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Choosing a Channel

Your radio has 22 channels and 38 CTCSS codes
you can use to talk to others. In order to speak to
someone, each of you must be set to the same
channel and CTCSS code.

To choose a channel:

With the radio in "Normal" operating mode press the

ch/scan

key and press the 

or 

key to increase or

decrease the channel number displayed.

Note:

Channels 1-7 have an expectancy range of

up to 6 miles. Channels 8-14 have an expectancy
range of up to 2 miles. Channels 15-22 have an
expectancy range of up to 6 miles.

Choosing a CTCSS Code

Each of the channels 1-22 may have any one of
the codes, OFF or 1-38 selected. Code 

oF

(OFF) 

indicates no CTCSS code selected and your radio
can receive a signal regardless of the code settings
of the transmitting radio.

1) Enter the Menu. The CTCSS code on the LCD

display will appear.

2) Press the 

or 

key to increase or decrease

the code number displayed. You can also select

oF

(OFF) at this stage.

3) Exit the Menu.

Talking on Your Radio

To talk to others using the radio:

1) Press and hold the 

PTT

button and speak in a

clear, normal voice about 2-3 inches away from
the microphone. While you are transmitting, the

icon will appear on the display. To avoid 

cutting off the first part of your transmission,
pause slightly after pressing the 

PTT

button

before you start talking.

2) When you are finished speaking, release the 

PTT

button. You can now receive incoming calls. While
receiving, the 

icon will appear on the display.

Voice Operated Transmission

Your GMR645-2CK radio is equipped with a user 
selectable Voice Operated Transmitter (VOX) that
can be used for automatic voice transmissions. The
VOX feature is designed to be used with a headset
with a microphone. Transmission is initiated by
speaking into the remote microphone instead of
pushing the 

PTT

button.

GMR645-2CK

*Range may vary depending on environmental and/or topographical conditions.

• 15 GMRS / 7 FRS Channels
• 38 CTCSS Codes
• Up to 6 Mile Range*
• Internal VOX Circuitry
• 5 Selectable Call Tone Alerts
• Backlit LCD Display
• Optional Headset Accessories
• Headset Jack
• Roger Beep

1

Antenna

2

PTT (Push-To-Talk) Button

3

Monitor Key

4

Call Key

5

WX/Alert Key

6

Channel/Scan Key

7

Speaker

8

Headset Jack

9

Up Key

10 On/Off/Select Key
11 Microphone
12 Down Key
13 Battery Level Meter

14 Receive Indicator
15 Call Indicator
16 Scan Indicator
17 Channel Indicator
18 Alert Indicator
19 Weather Indicator
20 Transmit Indicator
21 Volume Setting Indicator
22 VOX Indicator
23 GMRS/FRS Indicator
24 Keypad Lock Indicator
25 CTCSS Indicator
26 Charging LED’s

Congratulations on your purchase of the Uniden
GMR645-2CK (General Mobile Radio Service)
radio. This product is a lightweight, palm-sized
radio. Use it at sporting events to stay in contact
with family and friends, hiking, skiing, outdoors, or
in a neighborhood watch for vital communication.
This compact, state-of-the-art device is equipped
with many features.

PACKAGE CONTENTS

Your package contains two GMR645-2CK radios,
two rechargeable NiMH battery packs (#BP38), AC
adapter (#AC6248), Recharging cradle (#RC6348),
two belt clips and this reference guide. You may
operate the unit using the rechargeable NiMH 
battery pack or 4 AAA alkaline batteries 
(not included). The following optional accessories
may be purchased from your participating Uniden
dealer or call1-800-554-3988 or visit us on the web
at www.uniden.com.

Use only Uniden accessories.

•  NiMH Battery Pack - #BP38

•  Recharging Cradle - #RC6348

•  Headset - #HS2467

FCC GMRS LICENSE

The GMR645-2CK radio operates on the General
Mobile Radio Service (GMRS) frequencies which
require a Federal Communication Commission
license to operate. For licensing information and
application forms, visit the FCC online at:
www.fcc.gov/wtb/uls or call the FCC hotline at 
1-800-418-3676. If you have any questions, you
can contact the FCC direct at 1-888-225-5322.

INSTALL THE BATTERY

Your GMR645-2CK radio uses the NiMH battery
pack or 4 AAA alkaline batteries (not included).

To install the NiMH battery pack:

1) Make sure your radio is OFF.
2) Remove the battery compartment door by 

pressing the tab at the bottom of the 
compartment door allowing the door to be
removed.

3) Install the NiMH battery pack into the battery

compartment. Be certain to follow the instruction
written on the label on the battery pack.
Installing the battery pack incorrectly will prevent
the unit from operating.

4) Replace the battery compartment door.

USING THE RADIO

In order to get the most out of your new radio, read this
reference guide completely before attempting to operate
the unit.

Turning the Radio On and Adjusting the Volume

1) Press and hold the 

sel/

key to turn the radio ON,

and increase the speaker volume by pressing the 

key. To decrease the volume, press the 

key.

2) Press and hold the 

sel/

key again to turn the radio

OFF.

Adjusting the Sound (Key Beeps)

Your radio emits a beep each time one of the buttons or
keys (except for the 

PTT

button and 

call

key) are pressed.

To turn this sound OFF, press and hold the 

call

key while

turning ON the radio. Repeat this step to turn the sound ON.

Navigating through the Menu

To access the advanced features of the GMR645-2CK,
your radio has a Menu function.

• Battery Charger
• Battery Level Meter
• Channel Monitor
• Channel Scan
• Keypad Lock
• NOAA Emergency / 

Weather Channels

• Emergency Weather Alert

BATTERY LEVEL AND

LOW BATTERY ALERT

This unit has a battery level meter on the display to 
indicate the status of the batteries. When the battery in
the unit is low, the battery level meter icon 

will

flash. Recharge the NiMH battery pack immediately or if
you are using the alkaline batteries, you must replace the
alkaline batteries in order to continue using the radio.

