CONTENT 1. GENERAL 1.1 General 1.2 Characteristic 1.3 Composition 2. SPECIFICATION 2.1 General Specification 2.2 Electrical Specification 3. OPERATION 3.1 Key Name 32 ICON on LCD 3.3 Key Functions 3.4 Setting and Operation 4. ADJUSTMENT 4.1 Frequency synthesizer 4.2 Transmitter 4.3 Transmitter Test 4.4 Receiver 4.5 Receiver Test 4.6 Symptoms, check point & Correction 5. DESCRIPTION OF RADIO CIRCUIT 5.1 Frequency Synthesizer 5.2 Receiver 5.3 Transmitter 6. BLOCK DIAGRAM 7. SCHEMATIC 8. COMPONENT PART LIST 9.
I. GENERAL 1.1 GENERAL This equipment, GARS-1525 is called 2 way portable handheld radio. The frequency range is 462.5625 ~ 462.7250MHz, UHF operating Channels for international 2 way radio. 1.2 CHARACTERISTIC a) All active device in this radio is composed of semiconductor and high density IC. b) To design this radio in compact and weight approximately 140g with out battery. ©) CPU of this equipment is M38223M4-HP from MITSUBISHI d) It’s power can operate by use of alkaline 4 AAA) battery. 1.
3.2 ICONS on LCD 1) Key lock indicator : Indicates that the key lock function is in use. 2) Receive signal indicator : Appears when receiving signal or squelch noise is existing. 3) Monitor indicator : Appears when the CSS isn’t in use and squelch is open. 4) Emergency channel indicator : Indicates while receiving a emergency channel. 5) Scan indicator : Indicates that scan is enabled. 6) CSS indicator : Appears when the CSS function is in use.
3.3 Key Function 1) Volume controls : Turn the power on and adjusts the audio level. 2) PTT switch : Push and hold to transmit ; release to receive. 3) Monitor / Lamp Key : Press and hold this key for over 2 seconds to enable the receive CSS feature. And Push this button momentarily to switch on for off the LCD back-lighting.
2) Function display a Tell EE EMG om A vai BABE 1) Key lock indicator : Indicates that the key lock function is in 2) Receive signal indicator © Appears when receiving signal 3) Monitor indicator : Appears when any CSS isn’ tin use and squelch 4) Emergency Channel indicator : Appears when emergency 5) Scan indicator : Indicates that scan is enabled.
BR 14) Channel readout : Shows the current channel number . 3-4, SETTING AND OPERATION 1) Basic Channel Selection In order to communicate with other GARS units, both you and the receiving party must be on the same channel. GMRS1525 has channels indicated by the large digits on 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.
NOTE : To communicate with other PMR units, they must be switched to the same channel and CSS sub-code. To communicate with other GARS units that do not have sub-codes, switch your unit to the same channel with the sub code set to OFF. 3) Auto Channel Scan List Selection Mode This feature allows you to scan for an active channel and communicate with the party transmitting. To access the Auto Channel Scan Skip List menu, -. Press the Mode Button until the Icon (SKIP) blinks on the LCD panel. -.
-. To turn off the Priority Scan feature while scanning mode, simply press the Scan button once. 5) 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 (refer to enclosed Accessory Order Form). Tt also allows hands-free use when a is not being used without having to the PTT button. To access the VOX Selection menu, -.
8) Call Ringer Selection Mode This feature provides 5 user delectable call ringer signal to alert you of a calling party. To select your favorite call ringer signal. -. Press Emergency button + Power ON. Appears the (C 01) icon blanks on the LCD panel. -. Press the Up button or Down button to preview the 5 available signal. ~. Press the PTT button to confirm your selection. -. To quickly activate the Call, Simply press PTT button 2 time click.
b) Check the voltage between TP & GND in digital volt meter. ©) Then set the low channel of TR-300 the lowest frequency. d) After pressed PTT key of TR-300, check if the lowest frequency of Tx channel to DC 1.5V in the voltage of test pointillist. &) After releasing the PTT key of TR-300, check if the highest frequency of Rx channel is within DC 1.0V in the voltage of test pointillist. 4-2. Transmitter a) Connect EUT & measure equipment according to block diagram below.
d) Adjust Tx frequency according to trimming trimmer VvC201. ¢) Connect AF Oscillator to mic terminal for conform modulation degree. f) Adjust the frequency of AF Oscillator to 1 kHz and adjust AF level Should be 100mV. 8) Checking Oscilloscope and Modulation Meter. Max deviation should be in 42.5 kHz. 4-3. Transmitter Test 2) Output Power Test Power(DC 6.0V) should be Max. 2 TWERP) and in -50% range.
4-4, Receiver 2) Preparation 1) Adjust the power supply to DC 6.0V. 2) Adjust Voltage level to load) after power on. b) Connection method 88G EUT 89 Load Power Supply Oscilloscope AV MTV Distortion M SIN AD Meter ¢} The Conform of Rx sensitivity 1) Adjust SSG to channel frequency. 2) Adjust modulation frequency , kHz to modulation 3) After adjusting the frequency of SSG to channel frequency, RF novel sets to ~47dBm. d) The Conform of Squelch sensitivity 1) Set the standard channel.
4-5. Receiver Test #) Rx sensitivity test SSG should be adjusted SIN AD point needle seeing wave of Oscilloscope as SSG sets in kHz frequency deviation. At this time , normal RF level is ~110 ~ -107dBm. b) Audio Distortion Test 1) $8G should be adjusted like way of point “a)” and RF level sets to -47 dBm. 2) Adjust to load) seeing Audio wave.
.. Audio does not sound (Tx power and Tx frequency are normal) @ Problem of microphone or mic connector. ® ASP(Audio Signal Processor) IC U102 problem. -. Tx is set when switch switcher) problem. 2) Receiver -. Rx does not work Speaker line open problem or connector problem. (® Receiver power circuit problem. ® Audio amplifier Base band IC U103 problem. -. Only noise sound IF IC U301 problem. ® VCO circuit problem. -. Rx sensitivity is weak @ Antenna mounting problem. (® Receiver front-end circuit problem.
$. DESCRIPTION OF RADIO CIRCUIT 5-1. Frequency synthesizer Frequency synthesizer consists of VCO,PLL Builtin in SCALPER) and’ Loop filter. 2) VCO VCO is composed of One VCO, Oscillation circuit takes cockpits circuit using variable Diode. And VCO is composed of D401, L402, C401, C402, C403 D402, Q401, Q402. VCO control voltage through loop filter adjusts frequency and Microphone Sigma! through Modulation terminal makes modulation.
Conversion Circuit Rx signal goes conversion circuit through FIXED antenna connector, low pass filter and receiver resonance circuit composed of When transmitting, Voltage through supplies, D202 of receive input is short and Tx is on condition. When PIN diode is off in condition of Rx, C301,C302 L301 resonate serially and make impedance matching at receiver band pass filter. (FL301,FL302} b) Front End Front-end has Q301 to provide a high sensitivity and low noise feature.
After 2nd TF AMP has a process of enough gain and AM rejection, it comes to quadrature detection. Demodulated audio signal by X301 is amplified and comes out 10 pond. Detected audio signal through R313, VR] and input in audio amp. Audio IC U105 through R149. © Squelch Circuit Noise component of detected outputs has amplification squelch threshold 1s controlled by Resistor R310,R312,VR301. f) Audio Amplifier Demodulated audio signal enters to pin of AF IC (U105).
