Fig.5
L-7t-L
Low Pass Filter.
(2)1mpedance Detector Circuit
The impedance detector circuit detects the impedance
of
the matehing circuit input
terminal and the output signals are sent to the CDJ-1143 control
CPU.,
The circuit made up of diades CD401 and CD402, IC403 and peripheral parts mea-
sures impedance.
The valtage at the input terminal
is
detected by capacitors
C401
and C402 and diode
. CD401. On the other hand, the current at the inputterminal
is
detected by the current
transformer
T1
and diode CD402.
The detected valtage and current are compared by IC403 comparator.
The LOADsignal changes to Low Ievei when the impedance at the inputterminal is
over 50 ohms, and the signal changes to High Ievei when it is below 50 ohms.
The circuit made up of IC401, IC402 and IC403 and peripheral parts detects the
phase of the impedance.
After the valtage and current at the input terminal are wave-shaped by
IC401
, they are
applied to IC402 where the D-type flip-flop detects the phase of the valtage and cur-
rent.
When the phase of the current is advanced
tothat
of the voltage, the TUNEsignal
is
High Ievei, and it changes to Low Ievei when the phase is behind the valtage phase.
The circuit made up of diades CD421, CD441, IC404, IC405 and peripheral circuit
parts detects the VSWR value of the input terminal.
Diode CD421 detects the torward valtage (Vf) and diode CD441 detects reflected
valtage (Vr). Vf and
Vr
are compared by IC404 comparator and three output signals,
SWR1.1 , SWR1.5 and SWR2.0 are obtained. The Low Ievei of SWR1.1 signal means
~
that the VSWR value of the input terminal
is
below 1
.1
.
(3)Relay Drive Circuit
The circuit made up of
IC301
to IC304 drives relays.
Each
IC
receives serial input data and sends out
an
8-bit latched parallel signal. The
CDJ-1143 control CPU sends 32-bit relay data to the ICs
in
serial signals.
13
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