TECHNICAL MANUAL FOR COMPACT VHF DSC RM2042

5 CIRCUIT DESCRIPTION AND SCHEMATIC DIAGRAMS RM2042CH70 CARRIER VHF CARRIER AF SIGNAL MODULATION REMARKSDETECT DETECT DETECT DETECTNo carrier detected at CH70 receiver,0 0 0 0 and no carrier detected at ext. VHF.Af signal detected because of noise.0 0 1 0 Non existing combination.No carrier detected at CH70 receiver,0 1 0 1 byt carrier detected at ext. VHF.AF signal detected from ext. VHF.No carrier detected at CH70 receiver,0 1 1 0 but carrier detected at ext. VHF.No AF signal detected from ext. VHF.Carrier detected at CH70 receiver,1 0 0 1 and no carrier detected at ext. VHF.AF signal detected from CH70 receiver.Carrier detected at CH70 receiver,1 0 1 0 and no carrier detected at ext. VHF.No AF signal detected from CH70 receiver.Carrier detected at CH70 receiver,1 1 0 1 and carrier detected at ext. VHF.AF signal detected from CH70 receiver.Carrier detected at CH70 receiver,1 1 1 0 and no carrier detected at ext. VHF.No AF signal detected from CH70 receiver.5V SUPPLYThe 5V supply is generated from the battery voltage by the series voltage regulator U11.This regulator is of the type 78L05AC, which is able to deliver a current of about 50mA without any heatsink.10V SUPPLYThe 10V supply is generated from the battery voltage by the series voltage regulator U10, which is of thetype LP2951C. The output voltage is determined by four feed back resistors (R121 to R124) and isadjustable by means of the trimming resistor R124.The LP2951C has a build-in facillity for generating an error signal, when the output voltage drops morethan 5% with respect to the programmed output voltage. This error signal is watch every one milli secondby the microprocessor to ensure a controlled power down sequence.PAGE 5-189341