SERVICE MANUAL TECtalk
Contents
1. 1kHz 60 Modulation 0 RX Audio Response 6dB OCT 3dB DE EMPHASIS 300Hz to 2 5kHz 1 1 11 S N Ratio lt 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 3 OPERATION 3 1 Push Buttons and Controls oo _l _J iD o mM 1 Battery Door 2 Monitor Button 3 Detachable Belt Clip 4 Push To Talk PTT Button 5 Antenna 6 External Mic Speaker 7 Built in Speaker 8 LCD Panel 9 Built in Microphone 10 11 4 1 Up Button amp Volume Control Down Button amp Volume Control 2 Function Button 3 Power On Off amp Enter Button 3 2 ICONS on LCD WV iul Pat Payer EX Li Lou A r Ko T Su y m J t Lt m c ang EY RE A Appears when the monitor button is used 3 CTCSS Indicator e Blinks when the correct CTCSS tone is entered 4 Auto Channel Scan Indicator Appears in the auto scan mode or when the auto scan mode is activated 5 Dual Watch Scan Indicator Appears in dual watch scan mode or when the dual watch scan mode is activated VII 6 Key Lock Indicator Blinks in auto lock selection mode or when the key lock is activated 7 VOX Indicator s E Blinks in VOX selection mode or appears when VOX is activated 8 Battery Level Indicator mm Battery Level Meter indicates the remaining battery stren2. 2 RECEIVER Rx does not work Speaker line open problem or connector problem Receiver power circuit problem Audio amplifier Base band IC U4 problem Only noise sound U12 problem VCO problem Rx sensitivity is weak Antenna mounting problem Front End circuit problem SF1 SAW filter fail VCO problem Squelch does not work U12 problem Control logic problem L Local oscillation frequency deviation 5 DESCRIPTION OF RADIO CIRCUIT 5 1 Frequency synthesizer Frequency synthesizer consists of VCO PLL IC built in PRESCALER and loop filter a VCO VCO is composed of ONE VCO Oscillation circuit takes colpitts circuit using variable Diode And VCO is composed of D1 Q8 Q9 C81 C75 VC1 L1 C74 C76 VCO control voltage through loop filter adjusts frequency and microphone signal through modulation terminal generates FM modulation b PLL IC PLL IC is adjustable IC to produce the desired frequency which VCO provides through loop filter It has internal counter using 21 25MHz reference frequency to generate 6 25kHz as reference Signal VCO frequency from prescaled input is divided signal and compared with reference signal phase in phase comparator Built in charger pump changes voltage until two signals are in phase and charged voltage supplies VCO through loop filter to produce the desired frequency Frequency data associated with channel goes to PLL IC by CPU through
3. 2 1 GENERAL SPECIFICATIONS a Frequency Range 446 00625 446 09375 MHz b Output Impedance 50Q unbalanced c Modulation Type 8KOF3E d e f Channel spacing 12 5 kHz 9 Power 6 0V alkaline 4 8 V NiMH h Battery Life ALKALINE at 1000mAh gt 30 hours Tx5 Rx5 Stand by 90 i Operating Temperature 20 degrees C to 60 degrees C j Dimension 95 5 H x 50 W x 26 D mm k Weight 132 g with Battery Communication Mode semi duplex Channel Capacity 8 channels 2 2 ELECTRICAL SPECIFICATION a TRANSMITTER 1 Output power Max 500 mW 2 Frequency Stability 5 ppm 20 600 3 Modulation Method FM 4 Oscillation Method PLL SYNTHESIZER 5 Max Frequency Deviation 2 5 kHz with tone 7 Spurious Emission 36dBm 30dBm 8 FM Hum Noise 40dB 1kHz 6096 modulation w CCITT 9 Distortion 596 1kHz 6096 modulation 6 Cooling Method air cooling Method 10 Tx Audio Response 6dB OCT 3dB PRE EMPHASIS 300Hz 2 5kHz b RECEIVER 1 Receive Method Double Super Heterodyne 2 Receive Sensitivity 0 28uV 20dB SINAD w CCITT 3 Squelch Sensitivity 6 to 8 dB at 12dB SINAD 4 Bandwidth gt 3kHz 6dB ATT point 5 Selectivity 60dB 25kHz 6 Local Frequency Stability 5 ppm between 20 degrees C and 60 degrees C 7 Spurious Response 40dB 8 Audio output 200mW Internal 8 Ohms load THD 10 Ext 100mW 9 Distortion 5
