will override any signals
being received on any of the other channels. In addition, if
you press the PTT at any time, the radio will transmit on the
Priority channel.
Example: Scanning channels 1 – 8 with
priority channel
20 in Group Scan
1 - 2 - 3 - 4 - 20 - 5 - 6 - 7 - 8 - 20
Selecting Group Scan
To select Group Scan, repeatedly press Ffollowed by OS/GS
until ‘GROUP’ is displayed.
Programming the Scan Memory
1. Select the required channel using the  or key.
2. Check to see if the scan symbol is displayed on that
channel.
• If is displayed, the selected channel is already in the
scan memory. To remove it, press and hold SCAN.
will disappear.
• If is not displayed, the selected channel is not in the
scan memory. To add it, press and hold SCAN. will
now be displayed on that channel.
Repeat to add or remove other channels in the scan memory.
Select your Priority Channel
Program your Priority channel as described earlier under
‘Priority Channel’
To Begin Scanning
Briefly press SCAN. A high beep will be heard and the
icon will animate. During this time the channel numbers will
change rapidly as the channels are scanned with the Priority
channel scanned every fourth channel.
If a signal appears on the Priority channel – at any time – the
radio will switch directly to the Priority channel and will stay
there for as long as the channel remains busy. During this
time you can transmit and receive on the Priority channel.

TX3550S INSTRUCTION MANUAL PAGE 17
Once the Priority channel has been clear for 5 seconds the
radio will resume scanning the other channels.
If a signal appears on any other channel, scanning will pause
on that channel and will remain there while the channel is
busy – as long as there are no signals on the Priority channel.
During this time, the receiver will continue to check the
Priority channel every 2 seconds resulting in a series of small
breaks in the reception of the busy channel. Once the signal
has gone and there has been no activity for 5 seconds, the
radio will resume scanning.
To transmit on the Priority channel at any time, simply press
the PTT. The radio will switch straight to the Priority channel.
When you have finished your conversation and there has
been no further activity for 5 seconds, the radio will resume
scanning the other channels.
If you don’t wish to listen to a busy channel, briefly press
the or key while the radio is paused on that channel.
The busy channel will be temporarily removed from the scan
group to allow time for the channel to become clear again
and scanning will continue. The skipped channel will be
reinstated in the scan sequence after 30 seconds (see Auto
Skip).
If you need to use your Priority channel (for an urgent call),
briefly press the PRI key. The scan will be cancelled and the
radio will jump straight to the Priority channel.
If the radio is paused on a busy channel and you want to
remain there, briefly press SCAN. The radio will exit scan and
remain on the busy channel. At this point you will no longer
be monitoring the Priority channel.
To resume Group scanning press SCAN again.
NETWORK SCAN (NET-SCAN)
Net-Scan allows a group of radio users to maintain
communications even when the band is congested. To
achieve this all members of the Net-Scan group must share
a common CTCSS/DCS code and a common set of scan
channels.
Once activated, Net-Scan’s intelligent scanning software
keeps track of clear channels within your scan group. When
any member of the group transmits, their radio automatically
selects a clear channel to transmit on. Other radios scanning
in the same Net-scan group will lock onto that channel
allowing all members of the group to join the conversation.
If a signal from outside your Net-Scan group appears on the
chosen channel (either with no code or the wrong code), the
group will automatically switch to a new clear channel at
the next transmission. In this way the group can continue to
communicate with minimal interference to or from other users.
Enabling Net-Scan
Net-Scan is normally switched off by default but can be
enabled through your radio’s menu.
NOTE: When you enable Net-Scan you will also be prompted
to choose a suitable CTCSS or DCS tone to be used by your
Net-Scan group. All members of your Net-Scan group must
use this same code.
To Enable Net-Scan
1. Press and hold MENU to enter the menu.
2. Press MENU repeatedly until ‘NS xxx is displayed.
3. Press or to change the current Net-Scan setting.
• To enable Net-Scan using CTCSS, select from NS-01 to
NS-50 (CTCSS tones 01 to 50).
• To enable Net-Scan using DCS, select from NS001 to
NS104 (DCS codes 001 to 104).
• To disable Net-Scan, select ‘NS-OF’.
When finished briefly press the PTT to exit the menu.
Selecting Net-Scan
When Net-Scan is enabled, a Network scan option becomes
available in the scan group selection. To select Network
Scan, repeatedly press Ffollowed by OS/GS until ‘NETWK’
is displayed.

PAGE 18 I NSTRUCTION MANUAL TX3550S
Programming Channels into Net-Scan
All radios in your Net-Scan group must have the same
channels programmed into their Net-Scan memory.
