HARRIS CORPORATION TR-391-A2 Manuel D’Utilisation
KME 900 Instruction Draft
1, Receiver Circuit
The FM dual-conversion super heterodyne receiver is designed for operation in the 935-941MHz frequency
range.
The Receiver has intermediate frequencies (IF) of 82.2MHz and 455KHz.
Adjacent channel selectivity is obtained by using two band pass filters, a 82.2MHz crystal filter and a 455KHz
ceramic filter.
The FM-detector is Quadrature discriminator.
The FM dual-conversion super heterodyne receiver is designed for operation in the 935-941MHz frequency
range.
The Receiver has intermediate frequencies (IF) of 82.2MHz and 455KHz.
Adjacent channel selectivity is obtained by using two band pass filters, a 82.2MHz crystal filter and a 455KHz
ceramic filter.
The FM-detector is Quadrature discriminator.
1-1 Receiver Front-end
A RF signal from antenna is coupled though the low pass filters, antenna switch and band pass filter to the
input of low noise amplifier TR201. The output of TR201 is coupled through band pass filter to input of 1’st
Mixer TR203.
Front End selectivity is provided by these band pass filter.
A RF signal from antenna is coupled though the low pass filters, antenna switch and band pass filter to the
input of low noise amplifier TR201. The output of TR201 is coupled through band pass filter to input of 1’st
Mixer TR203.
Front End selectivity is provided by these band pass filter.
1-2 1’st Mixer
The 1’st Mixer is a Transistor-Mixer (TR203), that converts a RF signal the 935-941MHz range to 82.2MHz
1’st IF frequency.
In the mixer stage, A RF signal from the Front-end RF filter is applied to the input of the Transistor-Mixer.
The 1’st Mixer is a Transistor-Mixer (TR203), that converts a RF signal the 935-941MHz range to 82.2MHz
1’st IF frequency.
In the mixer stage, A RF signal from the Front-end RF filter is applied to the input of the Transistor-Mixer.
1-3 1’st IF
The 82.2MHz 1’st IF output signal is coupled from the output of T201 through IF amplifier TR204 and Crystal
filter FL201 to IF-amplifier TR205.
The highly-selective crystal filters FL201-1 and FL 201-2 provide the first portion of the receiver IF
selectivity. The out put of the filters is coupled through the impedance-matching net work T204, C246 and
R224 to 1’st IF amplifier TR205.
The 82.2MHz 1’st IF output signal is coupled from the output of T201 through IF amplifier TR204 and Crystal
filter FL201 to IF-amplifier TR205.
The highly-selective crystal filters FL201-1 and FL 201-2 provide the first portion of the receiver IF
selectivity. The out put of the filters is coupled through the impedance-matching net work T204, C246 and
R224 to 1’st IF amplifier TR205.
1-4 2’nd Mixer, 2’nd IF filter,2’nd IF amplifier and FM detector
IC201 is an one-chip IC for FM communication system. It includes 2’nd Mixer, 2’nd IF amplifier and FM
detector.
The 2’nd Mixer is a Balanced Mixer, that converts a 1’st IF signal 82.2MHz range to 455KHz 2’nd IF
frequency. The 2’nd IF signal is applied to Ceramic Filter FL203, which provides the 455KHz selectivity.
IC201 is an one-chip IC for FM communication system. It includes 2’nd Mixer, 2’nd IF amplifier and FM
detector.
The 2’nd Mixer is a Balanced Mixer, that converts a 1’st IF signal 82.2MHz range to 455KHz 2’nd IF
frequency. The 2’nd IF signal is applied to Ceramic Filter FL203, which provides the 455KHz selectivity.
The output of the 2’nd IF filter is applied to 2’nd IF amplifier in IC201.
The 2’nd IF signal is then amplified, filtered and limited. Discriminator (DSC201) shifts the 2’nd IF signal by
90deg and applies it to the internal FM detector.
The FM detector compares the shifted IF signal to the internal IF signal to recover the audio modulation. The
audio output of IC201 is applied to audio amplifier buffer IC205-2.
The audio output of IC205-2 is then applied to the SYSTEM CONTROL UNIT.
The 2’nd IF signal is then amplified, filtered and limited. Discriminator (DSC201) shifts the 2’nd IF signal by
90deg and applies it to the internal FM detector.
The FM detector compares the shifted IF signal to the internal IF signal to recover the audio modulation. The
audio output of IC201 is applied to audio amplifier buffer IC205-2.
The audio output of IC205-2 is then applied to the SYSTEM CONTROL UNIT.
2, Transmitter Circuit
The Transmitter Circuit consists of one Class-A Amplifier TR101, Pre-Driver IC101, PA Module IC102, RF
Amplifier TR102, Automatic Power Control Circuit (TR105- TR107), Antenna Switch (CD103, CD105-
CD107 and CD109), Low Pass Filter (Micro Strip Line and C146-C153, C181 and C183).
The Transmitter Circuit consists of one Class-A Amplifier TR101, Pre-Driver IC101, PA Module IC102, RF
Amplifier TR102, Automatic Power Control Circuit (TR105- TR107), Antenna Switch (CD103, CD105-
CD107 and CD109), Low Pass Filter (Micro Strip Line and C146-C153, C181 and C183).
2-1 Class-A Amplifier
The 896-902MHz and 935-941MHz RF input from Synthesizer output of TR316 is applied to the band pass
filter FL301 through an attenuator pad R301-R303. RF input level is about +3dBm, that is amplified to
+10dBm by TR101. This is controlled by TXENB+.
The 896-902MHz and 935-941MHz RF input from Synthesizer output of TR316 is applied to the band pass
filter FL301 through an attenuator pad R301-R303. RF input level is about +3dBm, that is amplified to
+10dBm by TR101. This is controlled by TXENB+.