Table of Contents
Advertisement
GENERAL RADIO COMPANY
2.5.2.1
Internal Multiple P u l s e Method.
a. Connect an external audio oscillator (set for 10 kc) to
P R F DRIVE.
b. Set the TRIGGER SELECTOR switch to POS GOING
AC.
c. Set the COINCIDENCE SENSITIVITY control fully coun-
terclockwise.
d. Set the COINCIDENCE GATE DURATION control to 250.
e. S e t the TIME DELAY RANGE switch to the 100 p s e c - l
msec range.
f. Set the TIME DELAY MICROSECONDS dial to 9.20.
g. Connect the oscilloscope vertical-amplifier input to the
DELAYED SYNC OUT terminals.
h. S e t the oscilloscope writing rate a t 200 p s e c per divi-
sion.
i. S e t the oscilloscope for internal positive sync (or exter-
nal positive sync and connect sync input to the Type 1391-B
DELAYED SYNC OUT).
j. Connect a wire lead from the DIRECT SYNC OUT terminal
to the POS COINCIDENCE DRIVE terminal.
k. It may be necessary to advance the COINCIDENCE SEN-
SITIVITY control clockwise if the DELAY MONITOR lamp does
not come on when the SYNC and DRIVE terminals are connected.
1. T h e DELAY MONITOR lamp may go out when the TIME
DELAY MICROSECONDS dial is moved over each 100-psec.
point. T h e delay circuit can be started by means of the RESET
switch.
m. The oscilloscope pattern should be similar to that shown
in Figure 2.3B. A timing diagram showing the action of the in-
put and delay coincidence circuit is shown in Figure 1.4d, and
the action is explainedin paragraph 1.2.6.3. At this point it may
be necessary to readjust carefully the oscilloscope synchroniz-
ing controls to obtain a stable pattern since the waveform is
complex.
2.5.2.2
Time Selection, with an External Timing Generator.
a. Connect a 1-kc (1000-psec) pulse output from the timing
generator (amplitude over 10 volts) to the P R F DRIVE terminals.
b. Set the TRIGGER SELECTOR switch to SINGLE PULSE,
and for the appropriate-polarity.
c. Connect 100-psec pulse of either polarity from the timing
generator to the appropriate COINCIDENCE DRIVE terminals.
d. Connect the oscilloscope vertical-amplifier input to the
Type 1391-B DELAYED SYNC OUT terminals.
e. Connect the oscilloscope sync input to the P R F DRIVE
terminals.
f. S e t the oscilloscope synchronizing controls for the polar-
ity of the input pulse, and s e t the oscilloscope writing rate a t
200 p s e c per division.
g. Set the TIME DELAY RANGE switch to the 100-psec
-
1-msec range.
h. Set the TIME DELAY MICROSECONDS dial to 5.50.
i.
Set the COINCIDENCE GATE DURATION control to 200.
j.
Increase the setting of the COINCIDENCE SENSITIVITY
control from its counterclockwise limit until the indicator lamp
glows.
k. Experiment with the COINCIDENCE SENSITIVITY con-
trol to obtain maximum amplitude from the two delayed syn-
chronizing pulses that appear. Note that a l l 100-psec pulses ap-
pear when the control
is
in the NORMAL (clockwise) position.
Correct setting should yield a pattern similar to that shown in
Figure 2.7C.
1. The TIME DELAY MICROSECONDS and COINCIDENCE
GATE DURATION controls can now be varied to study the cir-
cuit action. The basic principles of operation of this circuit are
presented
in
paragraph 1.2.6.3, and Figure 1 . 4 ~ shows an ideal-
ized time diagram illustrating the time selection system.
m. Now obtain two delayed synchronizing pulses (as in step
k), and move the oscilloscope vertical amplifier input connec-
tion to the SWEEP POS terminals.
n. With the SWEEP TRIGGER switch a t DIRECT, note that
there is one 60-psec sweep sawtooth for each 1000-psec pulse
to the P R F DRIVE terminals.
o. Set the SWEEP TRIGGER switch to DELAYED, and note
that there is a sweep for each 100-psec timing pulse selected
(Figure 2.2D).
p. Repeat step 1, observing the sweep instead of the delayed
synchronizing signals.
2 . 6
SWEEP CIRCUIT
a. Set all controls to the positions given in paragraph 2.3.
b. Connect the prf drive oscillator, s e t at 10 kc to give a
100-psec time base, to the P R F DRIVE terminals.
c. Connect the oscilloscope vertical amplifier input to the
SWEEP POS terminals.
d. Connect the oscilloscope sync (or trigger) input to the
Type 1391-B DIRECT SYNC OUT terminals. Set the oscilloscope
for a positive synchronizing signal.
e. Set the oscilloscope writing rate to 20 p s e c per division.
f. With all equipment on and warmed up, check that the DE-
LAY MONITOR and SWEEP MONITOR indicator lamps are on.
If either indicator does not glow, flip the RESET switch. If both
lamps still do not glow, recheck the control settings against
those given in paragraph 2.3.
g. Note that one 60-psec sweep is generated for each input
cycle. The oscilloscope pattern should appear a s shown in Fig-
ure 2.2C.
h. Change the sweep duration to 30 by setting the SWEEP
DURATION pSEC control to 3 (with the SWEEP MULTIPLIER
switch still a t 10). Then generate 3-, 6-, and 12-psec pulses by
setting the SWEEP MULTIPLIER switch to 1 and switching the
SWEEP DURATION pSEC control to
3,
6, and 12.
i. Return the SWEEP MULTIPLIER switch to 10 and the
SWEEP DURATION pSEC switch to 6.
j. Connect the oscilloscope vertical amplifier input to the
SWEEP POS, GATE POS, and GATE NEG terminals and ob-
serve the negative sweep and the positive and negative gates.
Then return the oscilloscope connection to the SWEEP POS ter-
minals.
k. P l a c e the SWEEP TRIGGER switch in the DELAYED po-
sition to delay the start of the sweep 50 psec.
1.
Move the TIME DELAY MICROSECONDS dial to move the
sweep in time relative to the direct synchronizing pulse. The
delayed trigger may be lost if the delay setting exceeds 100
p s e c . If i t is lost, flip the RESET switch.
m. If the sweep controls are s e t for a duration in excess of
100 p s e c , the sweep circuit will ignore the triggers that occur
daring sweep time and thereby reduce the sweep recurrence rate.
Observe this effect a s directed in steps n and o.
Advertisement
Table of Contents
