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3-2
• RF UNIT (Receive circuits)
ATT
PRE
AMP
Q1211
Q1212/Q1213
LPF
LPF A
HPF A
RF
HPF
MUTE
BPF
BPF
BPF
BPF
BPF
BPF
BPF
BPF
LPF
BPF
BPF
BPF
BPF
0.03-1.59 MHz
1.60-74.80 MHz
To the TX AMP
D1081~D1083
D1001
50.00-54.00 MHz
22.00-29.99 MHz
30.00-49.99 MHz
54.01-69.99 MHz
70.00-74.80 MHz
15.00-21.99 MHz
2.00-2.99 MHz
4.50-6.49 MHz
10.00-14.99 MHz
3.00-4.49 MHz
1.60-1.99 MHz
8.00-9.99 MHz
6.50-7.99 MHz
1.60-30.00 MHz
RF UNIT
3-2 RF UNIT
The RF UNIT is composed of the receive and transmit RF circuits.
The received signal from the PA UNIT is passed to the MAIN
UNIT through the attenuator, fi lter, and preamp.
The transmit signal from the MAIN UNIT is passed to the PA
UNIT through the fi lter, ALC circuit, and YGR AMP.
(1) RECEIVE SIGNAL PROCESSING
The received signal from the PA UNIT is passed through
the RX mute switch (D1001), passes through or bypasses
the attenuator (D1081 ~ D1083) according to the Attenuator
function setting, and is then applied to the fi lter circuit. The
attenuator (D1081 ~ D1083) is controlled to change the at-
tenuation level to between 0 dB (bypass) and 20 dB.
The fi lter circuit is composed of 15 fi lters. The received signal
is passed through the fi lter that is selected according to the
receive frequency.
The received signals of 1.6 MHz and below are passed
through only "LPF (A)." The received signals of 1.6 MHz and
above are passed through "HPF (A)," which is designed to
prevent interference by strong MF band broadcast stations.
This HPF is designed to obtain more than 20 dB of isolation
for 1.6 MHz and lower frequencies. The received signals of
1.6 MHz and above are also passed through one of the BPFs,
according to the selected operating band.
The fi ltered signal is then applied to the preamp circuit. The
received signal may be amplifi ed by P.AMP1 (normal gain) or
P.AMP2 (higher gain), or bypass both, according to the Pre-
amp function setting. The received signal from the preamp
circuit is then applied to the MAIN UNIT.
TX signal
RX signal