Panasonic KX-TC2106UAB Service Manual

Panasonic KX-TC2106UAB Service Manual Manual pdf 36 page image

14.6. Transmitter/ReceiverBase Unit and Handset mainly consist of RF (Radio Frequency) IC and CPU.Base Unit and Handset transmit/receive voice signal and data signal through the antenna on carrier frequency.Signal Path:*Refer to CDL TX/RX in SIGNAL ROUTE (P.41).14.6.1. Base to HandsetCircuit Operation:The voice signal input from the TEL LINE interface goes to RF IC as shown in BLOCK DIAGRAM (BASE UNIT) (P.31).In the talk mode (off-hook) condition, the telephone line voice signal passes through D303, Q301, C313, R320 and C315.The signal goes through the compressor of RF IC, and it is output to transmitter circuit.The signal of the data sent to the handset is applied in the anode of the variable capacitor diode (VARICAP : DV401).The capacitor of VARICAP is changing in accordance with the voice signal from telephone line interface or TX DATA signal fromCPU. Therefore, the carrier frequency which is generated by TX VCO will be changed, and Frequency modulated RFsignal is generated and amplified by RF AMP (Q405, T403). It passes through the Duplexer DPX401 and is radiated fromAntenna.The signal is transmitted from the base unit and received by the handset antenna and amplified by RF amplifier (Q801) throughDPX1 as shown in BLOCK DIAGRAM (HANDSET) (P.38). And then it is converted to 10.7 MHz and 450 KHz Intermediatefrequency by RF IC and related components.The demodulated audio signal is output from RF IC (DET OUT) and passed through "Expander" process to reduce noise, thenvoice signal amplified by "Receiver amplifier" is output to receiver (REC1).The receiver loudness is adjustable by using "LOUD" key on the handset.TX data (to Handset):CPU (VTX) becomes low to turn on the transmission power transistor Q805, and CPU (TX-data) sends data signal. It isFM-modulated by TX VCO and driven by RF AMP, then transmitted to the handset.14.6.2. Handset to BaseCircuit Operation:The voice signal from the handset user is picked up by the microphone (MIC), then it passes through "Compressor"process to reduce noise as shown in BLOCK DIAGRAM (HANDSET) (P.38). And the voice is FM-modulated byVARICAP (DV1).The carrier frequency is generated by TX VCO. The transmitter power transistor Q805 is turned on/off by CPU (VTX).The carrier signal is amplified by RF AMP and sent to the handset duplexer and antenna.The signal of 39 MHz band (39.775~40.000 MHz) which is input from ANT is filtered at DPX401 as shown inBLOCK DIAGRAM (BASE UNIT) (P.31), then it is input to RF IC.The signal input to RF IC is converted through Mixer inside of RF IC, RF filter (CF1, CF2) and Expander.The signal is transmitted from the handset and received by the base unit antenna and amplified by RF amplifier Q401, thenit is converted to10.7 MHz and 450 KHz Intermediate by RF IC. The demodulated audio signal is output from RF IC(DET OUT) and passed through "Expander" process to reduce noise, then voice signal is led to LINE AMP. The signal passesthrough TELEPHONE INTERFACE and Tel-line.RX data (from Handset):The data signal from handset (ex: Talk, ACK, COM) is also included in 39 MHz band same as the voice data. After second iffilter, the data signal is made square shape by data limiting AMP of the RF IC. RX data is output to CPU (RX Data).36KX-TC2106UAB / KX-TC2106UAS / KX-TC2106UAT / KX-TC2106UAW