4. 2 until the auto lock icon blinks and ALo appears in the LCD panel 8 Press the Up Button 10 or Down Button 11 to select the Auto option Press the ENTER key to confirm your selection If you do not press any key for more than 15 seconds in the standby mode all respective keys will automatically be locked To turn the auto key lock on or off in standby mode simply press and hold the Function Button 12 for more than 1 5 seconds To quickly activate the Auto Key Lock hold the Function Button 12 for more than 1 5 seconds 3 4 8 CALL RINGER MELODY SELECTION MODE This feature provides 7 user selectable call ringer melodies to alert you of a calling party To select your favorite Call Ringer melody press the Function Button 12 until the call icon blinks and CAL appears in the LCD panel 8 Press the Up Button 10 or Down Button 11 to preview the 7 available melodies Press the ENTER key to confirm your selection 4 SERVICE AND ADJUSTMENT 4 1 Frequency synthesizer PLL a Open the radio disconnect the antenna and connect apower meter And a 50 Ohms dummy load with the internal antenna connecting point of TECtalk b Check the voltage between TP amp GND in digital volt meter C Then set the low channel of TECtalk the lowest frequency d After pressed PTT key of TECtalk trim VC1 for adjusting the lowest frequency of Tx channel to DC 1 5V in the voltage of TP1 e After releasing the PTT key And
5. CLOCK DATA PLL IC enables by strobe line of CPU c Loop Filter Loop filter is composed of R48 R49 C84 C85 and forms pulses from pin14 Into to DC and eliminates harmonic components in pulses It helps VCO oscillate clearly as DC voltage is supplied into Varicap 5 2 RECEIVER This is composed of Dual Conversion Super Heterodyne First IF is 21 7MHz Local oscillator frequency is lower in 1 st IF than Rx frequency It is called low side injection Second IF is 450kHz 2nd local oscillator frequency comes to 21 25MHz a Rx Tx Conversion Circuit Rx signal goes to Rx Tx conversion circuit through FIXED antenna connector low pass filter L5 L6 L7 C42 C43 C46 C47 and receiver resonance circuit composed of L8 C1 When transmitting voltage through R25 L12 D6 supplies D7 of receive input is short and Tx is on condition When PIN diode is off in condition of Rx L8 and C1 resonate serially and make impedance matching at receiver bandpass filter SF1 b Front End Front End has Q1 to provide a high sensitivity and low noise feature It employs SAW filter as band pass filter to eliminate image frequency frequency and to produce enough pass band by Q1 input and output c Mixer Mixer has one base BFQ 67W Q2 to feature high low noise quality It has RF signal through L7 L8 SF1 SF2 and Q1 RF signal from Local oscillator mixed It develops 1 st IF 21 7MHz 1st IF goes to 1st IF amplifier Q3 KTC4080 base through X tal filter XF1 I
6. F of mixing signals is selected and enters the X tal filter Output impedance of mixer is direct matched with input impedance of X tal filter Matching of filter satisfies pass bandwidth of filter ripple elimination within the pass band and attenuation characteristic of stop band X tal filter is composed of two pole monolithic X tal filter with 8kHz of IF bandwidth R11 is used as impedance matching with 1 st IF Amp Q3 d IF AMP and Detection 1 st IF AMP Q3 supplies IF U12 mixer input pin16 through output resistor R13 and C21 to need gain in insertion loss of X tal filter and last stage circuit Multi use IF IC makes up of mixer IF AMP pint 2 nd local frequency enter to pin 1 It supplies mixer of internal IC Mixer output of IC through pin3 passes 450kHz ceramic filter supplies 2 nd IF amplifier and limits After 2 nd IF AMP has a process of enough gain and AM rejection it comes to quadrature detection Demodulated audio signal by T1 Quad Coil is amplified and comes out to pin 9 Detected audio signal through R22 VR1 and input in audio amp IC U4 through C22 e Squelch Circuit Noise component of detected outputs has amplification Squelch threshold is controlled by Resistor R18 C31 R15 f Audio Amplifier Demodulated audio signal enters to pin2 of U4 After above signal is amplified in U4 the audio output for the speaker is reached at pin 5 through C220 5 3 Transmitter When Tx starts with pressing PTT switch VCO o
7. Kommunikationstechnik aus Norddeutschland SERVICE MANUAL 2 WAY PORTABLE HANDHELD PMR RADIO TECtalk Jan 2000 CONTENTS 1 GENERAL 1 1 General 1 2 Characteristics and features 2 SPECIFICATION 2 1 General Specification 2 2 Electrical Specification 3 OPERATION 3 1 Push buttons 3 2 ICONS 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 amp corrections 5 DESCRIPTION OF RADIO CIRCUIT 5 1 Frequency Synthesizer 5 2 Receiver 5 3 Transmitter 6 CHANNEL DATA 1 GENERAL 1 1 GENERAL TECtalk is a minimum sized two way portable handheld radio The frequency range is 446 00625 446 09375MHz 8 UHF operating channels according to European PMR 446 international agreement are available 1 2 CHARACTERISTICS AND FEATURES a All active devices in this radio are semiconductors and high density IC b The radio is designed very compact and the weight is approximately 140g including battery c The unit is equipped with CPU HD404889 from HITACHI d Power supply is designed for battery operation with 4 cells alkaline 1 5V AAA batteries or 4 cells rechargeable NiMH batteries of the same size e The radio is shipped with fixed non detachable rubber duck antenna and belt clip and carrying strip It comes without batteries Other equipment is optional 2 SPECIFICATION
