HYT TM-800K, Service Manual

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TM-800K Service Manual
16
Circuit Description
Frequency Configuration
The receiver utilizes double conversion superheterodyne. The first IF is 49.95MHz (VHF) / 73.05MHz
(UHF) and the second is 450 KHz. The first local oscillator signal is supplied by PLL circuit. The second
local oscillator signal (73.5MHz) of UHF model is generated from TCXO (73.5MHz); the second local
oscillator signal (50.4MHz) of VHF model is generated from the frequency tripling of TCXO (16.8MHz).
The PLL circuit also generates the frequencies needed in the transmitter ( See Fig.2 ).
Frequency Range: 136 MHz - 174MHz
U1: 400 MHz - 470MHz U2: 450 MHz - 512MHz
U3: 480 MHz - 526MHz U4: 440 MHz - 490MHz
U5: 350 MHz - 400MHz U7: 450 MHz - 520MHz
Receiver Circuit
The receiver section configuration is shown as Fig. 1.
Figure 1-a UHF Receiver Section Configuration
Figure 1-b VHF Receiver Section Configuration