- Computers & electronics
- Telecom & navigation
- Two-way radios
- Columbia Telecommunications Group
- MURS
- User manual
- 14 Pages
Columbia Telecommunications Group MURS two-way radios Instruction manual
Columbia Telecommunications Group GAFMURS2 is a MURS unit operating in the frequency range of 151.820 ยก -154.600MHz and allows for communication between multiple units over short distances. It offers 5 main channels and 38 sub-channels for each main channel, providing a total of 190 channels. The device is equipped with a built-in microphone and speaker, as well as an external microphone/speaker jack for hands-free operation. Other features include a backlit LCD display, adjustable volume, and a belt clip for easy carrying.
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6. Instruction Manual
1) Safety Information
Safety Information For MURS UNIT
Your wireless handheld portable transceiver contains a low power(2watts)
Transmitter.
When the Push-to Talk (PTT) button is pushed it sends out radio frequency (RF) signals.
This device is authorized to operate at a duty factor not to exceed 50%.
In August 1996, the Federal Communications Commission (FCC) adopted RF exposure guidelines with safety levels for hand-held wireless devices.
Important Note:
To maintain compliance with the FCC's RF exposure guidelines, hold the transmitter and antenna at least 1 inch (2.5 centimeters) from your face and speak in a normal voice, with the antenna pointed up and away from the face.
If you wear the handset on your body while using the headset accessory, use only the manufacturers supplied belt clip for this product and ensure that the antenna is at least 1 inch (2.5 centimeters) from your body when transmitting.
Use only the supplied antenna. Unauthorized antennas, modifications, or attachments could damage the transmitter and may violate FCC regulations.
THIS DEVICE COMPLIES WITH PART 15 OF THE FCC RULES. OPERATION IS
SUBJECT TO THE FOLLOWING TWO CONDITIONS:
(1) THIS DEVICE MAY NOT CAUSE HARMFUL INTERFERENCE, AND
(2) THIS DEVICE MUST ACCEPT ANY INTERFERENCE RECEIVED, INCLUDING
INTERFERENCE THAT MAY CAUSE UNDESIRED OPERATION.
2) General
a) General
This equipment, MURS is called 2 way portable handheld radios.
International 2 way portable radios. b) Characteristic
a. All active devices in this radio is composed of semiconductor and high density
IC.
b. To design this radio in compact and weight approximately 140g including
Battery.
c. CPU of this equipment is HD4074899TE from HITACHI.
d. It’s power can operate by use of alkaline 4 cell (1.5V AA) battery.
c) Composition
This radio is composed of following.
a. Transmitter (W/Antenna)
b. Belt clip
c. Ni-MH battery (option)
3) Specification
a) General Specification
Weather Range: 161.650 ~ 163.275 (Receiver Only)
c. Modulation Type: 8K0F3E
d. Communication Mode: Half duplex
e. Channel Capacity: 5 channels(MURS), 10 channels(WX)
f. Channel spacing: 12.5 KHz
g. Power: 6.0V(alkaline)
h. Battery Life: ALCA.2600mAh >40 hours (Tx5%, Rx5%, Stand-by 90%)
j. Dimension: 95.5(H) x 50(W) x 26(D) mm
k. Weight: 140g(with Battery)
b) Electrical Specification
a. Transmitter
1. Output power: Max. 2.0W
3. Modulation Method: FM
4. Oscillation Method: PLL SYNTHESIZER
5. Max. Frequency Deviation : < ¡ ¾
6. Cooling Method: air-cooling Method
7. Spurious Emission: < 60dB
8. FM Hum/Noise: > -40dB(1kHz 60% modulation, w/CCITT)
9. Distortion: < 5% (1kHz 60% modulation)
3dB PRE-EMPHASIS (300Hz¡ -
b. Receiver
1. Receive Method: Double Super Heterodyne
2. Receive Sensitivity: < 0.28uV(20dB SINAD w/CCITT)
3. Squelch Sensitivity: 6¡ -
4. Bandwidth: > 3kHz(6dB ATT point)
5. Selectivity: < -60dB(12.5kHz)
7. Spurious Response: > 40dB
8. Audio output: 200mW(Internal 8¥ Ø
9. Distortion: < 5% (1kHz 60% Modulation)
3dB DE-EMPHASIS (300Hz¡ -
11. S/N Ratio: < 40dB(1kHz 60% modulation w/CCITT)
