(No.RA016)1-11(6) Attach two spacers to the back side of the orange rubberseal as indicated below.Note:Rubber seal may not attach correctly if the spacer isbrought near by the corner too much.(7) Reinstall the cover and orange rubber seal using the 4screws removed in step 2 and 3.Note:When installing the rubber orange seal on the chassis,ensure that you do not damage the rubber seal and thatthe contact area of the chassis is dust-free.Note:• When the KWD-AE30/ KWD-AE31 is installed, select the"Secure Cryptographic Module" checkbox in the Product In-formation of the KPG-D1/KPG-D1N (programming soft-ware), and then set each parameter.• If the KWD-AE30/ KWD-AE31 connector is not properly in-stalled, the TX/RX indicator will blink red or "No SCM" willappear on the display when the transceiver power is turnedon.• If the Encryption Key data is not written at the Keyloader, orthe Encryption Key data is zeroized, "Key Fail" will appearon the display.• If the KWD-AE30/ KWD-AE31 is installed in other transceiv-ers, the Encryption Key data will be forced to zeroize.2.4 CIRCUIT DESCRIPTION2.4.1 OverviewThe NX-5400 is a 700/800MHz FM & P25 Portable transceiver designed to operate in the frequency range of 763 to 775.99375MHz,793 to 805.99375MHz (700M) and 806 to 825MHz, 851 to 870MHz (800M).The unit consists of a receiver, a transmitter, a phase-locked loop (PLL) frequency synthesizer, a digital control unit, and a power sup-ply circuit.2.4.2 Frequency ConfigurationThe receiver is a double-conversion super-heterodyne using a first intermediate frequency (IF) of 58.05MHz and second IF of2.25MHz. Incoming signals from the antenna are mixed with the local signal from the PLL circuit to produce the first IF of 58.05MHz.This is then mixed with the 55.8MHz second local oscillator output to produce the 2.25MHz second IF.The transmit signal frequency is generated by the PLL VCO, and modulated by the signal from the DSP. It is then amplified and fedto the antenna.Fig.1 Frequency configuration2.4.3 Receiver System2.4.3.1 RF CircuitThe receive signal from antenna switch (D350, D370 and D371) is amplified by a RF amplifier (700MHz band: Q530, 800MHz band:Q550) and passes through the band-pass filter (700MHz band: L536, L530, 800MHz band: L556, L550) to remove unwanted signals.These are controlled with the RF filter switch (IC570 and IC520). The signal is then fed to the 1st mixer (IC500).2.4.3.2 IF CircuitThe first IF signal is passed through a four-pole monolithic crystal filter (XF670) to reject adjacent channel signals. The filtered first IFsignal is amplified by the first IF amplifier (Q670 and Q660) and then applied to the IF system IC (IC600). The IF system IC providesa second mixer, second PLL, AGC and A/D converter.The second mixer mixes the first IF signal with the 55.8MHz of second local oscillator output and produces the second IF signal of2.25MHz.The second IF signal is then be fed into an A/D converter, generates the I and Q data. This data is in the form of SSI (Serial Synchro-nous Interface), and sent to the DSP (IC702).SpacerANT1st MIX 58.05MHz 55.8MHz SP19.2MHzMICANTSWPAAMPRFAMPTXAMPMCF MIXIF CircuitTCXORX PLLVCO2ndTX PLLVCOBasebandCircuitCODECAFAMP700M:763~775.99375MHz(RX/TX)793~805.99375MHz(TX)800M:806~825MHz(TX)851~870MHz(RX/TX)700M:763~775.99375MHz(RX/TX)793~805.99375MHz(TX)800M:806~825MHz(TX)851~870MHz(RX/TX)700M:821.05~834.04375MHz800M:792.95~811.95MHzVCO
