TM 9-6625-1753-14
C1
c. Amplifiers. Common emitter stages Q606 and Q608, with emitter follower Q609, provide power and voltage
d. Normal Trigger Generation.
amplification for the selected trigger. Regulator Q607 controls the voltage on the emitter of Q608 and the collector of Q609.
The output trigger (INT) appears at J9001-25, and is coupled through the main frame to the delayed sweep plug-in unit.
(1) Input.
(a) Before going into a description of how the trigger pulse is generated, assume that the switches described
3-11.5. CH2 OUT Circuit
above are in the following positions:
A sample of the channel 2 signal is available at the CH2 OUT connector, on the front panel. The channel 2 signal, taken from
Q902 (D10) and applied through emitter follower Q603 (A17) is amplified by common emitter stage Q602. This signal,
SOURCE switch S820
INT
adjustable in level by R614 (CH2 output level adj) is available at the CH2 OUT connector. R614 establishes the conduction
COUPLING switch S821
AC
level of gain control stage Q601, and Q601, in turn, regulates the bias on Q602.
SLOPE switch S822
+
NORM-AUTO switch S824
NORM
Section IV. FUNCTIONAL THEORY-DELAYING SWEEP
(b) Further assume that the input signal (output of the dual trace plug-in) is a sine wave. After passing through
the switches, the high-pass filter, and the RC network, the sine-wave input signal is applied to amplifier V8201.
PLUG-IN TYPE 74-13A (X-DEFLECTION)
3-12.
Triggering (Fig. 4-5)
Note. The normal sweep channel and the delayed sweep channel use similar triggering circuits,
therefore, only the functions of the switches and controls for trigger generation in the normal sweep
channel are described.
a. Sources of Trigger Input. Using SOURCE switches S820 (zone A2), you can select any one of the three input signal
sources from which a trigger is to be produced.
(1) INT position. In this position, the input signal, coming from the dual trace plug-in, passes through the SOURCE
switch to COUPLING switch S821.
(2) EXT position. With the SOURCE switch at EXT, the input signal (from an external source connected to the EXT
TRIG connector) passes through the SOURCE switch to the COUPLING switch via PULL EXT 10 switch S823.
(3) LINE position. In this position, the input signal taken from the 6.3 vac heater circuit in the low-voltage power
supply, passes through the SOURCE switch to the COUPLING switch.
b. Methods of Coupling Trigger Input . By setting COUPLING switch S821 to only one of three positions, you select the
type of circuit through which the input signal is to be coupled to the trigger circuit.
(1) AC position. In this position, the input signal passes through high-pass filter C8205, C8203, R8207; NORM-
AUTO switch S824; and RC network R8206, C8202 to SLOPE switch S820. The high-pass filter rejects signals below 80
cycles.
(2) ACF position. With the COUPLING switch set to this position, the input signal is applied to the high-pass filter,
now consisting of C8203, and R8207 and R8204 in parallel. With this new circuit configuration, the high-pass filter rejects
signals below a frequency of 10 kc. After passing through the filter, the input signal continues through the NORM-AUTO
switch to the SLOPE switch via R8206 and C8202. Since C8202 shunts R8206, the high frequency components of the signal
will pass through undisturbed.
c. Polarity Selection of Input Signal. By setting SLOPE switch S822 to either one of two positions, you select the polarity
of the input signal which is used to start the sweep.
(1) "+" position. In this position, the input signal after passing through the RC network (R8206, C8202) continues
through the SLOPE switch to the grid (pin 4) of V8201 (zone B6), which constitutes half of a difference amplifier. The other
half of the difference amplifier V8202 receives a dc bias volt-age at its grid (pin 4), through LEVEL control R8222.
(2) "-" position. In this position, the input signal after passing through the RC network, continues through the SLOPE
switch to the grid of V8202. The dc bias voltage determined by the LEVEL control is now of course applied to the grid of
V8201.
3-6.2