8. dby mode press the Up Button 10 briefly to move to the next higher main channel number Press the Down Button 11 briefly to move to the next lower main channel number 3 4 2 CTCSS Coded Tone Controlled Squelch System SUB CHANNEL SELECTION MODE This feature allows you to have more privacy on the main channel by using tone codes international numbering system 00 38 within a main channel This enables you to communicate with Your partners on the same main channel when all partner stations use the same subcode This helps to avoid congestion on the main channel and filters out unwanted noise static and other stations using different codes There are 38 CTCSS subchannels for each main channel To change the CTCSS subchannel Press the Function Button 12 until the word cTc appears in the LCD Panel 8 Press the Up Button 10 or the Down Button 11 to choose the desired subchannel to use The corresponding subcode frequency will be displayed in the lower right corner Press the Enter Button 13 to confirm your selection NOTE To communicate with other PMR units they must be switched to the same channel and CTCSS subcode To communicate with other LPD units that do not have subcodes switch your unit to the same channel with the subcode set to OFF 3 4 3 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 p
9. er should be in the limit of 2 5 kHz d Spectrum Test 1 terminate antenna output with 50 Ohms and use a power attenuator of 20 dB to avoid harmonics generated by analyzer overload be 20dB more 2 observe the spectrum with pressing PTT key The harmonics should be less than 36 30 dBm with 20 dB external attenuator the reading will be 56 30 dBm 4 4 RECEIVER a Preparation 1 Adjust the power supply to DC 6 0V 2 Adjust Voltage level to 0 7Vrms at 8 Ohms speaker output load after power on b Connection method 8 Ohms LOAD OSCILLOSCOPE POWER SUPPLY DISTORTION METER SINAD METER c Signal generator Adjustment for RX sensitivity test 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 set RF level to 47dBm d Check and adjust Squelch sensitivity 1 Set the standard channel 2 In squelch mode SQ volume RV1 must be turned counterclockwise to open the squelch 3 After adjusting SSG to channel frequency the RF level of SSG is set so that a SINAD of 8 6dB is obtained Turn potentiometer carefully so that Squelch just opens at that point 4 5 RECEIVER TEST a Rx sensitivity test SSG should be adjusted to 12dB of SINAD s point needle Observe waveform of oscilloscope at signal generator signal modulated with 1kHz audio and 1 5 kHz frequency deviation The 12 dB Sinad point sh
10. gth 9 Power Save Display Ee Blinks when the power save is activated The rate at which the icon blinks varies with the power saving ratio Fast indicates a lower power saving while slow indicates a higher Power saving ratio 10 Tx Indicator Zz Appears when a signal is being transmitted 11 Rx Indicator Appears when a signal is being received 12 Large Segment Display m ER EN ne ye i Indicates the channel number in use at the normal mode 2 23 When the Function Button is pressed it displays the function menu in sequence CH SC aW UO Udt ALo CAL ton 13 Small Segment Display rt mm rt LL LC EL Displays the CTCSS tone option at the normal mode CTCSS option is displayed in Hz Displays the SUBMENU of each MENU in the function mode e g CH 1 69 SC up dn dW channel number UO high off low Udt 5sec 3sec 2sec 1sec ALo off auto CAL number 1 7 ton no Freq 3 3 Key Function 3 3 Key Functions 3 3 1 ENTER BUTTON 13 1 Short Touch Power On Press this button 13 briefly to turn the unit on A short confirming melody will play 2 Long Touch Power Off Press this button 13 for longer than 1 5 seconds to turn the unit off Note Press it to confirm the required option for respective functions during function edit mode 3 3 2 FUNCTION BUTTON 12 1 Short Touch Press this button briefly to enter function edit mode in standby
