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3. BLOCK DIAGRAM
A N T E N N A
F M
300f]
7 5 r I
G N D
F M
F R O N T - E N D
A M T U N E R
I N D I C A T O R S
S T E R E O
F M I F A M P 8 D E T E C T O R
I C ( P A 3 0 0 t - A )
F M M P X S T E R E O D E M O D U L A T O R
r c ( H A l r 5 6 w )
I C ( H A i l 3 8 )
D I A L
P O I N T E R
P O W E R S U P P L Y
I L L U M I N A T I O N
4. CIRCUIT DESCRIPTIONS
FM Tuner
The FM front end is comprized of a J-FET
(2SK168) single-stage RF amplifier, and NPN
transistor mixer, and an NPN transistor modified
Clapp local oscillator.
The IF stage consists of. 2 dual-element ceramic
filters, a single transistor amplifier element, and
IF system IC (PA3001-A) which incorporates the
IF limiter amplifier, FM detector, ffid the FM
muting circuit.
FM Multiplex Stereo Decoder
The stereo decoder stage employs an FM MPX
IC (HA1L56W-P), while the subcarrier signals
(frequencies above 19kHz) are removed by an
- 18dB/oct. active filter consisting of a PNP tran-
sistor. This active filter also serves as an amplifier
for frequencies within its passband, and eliminates
crosstalk.
AM Tuner
The AM tuner is two wave-band tuner $rith LW
(150kHz-350kHz) and MW (525kHz-1605kH2).
This employs a 2-ganged tuning capacitor, a single
element ceramic filter, and an IC (HA1138)
consisting of an RF amplifier, mixer, 2-stage IF
amplifier, detector and AGC circuit.
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