Motorola Vhf 136 174 Mhz Uhf 435 480 Mhz 6881096c38 Manual
Here you can view all the pages of manual Motorola Vhf 136 174 Mhz Uhf 435 480 Mhz 6881096c38 Manual. The Motorola manuals for Portable Radio are available online for free. You can easily download all the documents as PDF.
Page 91
6881096C38March, 2006 UHF (435-480 MHz) Band Information: Theory of Operation 8-5 7. The radio restores last power up state (i.e. state before the radio was turned-off). 8. Power is supplied to PLL circuitry. 9. Power is supplied to Rx and Rx VCO circuitry. 10. CPU sends data to PLL circuitry. If LOCK status is confirmed, radio continues the power-up sequence. Otherwise, PLL ERR is displayed. 11. Squelch level is checked. 12. If the Rx audio level is less than the pre-programmed squelch level, and other...
Page 92
March, 20066881096C38 8-6UHF (435-480 MHz) Band Information: Theory of Operation 8.3.5.3 Synthesizer The frequency synthesizer is a large-scale monolithic synthesizer integrated circuit Q323. The synthesizer IC contains a dual modulus prescaler, programmable divide-by-N counter, prescale control (swallow) counter, reference oscillator, reference divider, phase detector, charge pump and lock detector. Also, included in Q323 are shift registers and control circuits for frequency controls and general...
Page 93
6881096C38March, 2006 UHF (435-480 MHz) Band Information: Theory of Operation 8-7 8.3.7 Power Control Output power is controlled by the CPU (Q101), the D/A converter (Q121), the dual Op-Amp (Q419), which is used as a differential amplifier and comparator. Current is sensed by the voltage drop across R445. When the radio is in high power mode, this voltage is compared to the D/A converter voltage at 5-watt. When the radio is in low power mode, this voltage is compared to the D/A converter voltage at...
Page 94
March, 20066881096C38 8-8UHF (435-480 MHz) Band Information: Theory of Operation 8.3.8.3 Mixer The mixer is a DBM type (L407, L408, Q407). The mixer LO frequency is 45.1 MHz above the desired receiver frequency. When the receiver frequency is present, the mixer output will be a 45.1 MHz signal. The mixer output is peaked for 45.1 MHz at L410, C432 and R413, and the signal is filtered by crystal filter F402 and amplified by Q408 before being sent to the input of the IF IC Q506. The 45.1 MHz IF signal...
Page 95
6881096C38March, 2006 UHF (435-480 MHz) Band Information: Block Diagrams 8-9 8.4 Block Diagrams 8.4.1 Complete Figure 8-2. SAVE 5VRX 5V DAC RX Key Pad Power Input TX 5V BATTERY 5VDAC RXDAC TX 35 DTMF IN RC NETWORK 9 RC NETWORK 3 MIC M101CN701 CN101 27 31 4 15 16 22 25 2522 15 163 4 319 35 27 DAC TX+ SW B 5VSPK SP701 (1/2) DTMF IN Detect Detect 13 13 ANT ANT Switch Q409,410 RF AMP Q404 Mixer Q407Local Buffer Q416 2-Pole Crystal Filter F402 Buffer AMP Q414 Pre Driver Q413 Power Control Q419 Power SW...
Page 96
March, 20066881096C38 8-10UHF (435-480 MHz) Band Information: Block Diagrams 8.4.2 Controller Figure 8-3. 8.4.3 VCO Figure 8-4. Key Pad 35 RC NETWORK 9 RC NETWORK3 MIC M10127 31 4 15 16 22 25 13 EEPROM Q114 CPU Q101 PTT S102Mon S101LCD LC101Shift Q102Xtal 8.38MHz X101 Restart Q133-Q138 Reset Q105 DA Converter Q121 CPU Pin87 DIODE Q126 CPU Pin21CPU Pin22 CPU Pin36 DC AMP Q125 CN101 RX Local Buffer TX BufferDATA Audio Sub Audio TX/RXSW CONTLRipple Filter Q318 5V VCO Buffer Q308RX VCO Q311 Q302 TX/RX...
Page 97
6881096C38March, 2006 UHF (435-480 MHz) Band Information: Block Diagrams 8-11 8.4.4 Transmitter Figure 8-5. 8.4.5 Receiver Figure 8-6. ANTTo Receiver TX +B +B TX 5V DAC RX Power Control Q419ANT Switch Q409,410 Buffer AMP Q414 Pre Driver Q413P in VCO Final AMP Q411PA Q412 Hamonics Filter C440-445, L415, 416 Matching Network C491-493,C435-437 L418,419 Coupler R445 DAC TX DAC RX From VCOFrom ANT Switch 2-Pole Crystal Filter F402 2nd Local 44.654MHz X5016 Pole Ceramic Filter F5016 Pole Ceramic Filter...
Page 98
March, 20066881096C38 8-12UHF (435-480 MHz) Band Information: Troubleshooting Charts 8.5 Troubleshooting Charts Figure 8-7. Troubleshooting Flow Chart for Receiver Start Very low or no 12 dB SINAD Noise at spkr when radio is unsqu’d? Is 1st LO at C431 >2 dBm? Inject on channel signal at RF port, C429 12 dB SINAD -105 dBm? Inject a 45.1 MHz signal at R467 12 dB SINAD 1Check IFIC Q506 (see below) Noise at pin 9 of IFIC Q506? Check VCO/Synth Inject on channel signal at C402 Check harmonic filter and...
Page 99
6881096C38March, 2006 UHF (435-480 MHz) Band Information: Troubleshooting Charts 8-13 Figure 8-8. Troubleshooting Flow Chart for Transmitter Start No Power +5VTX and TXB+ OK? Is current OK? Is DAC TX High or Low? Is Pin OK? Check Q201, Q202,Q206 & Q209 Check Voltages in Power Control Circuit Check Vo l t a g e s i n PA Line-upTroubleshoot VCO DoneIs Power OK? 1. Check Pin Diodes 2. Check Harmonic Filter Inspect/Repair TX Output Network NO NO LOW HIGH YES NO NO YESYESYESIs Check Pin to Q419 Pin 1
Page 100
March, 20066881096C38 8-14UHF (435-480 MHz) Band Information: Troubleshooting Charts Figure 8-9. Is information from µP Q101 correct? Is Q330 corrector AT4.65 VDC? Is Q314 Emitter AT=13VDC Is Q310 Pin 2 4.3 VDC in TX? Troubleshooting Flow Chart for Synthesizer Start Vi s u a l check of the Board OK?Correct Problem Check 5V Regulator +5VQ323 at Pins 3, 4Is 14.4MHz Signal at Q323 Pin 1?Check X301,C337,C338,C336 Are signals at Pin’s 8 of Q323 ? Check Q301, L303,C303,R301, C304 & R302Fix...