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TYPE 1391-9 PULSE, SWEEP, ANQ TIME-DELAY GENERATOR
developed. The conducting output tube produces a current of
ditional binding post normally grounded to the panel through a
150 ma. Screen voltage on this stage is varied to control pulse
shorting link. Under these conditions the output pulses contain
amplitude.
an a-c component negative with respect to ground. If the shorting
The output system i s balanced, and the push-pull pulses
link is removed, the d-c component of an external voltage (from
appear a t coaxial connectors and parallel binding posts. The
any low-voltage laboratory supply or battery able to furnish 150
low-potential side of the load resistors i s connected to an ad-
ma) can be varied by about +25 volts.
Section
2
OPERATING PROCEDURE
2.1
GENERAL. The Type 1391-B Pulse, Sweep, and Time-
Delay Generator can, for instructional purposes, be considered
four separate instruments. If a thorough familiarity with all con-
trols i s neither desired or needed, study merely those paragraphs
that apply to the circuits being used, a s listed below:
2.2
Auxiliary Equipment
2.3
Initial Control Settings
2.4
Synchronization
2.5
Delay Circuit
2.5.1
Normal Use
2.5.2
Time Selection
2.6
Sweep Circuit and Pulse Duration-Delay System
2.7
Pulse-Generatingcircuit
2.8
Use of the PULSE START STOP TRIGGERS
switch
2.2
AUXILIARY EQUIPMENT. A few auxiliary instruments
are usually needed a s components of the external system.
First, a source of a timing waveform is needed to determine the
repetition rate of the pulser. This can be a simple audio-ultra-
sonic oscillator, such a s the General Radio Type 1210-C unit
R-C Oscillator, Type 1301-A Low-Distortion Oscillator, Type
1302 Oscillator, or Type 1304-B Beat-Frequency Oscillator, or
i t can be a crystal oscillator with frequency dividers to produce
any frequency up to the 100-200-kc region. More complex sources
of time-coherent pulses are needed for the time-selection opera-
tions describedin paragraph 2.5.2. For these operations a timing
generator such a s the Tektronix Type 180, Dumont Type 300 or
equivalent can be used.
Choice of oscilloscope will depend on the application. An
oscilloscope with broadband video amplifier i s , of course, neces-
sary to permit observation of short-duration pulses. In order to
view the output pulse without degradation of rise time or shape,
the pulse must be amplified with a bandwidth in excess of 20
Mc, or e l s e the pulse must be presented by direct connection to
the oscilloscope deflection plates. Many applications, of course,
do not require that the ultimate rise times be attained, and for
these t e s t s l e s s complicated oscilloscopes can be used.
The waveforms shown in this section (Figures 2.1 through
2.7) are oscillograms taken directly from the screen of a Tek-
tronix Type 55 1 oscilloscope. Throughout the following sections,
the prf s e t by the timing oscillator will be 10 kc (100-psec peri-
od). The operator should a t first keep the dial settings in the
delay and sweep circuits considerably l e s s than this value. When
the delay or sweep-duration settings equal or exceed the period,
the oscilloscope patterns can become unstable or difficult to in-
terpret.
2.3
INITIAL CONTROL SETTINGS. Before turning the instru-
ment on, s e t the following controls a s indicated:
Control
Setting
TIME DELAY RANGE
10-100 p s e c
50-psec
TIME DELAY MICRO-
5.00
SECONDS
COINCIDENCE GATE
NORMAL
-
3
p s e c
DURATION
COINCIDENCE SEN-
NORMAL
SITIVITY
SWEEP TRIGGER
DIRECT
TRIGGER SELECTOR
POS GOING AC
TRIGGERING LEVEL
CENTER
PULSE AMPLITUDE
10
CIUTPUT IMPEDANCE
50
PULSE DURATION
5.0 on center s c a l e (50-psec pulse)
PULSE DELAY
0.5 on center scale (5-psec delay)
SWEEP MULTIPLIER
10
(60-psec sweep)
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