12. IF: 1'st IF = 21.7MHz
2'nd IF = 450kHz
13. Local Frequency: 1st Local Frequency = fc - 21.7MHz
2nd Local Frequency = 21.25MHz
4) Operation
a) Key Name a. Function and Controls
1. Antenna
2. Belt Clip
3. Detachable Belt Clip Button
4. Power Switch
5. Mode/Scan Button
6. Vox Button
7. Lock Button
8. Wx Button
9. Built-in Microphone
10. Battery Cover
11. Charge Terminal
12. External Mic/Speaker
13. LCD Display
14. Push-To-Talk (PTT)
15.Monitor Button
16. Call Button
17. Up Down Button
18. Built-in Speaker
b) Icons on LCD
a. RSSI (Receiving Signal Strength Indicator) Icon
Indicates the receiving signal strength
b. Monitor or Receiving Indicator
Appears busy icon when the monitor button is long (about 0.5 sec.) used.
Short press the Mon button and would be emitting the backlight lamp during
5 seconds. c. CTCSS Indicator
Tone digits blink before when the select CTCSS tone CH. d. Auto Channel Scan Indicator
SCAN icon appears in the auto scan mode or when the auto scan mode is
activated.
e. Key Lock Indicator
Blinks in auto lock selection mode or when the key lock is activated.
f. VOX Indicator
VOX icon blinks in VOX selection mode or appears when VOX is activated.
g. Battery Level Indicator
Battery Level Meter indicates the remaining battery strength.
h. Power Save Display
P/SAVE icon blinks when the power save is activated.
the rate at which the icon blinks varies with the power saving ratio.
j. Rx Indicator
Appears and RX icon when a signal is being received.
l. Hi/Lo indicator
When use Hi/Lo power wanted power state.
m. Large Segment Display
Indicates the channel number in use at the normal mode.
When the Function Button is pressed.
n. Small Segment Display
Displays the CTCSS tone option at the normal mode.
o. Roger beep Segment Display
ROGER icon appears when the Roger beep activates.
p. Tx Indicator
Appears and TX icon when a signal is being transmission r. Appears and WX icon when a signal is being received
(weather band)
c) Key Function
a. Power Volume
- When power is on, briefly to press the unit on.
A short confirming melody will play.
b. Mode button
- Press this button briefly to enter function edit mode in standby mode.
c. Up/Dn button
- In the function edit mode, press briefly to shift from the current option in each
sub-menu to the next option in the same sub menu.
d. Push-to-Talk (PTT) button
- Press it firmly and speak into the Built-in Microphone to transmit.
- Release it to revert to standby mode. When an incoming call is received,
- Call Ringer
Press the CALL Button to call another party on the same channel.
The word CALL will appear in the display.
e. Monitor button
- Press it to check activity on the current channel.
- When you press the Monitor Button, the LCD Panel will be illuminated
with a Green color backlight.
f. External Mic/Speaker
- This jack accepts an optional headset/microphone for totally hands-free operation.
d)
Setting and Operation
a. Basic Channel Selection
In order to communicate with other MURS units, both you and the receiving party must be on the same channel.
MURS has 5 channels (1-5) as indicated by the large digits in the LCD
Display Panel. Before, trying to transmit on the selected channel, you should press the Monitor Button to check the activity on that channel. If someone is already on the selected channel, you should try another channel that is clear.
To change the basic channel,
- In the menu mode, press the Up/Dn button briefly to move to the next
higher or lower main channel number. b. CTCSS (Coded Tone Controlled Squelch System) Sub-Channel Selection
MODE
This feature allows you to utilize a less used channel range (0-38) within a main channel. This enables you to communicate with another party on the same main channel using the same sub-code. This helps to avoid congestion on the main channel and filters out unwanted noise and static.
