Table of Contents
Advertisement
6-1. EXPLANATION OF CIRCUITRY
6-1-1.
Oscilloscope Portion
Signals input via the BNC pass through the AC-DC converter
circuit (which is composed of relays), GND select circuit,
attenuator circuit, and source follower, and are then input
into the preamp. This preamp consists of a ''feed forward"
control configuration in which high-frequency components
are amplified by transistors and low-frequency components
are amplified by op amps. The resulting output is split into
two signal paths for distribution to the final amp and the
trigger sweep
circuit. The final amp, which consists of
differential amplification circuits, directs the resulting out-
put into the Y-deflection plate of the CRT.
Signals entering the trigger sweep circuit are passed to a
clamping circuit and Schmitt circuit for waveform shaping
and divided into two paths. One is input as a clock signal
- for the sweep gate flip-flop, and the other is sent into an
"'auto' circuit. This auto circuit detects the presence or ab-
sence of an input signal and supplies the SET signal for the
triggered sweep and the auto free-run sweep.
The trigger sweep circuit consists of components which in-
clude a sweep gate flip-flop, constant-current circuit, com-
parator, and hold-off circuit; it generates a sawtooth sweep
voltage. The constant-current circuit determines the incli-
nation of the sawtooth wave, that is, the sweep interval;
and the comparator determines the amplitude of the wave,
that is, the length of the beam trace. The hold-off circuit
determines the hold-off interval. The output of this hold-off
circuit is sent into the SET input of the sweep gate flip-flop
as an "'end-of-sweep"' signal.
The output of the trigger sweep circuit is input into the fi-
nal amp which is composed of differential amplification cir-
cuits.
The
resulting
amp
output
is directed
into
the
X-deflection plate of the CRT.
6-1-2.
Bandscope Portion
The attentuated sawtooth waveform is input as a bias vol-
tage into the variable capacitor in the LC oscillation circuit
to change the oscillation frequency by a scan signal width.
This controlled oscillation frequency signal is mixed with the
previously-mentioned input signal (IF signal). Then, the mixer
output is amplified by a log amp, rectified, and then input
into the vertical amplifier.
6-1-3.
Monitor Portion
RF signals input via the transceiver are passed through
signal-pickup resistors and condensers and into the RF at-
tenuator. Here, the signals are further attenuated by con-
densers and divided into two paths. One is input into the
Y-deflection
plate of the CRT, and the other is passed
through a detector circuit and input into the trigger sweep
Circuit.
The RF input is equipped with a surge absorber.
6-1-4.
X-TUNE Portion
MARK
signals and SPACE
signals input from the RTTY
demodulator are condenser-coupled, and are then input into
an amplifier which is composed of op amps. The unit is con-
figured with analog switches in such a way that the result-
ing output is directed to the final amp only during operation
in the X-TUNE mode.
6-1-5.
TWO-TONE Portion
This portion is constructed using a Wien Bridge oscillator
circuit and is temperature compensated. It thereby produces
high-stability signals.
6-1-6.
Power Supply Circuitry
The stabilized power source outputs voltages of +5 V,
+10 V, and +140 V. The circuitry, constructed entirely of
op amps and control transistors, creates the + 140 V out-
put from an unregulated 170 V, the + 10 V from an unregu-
lated 13 V, and the. +5 V from the regulated + 10 V. For
the +10 V and +140 V outputs, bleeder resistors are con-
nected between the emitter and collector of the transistors
to reduce the power consumption of the control transistors.
The high voltage circuit consists of components which in-
clude a transformer, a high-voltage block using a voltage
doubler rectifier connection, oscillating transistors, and con-
trol op amps; it therefore provides extremely high stability.
In this case, it produces an output of 1.8 V.
6-2. UNIT STRUCTURE
The main units making up the SM-230 include the vertical
power supply unit, the horizontal unit, and the panel unit.
6-2-1.
Vertical Power Supply Unit (X73-1870-00)
This unit includes the AC-DC converter circuit used by the
oscilloscope, the GND selector circuit, the attenuator cir-
cuit, the vertical preamp, and the power supply circuit.
6-2-2.
Horizontal Unit (X74-1510-00)
This unit includes the trigger sweep circuit, the vertical fi-
nal amp, the horizontal final amp, the X-TUNE amp, the band
scope oscillator circuit, the log amp, and the TWO-TONE
oscillator circuit.
6-2-3.
Panel Unit (X69-1160-00}
This is the unit to which the panel switches are directly at-
tached,
and it transmits
information
from the switches
directly to the vertical power supply unit and horizontal unit.
lt also includes the CAL circuit.
6-2-4.
Monitor Input Unit (X69-1160-00)
This unit includes the RF pickup resistors, condenser, de-
tector, and surge absorber.
15
Advertisement
Table of Contents
