Kenwood VGS-1 Service Manual
Also see for VGS-1: Service manual
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VGS-13CIRCUIT DESCRIPTIONOOIIIC57VGS-1 External device5V5VPull-upresistorPull-upresistorFig. 3 External device, pull-up resistor■ AI Input PortIf input exceeds 100mVp-p, the input signal is clipped anddistortion occurs.It is necessary to make setting so that no signals exceed-ing 100mVp-p are input.If the input level lowers, S/N decreases, so the maximuminput not exceeding 100mVp-p must be used.■ AO Output PortWhen recording is performed with a 100mVp-p input, theplayback output becomes an approx. 2.8Vp-p level.If Prerecorded Voice is generated, the output is approx2Vp-p.Beat Shift CircuitTo prevent VGS-1 clock oscillation for the MCU (IC2) fromcausing spurious reception to transceivers to which VGS-1 isconnected, the clock oscillator (11.0592MHz) has a beat shiftcircuit with a transistor switch (Q1).■ Beat Shift Circuit OffPin 94 of the MCU (IC2) goes Low level, Q2 turns off, andQ1 turns on because a 5V bias is applied to its base. In thiscondition, C10 is shorted, so the oscillation frequency is un-changed.■ Beat Shift Circuit OnPin 94 of the MCU goes High level, Q2 turns on, and Q1turns off because its base is pulled down to GND. In thiscondition, C10 is connected in series to the crystal oscillatorand the oscillation frequency increases by approx. 150ppm.Fig. 4 Beat shift circuitAmateur Transceiver IdentificationThe VGS-1 can be set as an amateur transceiver or a LandMobile Radio transceiver in the factory.When it is used as a Land Mobile Radio transceiver, inter-nal data in the VGS-1 is changed to suit the Land Mobile Ra-dio transceiver, so it cannot be used as an amateur trans-ceiver.The VGS-1 set as a Land Mobile Radio transceiver can beidentified because the RV4 land on the PCB is at High level.The default is Low level.C10X1Q1Q2R19R18C11C12R175VIC2 94 pinPA1High : NormalLow : Shift6667XTAL EXTALIC2MCURV1RV2RV3RV4Accessory unitFoil side viewFig. 5 RV4 |
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