Kenwood TK-6110 Service Manual

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Contents

13TK-6110CIRCUIT DESCRIPTIONFig. 1 Frequency configurationFig. 2 Receiver section1. OverviewThe KENWOOD model TK-6110 is a VHF/FM transceiverdesigned to operate in the frequency range of 29.7 to37MHz (K), 35.0 to 50.0MHz (K2), the unit consists of a re-ceiver, a transmitter, a phase-locked loop (PLL) frequencysynthesizer, power supply circuits, a control unit.2. Circuit Configuration by FrequencyThe receiver is a double-conversion superheterodynewith a first intermediate frequency (IF) of 128.55MHz and asecond IF of 455kHz. Incoming a signals from the antennaare mixed with the local signal from the PLL1 to produce thefirst IF of 128.55MHz.This is then mixed with the 129.005MHz seconds localoscillator output to produce the 455kHz second IF. This isdetected to give the demodulated signal.The transmit signal is modulated PLL2-VCO2 (129.005MHz) from the microphone. The transmit signal frequencyis down-conversion with PLL2 and PLL1. It is then amplifiedand sent to the antenna.3. Receiver System3-1. Front-End RF AmplifierAn incoming signal from the antenna is applied to a band-pass filter (L202) after going through a low-pass filter and anantenna switch (K1). The signal is then amplified by the RFamplifier (Q201) and again filtered by another band-pass fil-ter (L203, L206 and L207).3-2. First MixerThe signal from the band-pass filter is heterodyned withthe first local oscillator signal from the PLL frequency syn-thesizer circuit at the first mixer (IC201) to become a128.55MHz first intermediate frequency (IF) signal.The first IF signal is fed through two monolithic crystalfilters (XF201) to further remove spurious signals.3-3. IF AmplifierThe first IF signal is amplified by Q202 and Q205, andthen enters IC202 (FM processing IC). The signal is hetero-dyned again with a second local oscillator signal(129.005MHz) with in IC202 to become a 455kHz second IFsignal. The second IF signal is fed through a 455kHz ce-ramic filter, CF201 and CF202 to further eliminate unwantedsignals before it is amplified and FM detected in IC202.ANTTX/RX29.7~37.0MHz : K35.0~50.0MHz : K229.7~37.0MHz : K35.0~50.0MHz : K2LPF ANTSWPAAMPTXAMP1st MIXTX MIXMCF128.55MHzCF455kHzFM IFSYSTEMAFAMP SP129.005MHz129.005MHzPLL2VCO2PLL1VCO1MICAMP MIC158.25~165.55MHz : K163.55~178.55MHz : K2158.705~166.005MHz : K164.005~179.005MHz : K2T/RSWBPFQ201RF AMP BPF BPF LPFIC2011st MIX D502MCF128.55MHzQ205IF AMPQ202IF AMPIC202FM IF SYSTEMCF201,202455kHz129.005MHzXF201Item RatingNominal center frequency 128.55MHzPass bandwidth ± 7.5kHz or more at 3dBAttenuation bandwidth ± 35kHz or less at 40dBRipple 1.0dB or lessInsertion loss 5dB or lessGuaranteed attenuation 70dB or more at fo± 910kHzTerminating impedance 1000ΩTable 1 Crystal filter (L71-0560-05)(TX-RX unit XF201)