1. Overview

The VX-3200Vis a VHF/FM mobile transceiver designed to operate in the frequency range of 148 to 174MHz(C Band), or 134 to 160MHz(A Band).

2. Circuit Configuration by Frequency

The receiver is a double-conversion superheterodyne with a first intermediate frequency (IF) of 44.25MHz and a second IF of 450kHz. Incoming signals from the antenna are

mixed with the local signal from PLL to produce the first IF of 44.25MHz.

This is then mixed with the 44.25MHz second local oscil-

lator (using the 14.6MHz TCXO) output to produce the 450kHz second IF. This is detected to give the demodulated signal.

The transmit signal frequency is generated by PLL VCO, and modulated by the signal from the microphone. It is then amplified and sent to the antenna.

3. Receive Signal Path

Incoming RF signals from the antenna connector are delivered to the RF Unit. RF signals pass through a low-pass

filter (LPF) antenna switching network consisting of coils L1001, L1003, and L1005, capacitors C1004, C1008, C1009, C1135, and C1011, and antenna switching diodes D1005, D1007, and D1031, for delivery to the receiver front end.

Signals within the frequency range of the transceiver are then passed through a varactor-tuned bandpass filter con-

sisting of L1009, and L1014 before RF amplification by Q1011 (2SC3356).

The amplified RF is then band-pass filtered again by var-

actor-tuned resonators L1022, and L1027 to ensure pure in-band input to 1st mixer Q1038 (SPM5001).

Buffered output from the VCO Unit is amplified by Q1021 (2SC5107) and low-pass filtered by L1030 / L1031 and

C1178 / C1072 / C1180 / C1129 / C1182, to provide a pure

1st local signal between 192.25 and 218.25MHz(C Band), 178.25 and 204.25MHz(A Band) to the 1st mixer.

The 44.25MHz 1st mixer product then passes through dual

monolithic crystal filters XF1001, and is amplified by Q1029 (2SC4215Y) and delivered to the input of the FM IF subsystem IC Q1028 (TA31136FN).

This IC contains the 2nd mixer, 2nd local oscillator, limiter amplifier, FM detector, noise amplifier, and squelch gates.

The 2nd LO in the IF-IC is produced from crystal X1001 (14.600MHz) and the 1st IF is converted to 450kHz by the 2nd mixer and stripped of unwanted components by ceramic filter CF1001 or CF1002. After passing through a

limiter amplifier, the signal is demodulated by the FM detector CD1001 (CDBC450CX24).

Circuit Description

Detected audio from Q1029 is applied to Q2016 (AK2345)

and audio low-pass filter. After volume adjustment by Q2014 (M62364FP), the audio signal is amplified by the AF power amplifier Q1509 (TDA2003H) and passed to

speaker jack.

4. Transmit Signal Path

Voice audio from the microphone is delivered via the Mic

(Jack) Unit to the PANEL Unit, after passing through amplifier Q2022 (NJM2902V), Mic gain-volume Q2014 (M62364FP) pre-emphasis Q2015 (NJM2902V), and lim-

iter (IDC instantaneous deviation control), is adjusted for optimum deviation level and delivered to the next stage.

Voice input from the microphone CTCSS, and DCS audio are modulated by the VCO, and the reference frequency oscillator of the synthesizer.

Synthesizer output, after passing through diode switch D1022 (1SS321), is amplified by driver Q1025 (2SC5415E) / Q1026 (2SC5107-O) and power module Q1039 (RA60H1317M) to obtain full RF output. The RF

energy then passes through antenna switch D1005 / D1007

/D1031 and a low-pass filter circuit and finally to the an-

tenna connector.

RF output power from the final amplifier is sampled by CM coupler and is rectified by D1011, D1012 (HSM88AS

x 2). The resulting DC is fed through Automatic Power Controller Q1003 (NJM2902V), to transmitter RF ampli-

fier and thus the power output.

Generation of spurious products by the transmitter is minimized by the fundamental carrier frequency being equal to the final transmitting frequency, modulated directly in the transmit VCO. Additional harmonic suppression is provided by a low-pass filter consisting of L1001, L1003,

L1004, L1013, C1004, C1008, C1009, C1135, C1011, C1014, C1209, and C1205, resulting in more than 60dB of harmonic suppression prior to delivery to the RF energy to the antenna.

5. PLL Frequency Synthesizer

PLL frequency synthesizer consists of the VCO Q1013 (2SK508-K52:RX) and Q1015 (2SC5107-O:TX), VCO buff-

ers Q1018 (2SC5107-O),Q1020 (2SC5107-O),Q1021

(2SC5107-O), PLL subsystem IC Q1023 (MB15A02PFV1) and 14.6 MHz reference TCXO X1001.

The frequency stability is +/- 2.5 ppm within temperature range of -30 to +60 degree. The output of the 14.6 MHz reference is applied to pin 1 of the PLL IC.

While receiving, VCO Q1013 oscillates between 192.25 and 218.25 MHz (C Band), 178.25 and 204.25 MHz (A Band) according to the transceiver version and the programmed receiving frequency. The VCO generates 192.25 to 218.25MHz (C Band), 178.25 to 204.25MHz (A Band)

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