11. he green Rx LED Indicator on the left side of the LCD Panel 10 will be on Call Tone Transmission Press the PTT Button twice quickly to call another party on the same channel The word CALL and the Tx icon will appear in the display The user selected call ringer melody will play 3 3 6 MONITOR BUTTON 2 Press it to check activity on the current channel before you try to transmit Adjust the Volume Control 10 11 if necessary When you press the Monitor Button the LCD Panel 8 will be illuminated with an amber color back light and both the Tx and Rx LED Indicators will be on If you press the Monitor Button during the function edit mode you will return to standby mode directly 3 3 7 EXTERNAL MIC SPEAKER 6 This jack accepts an optional headset microphone for totally handsfree operation Please refer to the user manual or Albrecht catalogue See also section regarding VOX SELECTION MODE 3 4 Setting and Operation 3 4 1 BASIC CHANNEL SELECTION In order to communicate with other PMR units both you and the receiving party must be on the same channel Tectalk has 8 channels 1 8 as indicated by the large digits in the LCD Display Panel 8 Before trying to transmit on the selected channel you should press the Monitor Button 2 to check the activity on that channel If someone is already on the selected channel you should try another channel which is not occupied To change the basic channel in the stan
12. mode 2 Long Touch Press for longer than 1 5 seconds to activate the KEY LOCK in the standby mode Please note all buttons will be disabled except the Monitor Button 2 and PTT Button 4 will remain fully operational 3 3 3 UP BUTTON 10 1 Short Touch In the standby mode press this button briefly to move to the next higher main volume level In the function edit mode press briefly to shift from the current option in each submenu to the next option in the same submenu 2 Long Touch Pressing this button for more than 1 5 seconds will allow you to navigate at a more rapid rate through different volume level in the standby mode or through different menus in the function edit mode 3 3 4 DOWN BUTTON 11 1 Short Touch In the standby mode press this button briefly to move to the next higher main volume level In the function edit mode press briefly to shift from the current option in each submenu to the previous option in the same submenu 2 Long Touch Pressing this button for more than 1 5 seconds will allow you to navigate at a more rapid rate through different volume level in the standby mode or through different menus in the function edit mode 3 3 5 PUSH TO TALK PTT BUTTON 4 Press it firmly and speak into the Built in Microphone 9 to transmit The red Tx LED Indicator at the right side of the LCD Panel 8 will be on Release it to revert to standby mode When an incoming call is received t
13. n 4 without using the PTT button To access the VOX Selection menu Press the Function Button 12 until the VOX icon blinks and UO appears in the LCD Panel 8 Press the Up Button 10 or the Down Button 11 to select from high low or off High or low setting determines VOX response sensitivity Press the Enter Button 13 to confirm your selection To turn off the VOX feature enter the VOX selection mode and then select Off 3 4 6 VOX RECOVERY TIME SELECTION MODE This allows the response characteristics of the VOX function to be precisely adjusted to suit individual needs To access the VOX Recovery Time Selection menu press the Function Button 12 until Udt appears in the LCD Panel 8 with the VOX icon blinking Press the Up Button 10 or the Down Button 11 to select from 5 3 2 or 1 second setting This setting determines the delay time between transmitting and receiving Press the Enter Button 13 to confirm your selection Please note you may need to try different VOX time settings to determine the best value to suit your speaking habit To turn off the VOX feature enter the VOX selection mode and then select Off 3 4 7 AUTO KEY LOCK SELECTION MODE This feature prevents accidental channel change and disturbance to the preferred settings of the Communicator Auto Key Lock temporarily disables the Up Down and Enter Buttons To access the Auto Key Lock Selection menu press the Function Button 1
