HYT TC-446, Service Manual

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TC- 446 Service Manual
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Circuit Description
1. Frequency Configuration
The receiver utilizes double conversion superheterodyne. The first IF is 21.4MHz and the second
is 455KHz. The first local oscillator signal is supplied from PLL circuit. Frequency needed in the
transmitter is supplied from PLL circuit. Figure 1 shows the frequency configuration.
Frequency Range: 446.00625 MHz— 446.09375MHz
Figure 1 frequency configuration
2. Receiver
The receiver utilizes double conversion superheterodyne.
1) Front-end RF Amplifier
The input signal from antenna is amplified in RF amplifier (Q27) after passing through
the receive/transmit switch circuit and a 3-stage LC band pass f ilter. The amplified
signals are filtered by a band pass filter (a 3-stage LC BPF) to eliminate unwanted
signals before they goes to the first frequency mixer.
Figure 2 receiver section configuration