Yaesu FL-110, Instruction Manual

Page: 9 / 16

CIRCUIT DESCRIPTION
The FL -110 consists of four major parts -- COUPLING UNIT,
CONTROL UNIT, BOOSTER UNIT and LPF unit. On receive
mode, a received signal is fed through J 1, RL 1 and J2 to the
transceiver antenna terminal.
On transmit, the output signal from the transceiver antenna
passes through the CM coupler TlOl in the coupler unit PB-1680
where the RF voltage is detected and applied to the control unit
PB-1681 in order to activate the relay RLl.
A forwarding wave is detected by the voltage doubler rectifier
DlOl and Dl03, lS-1007 and a reflected wave is detected by Dl02
and Dl04, lS-1007. The rectified DC voltages are applied to a
comparator Q204, µPC -271C which controls relay driver,
Q201, 2SC372Y and Q202, 2SC735Y. With high reflected wave,
such as VSWR 1: 3, the output of Q204 is low and the relay driver
circuit does not function.
A part of the DC voltage obtained from the forwarding wave is
applied to the AFP circuit in order to operate RL201 to disconnect
the activating voltage for RLl thus protecting the PA transistors
from damage due to overdrive. The relay hold time is set to either
FAST or SLOW by adding C201 for a longer discharge time.
When RLl is activated, the bias voltage is applied to the PA transistors
and the amplifier starts to operate.
The driving power is fed through the equalizer circuit consisting of
Rl210, Rl211, Cl201, Cl202, Rl201, Rl202 and Ll201 to the input
transformer T 1201 to be amplified by Ql201 and Ql202, SRF-1427 which
works as a wide -band linear amplifier in a push-pull configuration.
The Negative Feedback circuit consisting of Rl206, Ll204, Rl204
and Ll203 improves the stability and the linearity of the PA stage.
The 13. 5 Volt DC voltage is regulated to 0. 65 volts by a regulator
Ql203, 2SD235 to be used as bias for Ql201 and Ql202. Ql203 is
controlled by the voltage generated by Dl201 and Dl202, lODlO which
varies in accordance with the temperature of the final transistor in
order to protect the final transistor.
The amplified output is fed through the Low-Pass Filter Unit, PB-1577
which reduces the harmonic radiation, and then passes through relay
RLl to the antenna.
A portion of the output power is coupled through T301 to the AFP
circuit.
The DC voltage obtained by rectifying the forwarding power with
D302 and D304, lS-1007 is fed to Q203, CWOlB which controls
RL201 to open RLl when the output power exceeds preset value
set by VR301.
The DC voltage obtained by a reflected power caused by high VSWR
( more than 1: 3) also controls Q203 to open RL 1.
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