Transmitter Circuit - HYT TM-610 Service Manual

TM-610 Service Manual
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 second local oscillator signal (50.4MHz) to become a 450KHz second IF signal. The
second IF signal is then fed through a ceramic filter (N: CF202; W: CF203) to eliminate unwanted signals.
The resulting signal then is detected by IC102 and output from Pin 9 as audio signals.
2.4 Audio Amplifier
The audio signal obtained from IC102 is amplified and filtered by IC402 before being amplified by IC401
(the received signalling is separated and input into CPU for decoding). The processed signalling passes
through Q406 (AF MUTE) and is amplified by IC405. The amplified signal is fed to K301 controlling the
volume and Q511 controlling SP MUTE on the front panel before entering audio amplifier (IC511). The
output audio signal drives the speaker.
2.5 Squelch Open
Part of the audio signals output from IC102 passes through IC102 Pin8 and is amplified by IC102 again,
then is filtered and rectified to produce an SQL level. The SQL level is compared with the existing
reference level in CPU (IC502) to generate a level to control AF MUTE and SP MUTE, which determines
whether to output sounds from the speaker by controlling Q406 and Q511.

3. Transmitter Circuit

The transmitter circuit is composed of the MIC circuit, modulation circuit, RF driver, final-stage power
amplification circuit and APC circuit.
Figure 2 Transmitter Circuit
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