Circuit Description - Yaesu FT-301 Instruction Manual

CIRCUIT DESCRIPTION
The block diagram and the circuit description that
follows, will provide you with a detailed under-
standing of this transceiver design. Computer type
plug-in modular construction is used throughout
the transceiver for RF isolation, service and
alignment purposes.
The transceiver consists of a premix type single
conversion system with a 9 MHz IF for all modes
of operation.
RECEIVER
The RF input signal from the antenna is fed to pin
4 of the RF unit (PB-1443) through RL-1 (relay),
trap T 1401 /C 1413 in the trimmer unit and T 1, the
permiability tuned RF input coil.
Figure 13
Figure 14
RF UNIT (PB-1433)
The incoming signal is amplified by the RF ampli-
fier Q
102 ,
3SK40M PET, and then fed to the gate
of the mixer Q
103 ,
3SK40M, where the input RF
signal is heterodyned with a local signal delivered
from pre-mix circuit (PB-1439), producing an IF
signal of 9 MHz at pin 11, through Tl 02.
The input and output of the RF amplifier are per-
miability tuned circuits which provide high sensi-
tivity with excellent rejection of unwanted out-of-
band signals.
FILTER UNIT (PB-1435)
The IF signal received at pin 2
is passed through
the monolithic filter XF -301 which has a
±
10 kHz
RF Unit (PB-1433C)
Filter Unit (PB-1435E)
- 15-