Model 122A/AR Section IV
Paragraphs 4-1 to 4-5
SECTION IV
PRINCIPLES OF OPERATION
4-1. OVER-All DESCRIPTION. an ac range, the signal goes through a capacitor. If
the switch is on a dc range, the signal goes directly
4-2. GENERAL CONTENT.
to the attenuator. The attenuator has three frequency-
4-3. This section contains adescription of the princi- compensated networks: a straight-through range, an
ples of operation of the Model 122A/AR Oscilloscope. OFF position (where the input grid is shorted), and a
The oscilloscope is comprised of five major functional CAL position. In the CAL position the calibrator output
circuit groups: the vertical amplifiers, the sweep is connected -to the vertical amplifier input and plate
generator, the horizontal amplifier, the low-voltage voltage is connected to the calibrator. The calibrator
power supply, and the high-voltage power supply is a neon-lamp relaxation oscillator. The vertical
(see Figure 4-1). amplifier is composed of three dc-coupled differential
stages in cascade. Common to the two input channel
4-4. VERTICAL AMPLIFICATION CHANNELS.
amplifiers are a switching amplifier, a switching multi-
4-5. Since the two vertical channels are similar, vibrator and a trigger amplifier. The input stage of
only one description will be given. The vertical each channel has the BAL adjustment between the
amplifier receives the input signal, amplifies it, and cathodes. The VERT SENSITIVITY VERNIER and the
drives the vertical deflection plates. It provides at- GAIN adjustment are between the plates of the input
tenuation of the input signal, determines the vertical amplifier stage. The second and output stages ineach
position of the spot on the screen, and supplies a sig- channel have plate-to-grid neutralization. The VERTI-
nal for internal synchronization. The signal comes CAL POSITION control is connected between the cathodes
into the inwt terminals andis fed to the ac-dc section of the second stage. The output stage is controlled by
the VERT SENSITIVITY switch. If the switch is on the switchingamplifierwhoseplatesfurnish thecathode
V I
I
I
> I SIGNAL
CHAN B I
e+'
INPUT I
I Y-AXIS DEFLECTION
e+
TRIG
(DIFFERENTIAL)
IINT+I
BLANKING
Lq+q SWITCH
HORIZ TO C \
8
SYNC
INPUT
V
> I HORlZ
- -
(OTHERS)
115v/23ov
HIGH
60 Hz HEATERS SUPPLY VOLTAGE ' HIGH VOLTAGE
LOW -
lPH= VOLTAGE 6.3V POWER FOCUS VOLTAGE
POWER INTENSITY VOLTAGE
SUPPLY
E+ 8 BIAS SUPPLY ASTIG VOLTAGE
12ZA-c-4
Figure 4- 1. Over-all Block Diagram
00081-3 4- 1 |
ACEC
