AES Cor por at i on AES 285 Newbury St reet I nt e lliN e t Peabody,MA 01960- 1315 USA Phone 978- 535- 7310 Fax 978- 535- 7313 I nf o@aes- i nt el l i net . com SERVICE MANUAL MODEL 7 0 8 8 - UE Rev 1.
TAB L E OF C ONTE NS 1.S PE C IF IC AT ION 2.C ONNE C T IONS AND OPE R ATION 3.PE R F OR MANC E TE S T AND AL IG NME NT 4.T E S T E QUIPME NT C ONF IG UR ATION 5.T R ANS MIT T E R PE R F OR MANC E TE S T 6.T R OUB L E S HOOTING 7.C IR C UIT D E S C R IPTION 8.PR OG AMME R INS TR UC TION 9. PARTS LI ST 10. PRI NT CI RCUI T BOARD LAYOUT 11. COMPONENT PLACEMENT 12.
1.S PE C IF IC ATION G E NE R AL S PE C IF IC ATIONS POWE R S OUR C E … … … … … … … … … … … … … … … … … … +13.8V D .C .nominal(+10.8 to +15.6V ) TE MPE R AT UR E R ANG E S T OR AG E … … … … … … … … … … … … … … … … … … 80℃ maximum -40℃ min. 25℃ nominal OPE R AT ING … … … … … … … … … … … … … … … … … 60℃ maximum -20℃ min.
2.C ONNE C TIONS AND OPE R ATION E X T E R NAL C ONNE C TIIONS 1-50Ω B NC S OC K E T 2-9 WAY "D " T Y PE PL UG (D _S UB ) 1 2 D- TYPE I NTERCONNECTI ONS PIN F UNC T ION TY PE R ANG E D E S C R IPTION D _S UB -1 D ATA_IN ANAL OG UE 100Mv-2.5V P-P E X TE R NAL MOD UL ATION INPUT D _S UB -2 D ATA_OUT ANAL OG UE 1V P-P R E C E IV E R AF OUTPUT D _S UB -3 PTT INPUT 0V / +5V TR ANS MIT E NAB L E D _S UB -4 G ND G ND 0V G ND D _S UB -5 B+ V+ +13.
3.PE R F OR MANC E TE S T AND AL IG NME NT The alignment and performance test procedures assume the use of the following equipment D iscrete test equipment V olt Meter S pectrum Analyser and notch filter(option) R F Power Meter.
20dB Attenuator Audio G enerator Modulation Meter S INAD Meter R AD IO OS C IL L OS C OPE V OL T Meter S pectrum Analyzer D C Power S upply F requency C ounter T est B ox 123.45678 Test E quipment C onfiguration 5.TR ANS MITTE R PE R F OR MANC E TE S TS Power Output 1. S et the power supply voltage to 13.8V dc.and monitor the voltage during transmit. 2. S witch data radio T X and check and record the output power.Th e nominal output.
power is adjustable between 1 and 5W depending on the programming. 3. S et the PTT switch to OF F . Peak D eviation 1. C onnect the oscilloscope to the output of the modulation meter. 2. S et the AF signal generator to 100Hz at 5V peak -to-peak and connect to D ATA_IN L ine (pin 1 of D _S UB ) 3. S witch data radio to T X and observe the oscilloscope display to check that the 100Hz tone is a square wave. 4. Using the AF signal generator,sweep from 100Hz to 3K Hz and record the peak deviation. 5.
are with respect to ground. C areful alignment,using suitable test equipment,and quality interface cables should ensure that the radio meet their specified performance. V oltage C harts Measurement C ondition:455.5MHz,13.8V supply,R X C arrier Present. Transistors. R ef. No. RX TX B C E B C E T101 0 0 0 0.44 2.5 0 T871 4.96 0 4.97 4.3 2.3 4.9 T323 4.5 4.7 3.8 4.5 4.7 3.8 Integrated C ircuits R E C E IV E R Pin U621 U401 U240 1 1.35v 4.7v 4.
2 0v 4.7v 3.8v 3 0v 2.3v 3.3v 4 0v 0v 4.5v 5 6.9v 1.59v 4.1v 6 13.7v 1.59v 4.1v 7 6.9v 0v 0.6v 8 1.35v 0.65v 0.6v 0v 0.9v 10 4.58v 4.5v 11 0v 3.6v 12 4.96v 2.2v 13 4.96v 0v 14 0v 0v 15 0v 0v 16 0v 0.9v 17 0v 18 0v 19 4.6v 20 4.6v 9 Integrated C ircuit V oltages(R eceive) Integrated C ircuits T R ANS MIT PIN U701 U607 1 0.1v 1.
2 9.1v 1.1v 3 8.9v 1.1v 4 0v 0v 5 0.4v 1.1v 6 0.2v 1.1v 7 12.4v 1.1v 8 13.7v 2.
y Audio amplifier connection from D _S UB pin 1 y F requency S ynthesiser y Transmitter y Automatic Power C ontrol Audio frequency connections Processed data from the U601A is applied to the V C O via V R 52 1 F requency synthesiser circuit With data received from the E E PR OM (U911) the frequency synthesiser circuit controls and Produces the R F carrier frequency for the transmitter durin g transmit and the local oscillator frequency for the receiver.
