Kenwood TK-2180 Service Manual

Also see for TK-2180: Specifications Brochure & specs Instruction manual Instruction manual Pricing and specification manual

TK-218071. OverviewThis transceiver is VHF/FM portable transceiver designedto operate in the frequency range of 136 to 174MHz.2. Circuit Configuration by FrequencyThe receiver is a double-conversion superheterodyne witha first intermediate frequency (IF) of 59.85MHz and a secondIF of 455kHz. Incoming signals from the antenna are mixedwith the local signal from the PLL to produce the first IF of59.85MHz.This is then mixed with the 59.395MHz second local oscil-lator output to produce the 455kHz second IF. This is de-tected to give the demodulated signal.The transmit signal frequency is generated by the PLLVCO, and modulated by the signal from the microphone. It isthen amplified and sent to the antenna.3. Receiver System3-1. RF unitAn incoming RF signal from the antenna terminal ispassed through the antenna switch (D106, D107, D211 andD213 are off) and then the bandpass filter (L215, L216). Thebandpass filter is adjusted by a variable capacitor. The inputvoltage to the variable capacitor is regulated by the voltageoutput from the D/A converter (IC605). The signal is ampli-fied by RF amplifier (Q207), and passed through the band-pass filter (L211, L214).The resulting signal is applied to the first mixer (Q206),where it is mixed with the first local oscillator signal outputfrom the frequency synthesizer to produce the first IF(59.85MHz).3-2. IF unitThe first IF signal is passed through a four-pole monolithiccrystal filter (XF200) to remove a adjacent channel signal. Thefiltered first IF signal is amplified by the first IF amplifier(Q205) and then applied to the lF system IC (IC200). The IFsystem IC provides a second mixer, second local oscillator,limiting amplifier, quadrature detector and RSSI (ReceivedSignal Strength Indicator). The second mixer mixes the firstIF signal with the 59.395MHz of second local oscillator output(crystal unit X200) and produces the second IF signal of455kHz.The second IF signal is passed through the ceramic filter(CF201 : Wide, CF200 : Narrow) to more remove the adjacentchannel signal. The filtered second IF signal is amplified bythe limiting amplifier and demodulated by the quadrature de-tector with ceramic discriminator (CD200). The demodulatedsignal is routed to the audio circuit.ANTTX/RX : 136~174MHzANTSWRFAMPPAAMPTXAMP1st MIX MCF59.85MHzCF455kHzFM IFSYSTEMAFAMPSP59.395MHz195.85~233.85MHz PLLVCO MICAMPMIC136~174MHzFig. 1 Frequency configurationIC200MIX, DET, IF SW SWQ203 IC606DMUTEIC600 (1/2)AF AMP2nd localOSCX200VOLIC605VC1VC2Q618SSWSWANTSWL111,112L113L215L216BPFD106,107D211,213Q207RFAMPQ2061st MIXQ205IF AMPANTL211L214BPFXF200MCF1st LocalOSC (PLL)CF200CF201AQUA-LIC607HSDOSWQ605(1/2)AM2IC609AF PAINT. SPEXT. SPFig. 2 Receiver sectionCIRCUIT DESCRIPTION