Your radio’s Net-Scan memory has already been factory
programmed with 43 of the available 80 channels. The
remaining 37 channels, which consist of the 32 repeater
input/output channels, 2 telemetry channels and 3 guard-
band channels, have not been included to minimise the risk
of interference to other services on these channels.
To Add or Remove Net-Scan Channels
With Net-Scan mode enabled,
1. Select the required channel using the or key.
2. Check to see if the scan symbol is displayed on that
channel.
• If is displayed, the selected channel is already in the
scan memory. To remove it, press and hold SCAN.
will disappear.
• If is not displayed, the selected channel is not in the
scan memory. To add it, press and hold SCAN. will
now be displayed on that channel.
Repeat to add or remove further Net-Scan channels.
IMPORTANT: When adding channels to Net-Scan, please
consider the following:
• The transmitter on your radio is inhibited on channels 22,
23 and channels 61, 62, 63 as required by the ACMA.
This makes these channels unsuitable for use as Net-Scan
channels.
• You should not include any repeater channel unless you
have confirmed that the channel is not allocated to a
repeater in your area. Using an active repeater channel in
Net-Scan may result in interference to other repeater users
on that channel.
Starting Net-Scan
With Net-Scan mode enabled, press SCAN. A high beep will
be heard and the icon will animate. During this time the
channel numbers will change rapidly as the channels
are scanned.
Using Net-Scan
When a member of the group initiates a transmission their
radio will automatically select a clear channel to transmit on.
Other radios scanning in the same Net-Scan group will locate
the transmission by identifying the groups CTCSS/DCS code
and open their Squelch allowing the transmission to be heard
across the entire group. When the transmission ends, all
radios in the group will immediately resume scanning.
If a member of the group responds to the initial transmission,
they will automatically re-use the same channel as long
as the channel remains free of other signals. This allows
the radios in the group to respond more quickly to further
transmissions from others in the group.
If at any time, a signal from outside your Net-Scan group
appears on the channel (either with no code or the wrong
code), the channel will be discarded and a new clear channel
will be selected at the next transmission. The other radios
in the group will then locate the new channel allowing the
conversation to continue seamlessly without any input from
the user.
Ending the Scan
To stop scanning, briefly press SCAN. A low beep will be
heard and the animated icon will stop. As long as the
radio was not on a busy channel, it will return to the last
channel you selected, otherwise it will stay on the
busy channel.
Quick select/check
To quickly switch between channels that have been stored in
the current scan memory, briefly press the Fkey then press
or . This will allow you to manually step through only those
channels that have been stored in the current scan group
memory. During this time Fwill remain on the display to
confirm you are still in ‘Quick Select’ mode. To exit this mode,
press the Fkey again or wait 10 seconds for the function to
time out.
This option can be used to quickly jump between channels of
interest or to quickly review which channels are in the scan
memory for editing purposes.

TX3550S INSTRUCTION MANUAL PAGE 19
CTCSS AND DCS
The standard Squelch system is fine for quieting the radio
in most applications. However, it operates solely on signal
strength which means that it will always open to any signal
that is strong enough. If the channel is busy with other
stations the Squelch will be constantly opening making it
difficult to determine which calls are meant for you.
CTCSS (Continuous Tone Coded Squelch System) and DCS
(Digital Coded Squelch) are similar Squelch quieting systems
that provide selective audio muting using sub-audible
signalling. When enabled, only signals with a matching
sub-tone will be heard in the speaker. This effectively creates
a channel that is silent to all traffic except those you wish
to hear.
Choosing CTCSS or DCS
The CTCSS system uses 1 of 50 low frequency tones to open
and close the Squelch on the radio. The DCS system is similar
to CTCSS but uses 1 of 104 digital codes to control the
Squelch. There is no difference in performance or function
between the different tone sets so choosing which tone
system to use will largely depend on the other radios you talk
with. If others already use CTCSS or DCS, you should select
the tone system that matches theirs. If the users you talk to
don’t currently use CTCSS or DCS then you can make your
own choice. Both types are included in the radio to maintain
compatibility with other radio systems.
CTCSS Tone Set Compatibility
The GME CTCSS tone set comprises a table of 50 tones made
up of the standard CCIR-38 Tone Set plus an additional 12
tones added to the end. If communicating with other brands
of radios that only use the CCIR-38 tone set, please select
from one of the first 38 tones to ensure compatibility with
these radios.