14. ould be reached with an RF level of 110 to 107Bm This is a good sensitivity b Audio Distortion Test 1 SSG should be adjusted like way of point a and RF level set to 47dBm 2 Adjust to 0 7Vrms at 8 Ohms load observing audio wave form 3 Read the needle of distortion meter it should be less than 5 distortion c Squelch Test After RF level of SSG should be set to the lowest level RF level should be gradually increased until speaker makes audio sound At this point check RF level Check if the SINAD is 8 6 dB Check that squelch will close when Level is reduced to minimum If not readjust RV 1 and check again 4 6 Symtoms Check point amp Correction a Diagnosis method 1 Check each switch to work well 2 Check voltage of battery 3 Problem whether problem comes from transmitter or receiver b Troubleshooting a Transmitter Power key is on condition but does not work Battery could completely be discharged Battery cell wrong inserted Contact problem between Battery and Radio Fail to transmit Run out of battery or charge problem Fault of PTT key Fault of Q4 Q5 Transmitter works but frequency is unmatched defective frequency synthesizer defective X tal X2 No audio modulation Tx power and Tx frequency are normal Problem of microphone or mic connector IC U7 problem Tx is set when switch is on r3 r3 Tx switch problem
15. ress the Function Button 12 until the auto channel icon blinks and SC appears in the LCD Panel 8 Press the Up Button 10 or the Down Button 11 to choose scanning up or down from the current channel number Press the Enter Button 13 to confirm your selection 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 8 To turn off the auto channel scan feature in the standby mode simply press the Function Button 12 once 3 4 4 DUAL WATCH SCAN MODE This feature allows you to monitor two different channels at the same time If you pre set any priority channel other than the current channel in use the pre set channel will be scanned every 0 5 second and signals you when a call is received To access the Dual Watch Scan menu Press the Function Button 12 until the dual watch icon blinks and dW appears in the LCD Panel 8 Press the Up Button 10 or the Down Button 11 to select the desired channel number you wish to closely monitor Press the Enter Button 13 to confirm your selection To turn off the dual watch feature in the standby mode simply press the Function Button 12 once 3 4 5 VOX SELECTION MODE The Voice Activated Transmission VOX function allows your voice to activate transmission automatically when the Communicator is used with an optional handsfree mic headset or even with the built in Microphone tto
16. then check if the highest frequency of Rx channel is within DC 1 0V in the voltage of TP 4 2 TRANSMITTER a Connect EUT amp measure equipment according to block diagram below POWER SUPPLY MODULATION METER OSCILLOSCOPE AV VTVM DISTORTION METER SPECTRUM ANALYZER FREQUENCY COUNTER POWER METER DUMMY LOAD AF OSCILLATOR b C d e Connect DC 6 0V voltage preset to EUT Connect power meter amp dummy load 50 Ohms Adjust Tx frequency according to trimming trimmer VC2 wor 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 9 Checking oscilloscope and modulation meter max frequency deviation should be in 2 5 kHz 4 3 TRANSMITTER TEST a Output Power Test power 6 0V DC should be Max 500mW and in 50 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 300Hz to 3kHz Check the audio level for 300Hz to 3kHz based on frequency 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 met
17. utput amplifies through Q4 Q5 transmits by antenna through low pass filter Tx RF signal produced from Tx VCO is amplified by DRIVER Q5 through C53 and entered Q4 POWER TR input terminal with final amplification After this stage the signal is emitted at antenna through 50 Ohms matching circuit to low pass filter L7 L6 L5 C42 C43 C44 C46 C47 to eliminate harmonics 5 3 1 Audio Modulation and Audio Amplification Audio signal produced by external or internal microphone is amplified and limitted by IC U7 The output signal enters to VCO through low pass filter and U2 Max Frequency modulation deviation is adjusted by VR1 Audio modulation and audio amplification has preemphasis characteristic of 6dB OCT by U7 NJM324V 11 CHANNEL DATA CH Frequency MHz CH Local Oscillator MHz 1 446 00625 1 424 30625 2 446 01875 Lo 424 31875 3 446 03215 Lt 424 33215 4 446 04375 DEN 424 34375 446 06875 e 424 36875 7 446 08125 MES 424 38125 446 09375 MEF 424 39375 5 44605608 5 42435625 Copyright Albrecht Electronic GmbH amp Jcom Ltd Jan 2000 Albrecht Electronic GmbH Dovenkamp 11 22952 L tjensee All service documents can be downloaded for service purpose from http www albrecht online de Service Hotline 49 4154 849 180 Service Fax 49 4154 849 288 E mail service albrecht online de
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