Warning!

To avoid the risk of personal injury or property

damage from fire or electrical shock, only use the Uniden
accessories specifically designated for this product.

1) To enter the Menu, press the 

sel/

key.

2) Additional presses of the 

sel/

key will advance

you through the Menu until exiting to "Normal" 
operating mode.

3) Other methods of exiting the Menu function are:

a. Press and hold the 

sel/

key again.

b. Press the 

PTT

mon

call

wx/alert

, or 

ch/scan

key

c. Wait 10 seconds until the unit automatically returns to

“Normal” mode.

To select the VOX level:

1) Enter the Menu. Advance through the Menu until

the 

vox

icon appears on the display. The current

level (OFF, 1-3) will be indicated. Level

oF

(OFF)

disables VOX, while levels

-

set the 

sensitivity of the VOX circuit.

2) Press either the 

or 

key to the desired VOX

sensitivity level. Use level 1 for increased 
sensitivity to voice in normally quiet 
environments, and use a higher level to reduce
undesired activation in very noisy environments.

3) Exit the Menu.

Transmitting a Call Tone

Your GMR645-2CK radio is equipped with 5 
selectable call tones that will be transmitted when
the 

call

key is pressed.

To select a call tone:

1) Enter the Menu. Advance through the Menu until

the 

call

icon is shown on the display. The current

call tone number (

-

) will be indicated.

2) Press the 

or 

key to increase or decrease

the number to the desired call tone. Each tone
will be heard through the speaker.

3) Exit the Menu.

To transmit the selected call tone, press the 

call

key. The selected tone will automatically be 
transmitted for a fixed length of time. Call Tone will
be cancelled when the 

PTT

button is pressed.

Channel Scan Feature

Your GMR645-2CK radio has a channel Scan 
feature that allows you to easily Scan all 22 
channels. When an active channel is detected, the
radio will pause on that channel until the channel is
clear. Then after a 2 second delay, the radio will
continue scanning. Pressing the 

PTT

button while

the Scan is paused on a channel will allow you to
transmit on that channel.

To turn ON channel Scan:

Press and hold the 

ch/scan

key until the 

scan

icon

is displayed. The channel number on the display
will change as the radio rapidly cycles through the
channels. You can know which GMRS or FRS
channel is active by the icon. The 

icon indicates

scanning GMRS channel, and the 

icon indicates

scanning FRS channel.

To turn OFF channel Scan:

Press the 

sel/

,

call

PTT

, or 

wx/alert

key, or

press and hold the 

ch/scan

key for 2 seconds.

Key Lock

To Lock the keypad:

1) Enter the Menu. Advance through the Menu until

the 

icon appears on the display. The current

Key Lock status 

oF

(OFF) blinks on the display.

Normal

Normal

CTCSS

VOX Level

Call Tone

Key Lock

1-5

OFF, 1-38

OFF, 1-3

ON-OFF

GMR645-2CK RADIO

2) To switch the Key Lock mode from 

oF

(OFF) to

on

, press the 

key.

3) To confirm the setting, press the 

sel/

key.

The radio returns to the "Normal" mode.

Note:

If you exit the setting mode before confirming

your selection by pressing the 

sel/

key, the key

Lock setting will be set to

oF

(OFF)

.

To Unlock the keypad:

1) Press and hold the 

sel/

key to turn the radio

OFF.

2) Press and hold the 

sel/

key again to turn the

radio ON. The keypad is unlocked.

Automatic Power Save Feature

Your GMR645-2CK radio has a unique circuit
designed to dramatically extend the life of the 
batteries. If there is no transmission nor an 
incoming call within 3 seconds, your radio switches
to the Power Save mode. The radio is still able to
receive transmissions in this mode.

LCD Backlight

The LCD Backlight will automatically turn ON when
any key (except the 

PTT

button) is pressed. The

LCD display will illuminate for 10 seconds before
turning OFF.

Monitor Mode Feature

Your GMR645-2CK radio allows you to listen for weak
signals on the current channel at the press of a key.

To turn ON the Monitor Mode:

Press 

mon

for brief listening, the 

icon will

blink.

Press and hold 

mon

for 2 seconds for continuous

listening. The receiver circuit will stay open, and
letting in both the noise and weak signals.

To turn OFF Monitor Mode:

Press 

mon

to return to "Normal" mode, and the

icon stop blinking.

Roger Beep

Roger Beep is a BEEP that is sent to notify the end
of transmission (both PTT and VOX transmission).
Roger Beep can be heard through the speaker
when Key Beep is on. Roger Beep is transmitted
even if Key Beep is turned off. However Roger Beep
will not be heard from the speaker.

To turn ON Roger Beep:

Press and hold the 

key while turning ON the

radio.

To turn OFF Roger Beep:

Press and hold the 

key while turning ON the

radio.

USING THE CHARGING CRADLE

If you use the rechargeable NiMH battery pack, two
GMR645-2CK radios can be charged by using the
charging cradle.

Make sure to turn the radio OFF before placing
the radio in the charging cradle. Otherwise the
battery level meter icon won’t indicate properly.

1) Connect the AC adapter (# AC6248) to DC IN 9V

jack and to a standard 120V AC wall outlet.

2) Set the charging cradle on the desk or tabletop,

and place the radio in the charging cradle with
the keypad facing forward.

3) Make sure that the LED illuminates. Charge the

battery pack for 16 hours and remove the radio
from the charging cradle after charge.

Note:

The charge indicator LED's will remain on as

long as the radios are left in the charger.

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