If communicating with other GME radios, you may choose
from any of the 50 tones. However, please refer to the
tone set tables listed in each radio’s Instruction manual
for compatibility because, although the same 50 tones are
available in all GME radios, the tones used in older GME
models may be listed in a different order to those in
your radio.
To select a CTCSS or DCS code
1. Press MENU to enter the menu. ‘CTCxx’ or ‘DTxxx’ will be
displayed.
2. Press the or to enable CTCSS/DCS and select a
suitable CTCSS or DCS code.
• To select a CTCSS tone, select from ‘CTC01’ to ‘CTC50’
(CTCSS tones 01 to 50).
• To select a DCS code, scroll past CTC50 to select from
‘DT001’ to ‘DT104’ (DCS codes 001 to 104).
• To switch CTCSS/DCS off, select ‘CTCOF’.
Press
CTCSS Off CTCSS Tone 50 DCS Tone 104
Press
3. To see the actual sub tone instead of the tone table,
briefly press LEVEL key. For CTCSS tones the tone
frequency will be displayed in Hz. For DCS codes the code
will be displayed. Press the LEVEL key again to return to
the CTCSS/DCS label (refer to the CTCSS and DCS tone
charts later in this manual).
CTCSS
Label
CTCSS Sub Tone
Frequencey
When finished briefly press the PTT to exit the menu.
NOTE: The tone you select will be used for all channels that
have ‘Silent’ enabled.

PAGE 20 I NSTRUCTION MANUAL TX3550S
Enabling CTCSS/DCS on a Channel (Silent mode)
Enabling CTCSS/DCS on a channel will prevent the Squelch
from opening on that channel unless the incoming signal
matches your selected CTCSS/DCS tone. Other users on the
same channel who are not using your CTCSS/DCS tone will
still be received by your radio (the icon will still appear on
the display) – but their voice will not be heard in the speaker.
Only when someone transmits on the channel using your
CTCSS/DCS tone will the Squelch open to allow the signal to
be heard. Channels where CTCSS/DCS have been enabled are
said to be in ‘Silent mode’.
NOTE: Silent mode can be enabled on any channel except
emergency channels 5 and 35.
To Enable Silent Mode on a Channel:
1. Select the required channel.
2. Press and hold the SQL key until a high beep is heard.
3. An icon (CTCSS) or icon (DCS) will be displayed in
the lower right of the display to indicate Silent mode is
now enabled on that channel.
NOTE: You cannot enable Silent mode unless a CTCSS or
DCS tone has been selected in the Configuration menu. If
CTCSS/DCS has been set to OFF, Silent mode is inhibited.
To Disable Silent Mode on a Channel:
1. Select the required channel. An icon (CTCSS) or
icon (DCS) will be displayed indicating Silent mode is
enabled.
2. Press and hold the SQL key until a low beep is heard.
3. The (CTCSS) or (DCS) icon will disappear to indicate
Silent mode has been removed from that channel.
IMPORTANT: When Silent mode is enabled on a channel
you should always check the icon for signs of traffic on the
channel before transmitting to ensure you do not accidentally
transmit over the top of another user. Alternatively, you can
enable Busy Lockout in the Configuration Menu which
will automatically prevent your radio from transmitting if the
channel is already in use
Busy Lockout
When using Silent mode with CTCSS/DCS, your radio’s
receiver remains quiet to all signals outside your CTCSS/
DCS group. As a result, if you do not notice when others are
transmitting on your channel you could accidentally transmit
over the top of them.
The Busy Lockout function detects when others outside
your CTCSS/DCS group are transmitting on the channel
and prevents your radio from transmitting over them. If the
channel is busy and you press the PTT the radio will emit a
warning beep and the icon won’t be displayed. When
you release the PTT, look for the icon on the display as
an indicator that the channel is in use. If the channel is busy,
simply wait until the channel is clear and press the
PTT again.
NOTE: You can also press the Monitor key to open
the Squelch and listen for signals on the channel before
transmitting (see Monitor Function directly below).
To enable Busy Lockout
1. Press and hold MENU to enter the menu.
2. Press MENU repeatedly until ‘BLKxx’ is displayed (where
xx is ‘ON’ or ‘OF’.
3. Press  to enable Busy Lockout. ‘BLKON’ will be
displayed.
4. Press  to disable Busy Lockout. ‘BLKOF’ will be
displayed.
When finished, briefly press the PTT to exit.
Monitor Function
When the current channel is in Silent mode, the icon
may appear but no sound will be heard in the speaker. This
indicates that your radio is receiving a signal that does not
match your CTCSS/DCS tone. If you wish, you can briefly
monitor the channel as described below. This temporarily
disables Silent mode, allowing the signal to be heard.