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Circuit Description— Type M
input signal at the base of Q5324 to a push-pull output
signal between the two collector circuits. Push-pull gain
of the stage is approximately 2.2. Both emitters are long
tailed (through R5325 and R5335) to the +100-volt supply
for greater stability with respect to transistor parameters and
temperatures.
There are two gain controls located in the common-
emitter circuit of the Paraphase Amplifier. One is the VAR.
GAIN control R5236 and the other is GAIN ADJ. control
R5336, a front-panel screwdriver-adjust potentiometer. Both
controls vary the emitter degeneration and thus affect the
gain of the stage. The GAIN ADJ. is adjusted so that the
amount of crt deflection agrees with the setting of the
VOLTS/CM switch when the VAR. GAIN control is set
to the CALIB. position.
The DC BAL. control R5332, a front-panel adjustment, is
used to adjust the dc level of Q5334 so that its emitter
will be at the same voltage as the emitter of Q5324 when
no input signal is applied to the unit. With the emitters
at the same voltage there will be no current through the
VAR. GAIN control. With this configuration an adjustment
of the VAR. GAIN control will not affect the dc level in the
collector circuit of the Paraphase Amplifier stage, and will
therefore not affect the positioning of the beam.
Collector loads R5324 and R5334 develop the output
signal of Q5324 and Q5334. The output signal is push-pull
and is applied to a gate consisting of four diodes— D5345,
D5347, D5346 and D5348.
During multi-trace operation
a positive-going gating pulse is applied to the junction
of R5345 and R5347. The pulse at this junction causes the
diodes to conduct and the push-pull signal passes from the
Input Amplifier, through the diode gate and MODE switch
contacts, to the Output Amplifier.
If the MODE switch is set to either the AC- or DC-NORM.
position, the signal passes through the diode gate and
MODE switch directly to the Output Amplifier to produce
a normal display on the crt. However, when the MODE
switch is set to either the AC- or DC-INV. position, the
switch reverses the signal-grid connections of V5364 and
V5374 and inverts the displayed waveform. When the
MODE switch is set to the OFF position, the Input Ampli
fier is disconnected from the Output Amplifier and no
signals pass through the diode gate.
When all MODE switches are set to OFF, diodes D5360
and D5370 clamp the grids of V5364 and V5374 near
ground, preventing the grids from moving toward —150
volts. In addition, the diodes provide a very convenient
method for checking the dc balance of the Output Ampli
fier. With all MODE switches in the OFF position the grids
are essentially connected together.
Vertical Positioning
The POSITION control, connected between R5341 and
R5343, changes the current through collector load resistors
R5324 and R5334. With the control centered, the current
through each load resistor, under no-signal conditions, is
the same. When the control is moved to either end, a
change of 2 ma per side occurs. This current change re
sults in a positioning voltage range of approximately 300
millivolts at the transistor collectors. The voltage range
corresponds to about ± 1 0 centimeters positioning range
at the crt since direct coupling is employed.
Output Amplifier
The Output Amplifier, which is a common amplifier for
all channels, consists of two stages: Push-Pull Amplifier
V5364/V5374 and Output Cathode Follower V5383.
Push-Pull Amplifier V 5 3 6 4 /V 5 3 7 4 .
The Push-Pull Am
plifier stage provides a total gain of about 5 for signals
and dc-positioning voltages that arrive when the diode gate
for the operating channel is gated ‘‘on” by the switching
pulse from the Ring Counter. The gating pulse itself is not
amplified because it is common mode and cancels out in
the cathode circuit of the stage.
Static current drain in this stage is about 6 ma per side;
1.5 ma is screen current and 4.5 ma is plate current. Static
plate voltage is about 65 volts.
Peaking inductors L5360 and L5370 provide necessary
high-frequency compensation in the grid circuits of the stage.
In the plate circuits variable inductors L5363 and L5373
compensate the stage for high-frequency attenuation caused
by the tube and stray capacity. The m-derived sections of
the variable inductors provide a means for adjusting the
stage for optimum transient response.
A position range network consisting of R5377, R5378 and
R5365 in the cathode circuits of this stage cancel any static
imbalance for centering the traces. With the VERT. POS.
RANGE control, R5378, all traces can be made to coincide
as a group with the vertical system electrical center. Range
of the VERT. POS. RANGE control is about 200 mv at each
grid of V5383, equal to about a 4-centimeter change in
trace position, 8 centimeters push-pull.
Output Cathode Follower V5383.
The Output Cathode
Follower stage operates much the same as the Input Cathode
Follower stage. That is, it provides a high-impedance, low-
capacitance load to the Push-Pull Amplifier stage, and a
low-impedance driving source for the capacitance of the
inter-connecting plug and the input of the main vertical
amplifier in the oscilloscope.
Peaking coils L5384 and L5386 form a series-peaking
circuit with the stray capacitance in their respective circuits.
These peaking circuits are damped by the cathode im
pedance of each side of V5383. Due to the fairly large
cathode resistors (9.1 k) employed, the cathode impedance
is approximately equal to the reciprocal of the transconduc
tance of the tube (1 /G m). By varying the current through
the tube, the H.F. PEAKING control can vary the transcon
ductance, thereby varying the effect of the peaking circuits.
Channel A Signal Output Amplifier
The Channel A Signal Output Amplifier Q5344 and Q5354
is a two-stage transistorized auxiliary amplifier for channel
A only. It provides a dc-coupled signal obtained from
channel A for external triggering purposes, particularly
for use during multi-trace operation in the CHOPPED mode.
3-2
Содержание M 531
Страница 43: ...RIGHT SIDE Parts List Type M http manoman sqhill com...
Страница 45: ...Parts List Type M LEFT SIDE 0 0 0 IP 6 6 http manoman sqhill com...
Страница 56: ..._____________ CHANNEL A __________ SIGNAL OUTPUT AMPLIFIER 1 t y p e m p l u g i n u n i t AI...
Страница 64: ...TYPE M TENT SN 9660 CHANGE TO Q5344A B ELECTRICAL PARTS LIST CORRECTION 151 0232 00 Silicon Dual M15 594 170...