TC X O DC supply U401 PL L D ata C harge Pump L oop F ilter TX OR R X VCO R F Out 12.8MHZ V C TC X O The reference oscillator comprises V R 421,C R 2(12.8MHZ)and associated resistors and capacitors. C R 2 provides the reference oscillator frequency and the temperature compensation that ensures that the frequency remains stableacross the temperature range(typically± 2.
T he V C O comprises T 321,C oil L 320,and varactor D 303 D 302.D 303、D 302 produces a change in frequency with a change in D C voltage and is controlled by the tuning voltage signal present at the cathode.The local oscillator programmable dividers.D ATA is received by U401 at pin 12 from pin 13 of U401. The R F signal at the collector of T 321 is applied to an amplifier/ buffer T322.The amplified S ignal from T322 passes to the prescaler,U401 pin5.
The signal is filtered by the loop filter (R 403,E 402 and E 403)to remove any residual reference F requency harmonics from the signal.After filtering the signal is applied to the voltage controlled Oscillator module. D ual modulus prescaler The prescaler divides the V C O frequency by 64 or 65.
The output signal is passed from T 105 to T 107 via a matching network consisting of Inductor L 119 and C 119. R F power Amplifier The signal is then amplified for transmission by T107,which is a R F power amplifier. L ow pass filter The amplified R F signal is passed through the C AP coupler and is fed to the harmonic low pass filter,comprising L 112、L 113、L 114、L 118、C 147、C 149、C 150、C 151、C 154、C 155 and then to the antenna connector(ANT ).
IF Amp S econd Mixer L ocal Oscillator D ata Out Audio F ilter IF F ilter FM L imiterD iscnminator S quelch C ircuit Antenna S witch In receive,the diode D 101 and D 102 are reverse biased.L 110 is now in circuit,passing the signal from the antenna to the front end without signal loss. F ront E nd T he receiver signal is routed to T 201.It passes through the band pass filter consisting of L 204、 L 202、L 203 to T202. D iode D 103 serves as protection from R F overload from nearby transmitters.
The input signal is conpled to the base of T 201 which serves as an R F amplifier. The output of T201 is then coupled to a second bandpass filter consisting of C 211 to C 212,L 206 L 207. The output of the T201,is then coupled to the double-balanced mixer T202. The receiver front end module is factory pre-tuned and requires no adjustment. R epair is effected by replacement of the entire module.
R eceiver Audio C ircuit and the Mute(S quelch)C ircuit. R S S I C ircuit Any noise signal is amplified by U240 internal noise amplifier.S ignal is applied to pin12 of U240 The squelch trigger output(pin 14,U240)is applied to the pin 6 of D _S UB . When noise is present,the voltage at pin 12 of U240 is exceeds 1 V .The squelch trigger output is 0V (logic 0)It's mak e pin 6 of D _S UB open state. When no noise is present,the voltage at pin 12 of U240 is less than 1V and pin 14 of U240 IS AT 5v(logic 1).
Power supply circuit The data radio is supplied with a nominal +13.8V dc power supply input from external equipment which is filtered using C 805,L 801 and C 804. Tuning up procedure Transmitter Alignment Automatic Power Adjustment Transmit periods longer than 3 minutes are to be avoided. 1. S witch to data radio to T X . 2. S elect High power setting. 3. R ecord the transmit power set. 4. S witch the data radio to transmitter OF F .
F requency accuracy 1. Whilst transmitting,measure the transmit frequency using the R F frequency counter. 2. On the V C TC X O PC B ,adjust trimmer resistor V R 421 so that frequency is as close as possiable to the exact required transmit frequency.Ideally it should be within 100Hz at room temperature. R eceiver Alignment Important note:B efore setting up the receiver it is importan t to check the frequency accuracy alignment is correct as described in the transmitter alignment section. R F tuning 1.
7. Whilst observing the oscilloscope,adjust the deviation and balance potentiometers.V R 521 to obtain a good square at the following deviation: 12.5K Hz channel spacing<=2.5K Hz dev 25K Hz channel spacing<=5K Hz dev 8. It may be necessary to alternate the adjustment of the two potentiometers. 9. S weep the signal generator between 100Hz and 3K Hz.R ecord the peak deviation. The peak deviation should be as above.If necessary adjust the potentiometers to achieve this. 10. S witch to R X .
2. press ‘ read from radio’ button，then it will read channel data from radio. 'Read from radio' buttorn 3.
4. finished reading data of radio。 press OK button when finished reading data of radio 5. then getting into function setup . F irst , select 'parameter amendment' .
6.If you alter the parameter of 'high power', the output power of radio will be changed, eg. The 255 is the highest power,the 0 is the lowest power Press the 'write to radio' button ,then changed parameter will be saved to radio selecting 160 in the high power box ,you can set 2w output power. carrier wave time scan mode 1.carrier wave 2.time time-lapse time channel mode 1.priority channel scan 2.
only the data in those two box is different ,can the highpower and lowpower be set.for example,if you set 100 in the box of highpoer and lowpower in the same time ,the computer will default the hightpower.
