Circuit Description; Frequency Configuration; Receiver Circuit; High Frequency Bandpass Amplifier Circuit - HYT TM-610 Service Manual

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Circuit Description

1. Frequency Configuration

The receiver utilizes double conversion superheterodyne. The first IF is 49.95MHz and the second is 450KHz. The first
local oscillator signal is supplied by the PLL circuit; and the second (50.4MHz) is generated from the frequency tripling of
TCXO (16.8MHz). The PLL circuit generates the frequencies required for transmission. (See figure 1).
Frequency Range VHF: 136MHz - 174MHz
UHF: 400MHz - 470MHz

2. Receiver Circuit

The receiver circuit is shown as figure 1.

2.1 High Frequency Bandpass Amplifier Circuit

It consists of BPF, RF amplifier (Q111) and BPF (D110 and D111). The range of bandpass frequency is the frequency
range of the radio itself. The signal is filtered by the BPF to eliminate unwanted signals before going to the first mixer.
2.2 First Mixer
The signal from BPF is mixed with the first local oscillator signal from PLL circuit at the first mixer (D112) to become a
49.95MHz first IF signal. The first IF signal is then fed through the crystal filter (IF200) to further remove spurious signals.
2.3 IF Amplifier
The first IF signal is amplified by Q113 and then enters IC102 (TA31136FN), where the signal is mixed again with the
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450MHz - 500MHz
470MHz - 520MHz 350MHz - 400MHz
440MHz - 470MHz 480MHz - 526MHz
330MHz - 350MHz
Figure 1 Receiver Circuit
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TM-610 Service Manual
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CTS67.0HZ DI423
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