There are 38 CTCSS sub-channels for each main channel.
To change the CTCSS sub-channel,
- Press the Function Button until the blink tone digits in the LCD Panel.
- Press the Up/Dn Button to choose the desired sub-channel to use.
The corresponding sub-code CH will be displayed in the lower right corner.
- Press the any button to confirm your selection.
NOTE: To communicate with other MURS units, they must be switched to the same channel and CTCSS sub-code. To communicate with other MURS units that do not have sub-codes, switch your unit to the same channel with the
Sub-code set to OFF. e) AUTO Channel SCAN MODE
This feature allows you to scan for an active channel and communicate with the party transmitting.
To access the Auto Channel Scan menu,
- Press the scan Button until the auto channel icon blinks and SCAN icon appears in the LCD Panel.
- Press the Up or Down Button to choose scanning up or down from the current channel number.
- Press the PTT Button, want to return home CH.
- The unit will begin scanning for an active main channel. If a transmission is detected, the Rx and RSSI icons will appear in the LCD Panel.
- To turn off the auto channel scan feature in the standby mode, simply press the
CALL button and then CH will be return to home CH.
f) VOX Selection MODE
The Voice Activated Transmission (VOX) function allows your voice to activate transmission automatically when the Communicator is used with the optional hands-free mic/headset. It also allows hands-free use when a mic/headset is not being used without having to use the PTT Button.
To access the VOX Selection menu.
- Press the VOX Button until the VOX icon appears in the LCD Panel.
- Press the VOX Button to select from on or off.
g) Lock Selection MODE
This feature prevents accidental channel change and disturbance to the preferred settings of the Communicator. Lock temporarily disables the Up, Down
Vox,WX and Mode/Scan Buttons.
- Press the Lock Button until the lock icon appears in the LCD panel.
- Press the Lock Button to confirm the other menu moving with your selection.
5) Adjustment
a) Frequency synthesizer (PLL)
a. After connecting the power meter and dummy load (50), join the antenna
connector of MURS with above equipment.
b. Check the voltage between TP1 & GND in digital volt meter.
c. Then set the low channel of MURS the lowest frequency.
d. After pressed PTT key of MURS,trimmer CV71 for adjusting the lowest
frequency of Rx channel to DC 1.0V in the voltage of TP1.
e. After releasing the PTT key, and then check if the highest frequency of Rx
Channel is range DC 1.0~2.5V in the voltage of TP,
f. WX with above equipment
The lowest frequency of Rx channel to DC 1.2V in the voltage of TP1. b) Transmitter a. Connect EUT & measure equipment according to block diagram below.
POWER SUPPLY MODULATION METER
EUT
AF OSCILLATOR
POWER METER DUMMY LOAD
OSCILLOSCOPE
AV VTVM
DISTORTION METER
SPECTRUM ANALYZER
FREQUENCY COUNTER
b. Connect DC 6.0V, voltage preset to EUT.
d. Adjust Tx frequency according to trimming trimmer CV401.
e. Connect AF oscillator to mic terminal for conform modulation degree.
f. Adjust the frequency of AF oscillator to 1KHz and adjust AF level should be
100mV.
g. Checking oscilloscope and modulation meter. Max. Frequency deviation should be in ¡ ¾
c) Transmitter Test
a. Output Power Test
Power (6.0V DC) should be Max.2.0W and in +-10% range.
b. Audio Response
Connect AF oscillator to Mic terminal and then firm the audio level
that doesn't distortion the wave of oscilloscope in the frequency range,
3kHz. Check the audio level for 300Hz¡ -
standard, 1kHz.
c. Modulation Degree Test
1. Connect AF oscillator to the MIC terminal and then adjust the level to 100mV
2. Measure the oscilloscope wave and he point needle of modulation meter
after pressing PTT key.
