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The DC component
of the detected
IF signal is used as a AGC voltage to control emitter
current of RF and IF amplifier through the resistor R154 and R155. A part of the DC component
is also applied to the signal strength indication amplifier incorporated in the IC. The output
appears at pin (4 and is level adjusted by R152, indicated on the signal strength meter M004.
2.1
Suggestions for AM Tuner Trouble Shooting
3. FM TUNER
The IF amplifier unit consists of five stages of IF amplifier and one stage of AGC amplifier.
Three pieces of dual elements ceramic filters are also used to obtain high selectivity, four stages
of symmetrical
diode limiters are also employed for the best limiting characteristics, improved
capture ratio and good AM suppression.
3.1
Audio Muting and Stereo Mode Auto-Selecting Circuit
3
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