3. Sweep gradually the frequency of AF oscilloscope from 300Hz to 3kHz.
4. At this time, the point needle of modulation meter should be in ¡ ¾
d. Spectrum Test
1. Antenna is 50¥ Ø
2. observe the spectrum with pressing PTT key. The harmonics should be
less 60 dB than carrier.
d) Receiver
a. Preparation
1. Adjust the power supply to DC 6.0V
2. Adjust Voltage level to 0.8Vrms(8¥ Ø
b. Connection method
SSG EUT
POWER SUPPLY
c. The Confirm of Rx sensitivity
OSCILLOSCOPE
AV VTVM
DISTORTION METER
SINAD METER
1. Adjust SSG to channel frequency.
2. Adjust modulation frequency, 1KHz to modulation degree, 1.5 KHz.
3. After adjusting the frequency of SSG to channel frequency, RF level
sets to -47dBm.
d. The Conform of Squelch sensitivity
1. Set the standard channel.
. 2. After adjusting SSG to channel frequency, the RF level of SSG is set
on SINAD 8¡ -
e) Receiver Test
a. Rx sensitivity test
SSG should be adjusted to 12dB of SINAD's point needle seeing wave of oscilloscope as SSG sets in 1kHz with 1.5 KHz frequency deviations. At this time, normal RF level is -118dBm.
b. Audio Distortion Test
1. SSG should be adjusted like way of point a) and RF level sets to -47dBm.
2. Adjust to 0.8Vrms(8¥ Ø
3. Read the needle of distortion meter (normal condition would be less
than 5% distortion.)
c. Squelch Test
After RF level of SSG should be set to the least level, RF level should be gradually increased until speaker makes audio sound. At this point, check RF level(Check if the SINAD is 8¡ -
f) Symptoms, Checkpoint & Correction
a. Diagnosis method
1. Check each switch to work well.
2. Check voltage of battery.
3. Problem develops from transmitter or receiver?
b. Troubleshooting
1. Transmitter
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2. Receiver
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6) Specification sheet
* Carrier power
* Frequency Tolerance
* Maximum deviation
* Audio distortion
* Hum & Noise
* TX current
* Adjacent channel power
* Spurious emission(TX on)
LIMIT
2.0W max.
+/- 1.2KHz
+/- 2.5KHz
5% max.
40dB min.
1000mA max.
60dBc
60dBc
UNIT
W
KHz
KHz
% dB mA dBc dB
* Useable sensitivity
* 20dB N/Q sensitivity
* Squelch sens. Threshold
Tight
* Modulation acceptence
* Maximum audio out-put power
* Hum & Noise
* Audio distortion
* Stand-by current w/o saving w/ saving (1:4)
* Co-channel rejection
* Adjacent channel selectivity
* Spurious response attenuation
* Intermodulation distortion
* RX blocking
* Spurious emission(1M - 1GHz)
(1G - 12GHz)
Operating Time calculations
* Battery type
* Battery Capacity
* TX Current
* Stand-by current
* RX Current
* Operating Times
* TX Talking Times
* TX Power
* Battery Voltage
* TX Efficiency
-119dBm min.
-115dBm min.
-128dBm min.
-118dBm max.
Non
7.5KHz min.
100mW min.
40dB min.
5% max.
40mA max.
20mA max.
-12dB
50dB min.
40dB min.
50dB min.
NA
-57dBm max.
-47dBm max.
5 : 5 : 90
AA * 4
2600
1000
40
120
36.2
3.3
2000
6
28
KHz mW dB
% mA mA dB dB dB dB dBm dBm
ALKA mAH mA mA mA
Hours
Hours mW
V
%
7) Channel Data
(
Unit: MHz)
Channel TX Frequency 1st Local
1
2
151.82
151.88
130.12
130.18
3
4
5
151.94
154.57
154.6
130.24
132.87
132.9
WX
1
2
5
6
3
4
162.55
162.4
162.415
162.425
162.45
162.5
140.85
140.7
140.715
140.725
140.75
140.8
7
8
9
162.525
161.65
161.775
140.825
139.95
140.075
10 163.275
141.575
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Key Features
- Low-power (2watts) transmitter
- Duty factor not to exceed 50%
- CTCSS sub-channel selection
- AUTO channel scan
- VOX selection
- Lock selection
- FCC compliance