Tektronix 310A, Instruction Manual, Page: 14 / 132

Operating Instructions-Type 310A
12. Turn the Variable VO LTS /D IV control throughout
its range. Notice that the UNCALIBRATED VE R TIC A L
light in the lower right corner o f the fro n t panel comes on
when the Variable VO LTS/D IV control is moved from the
C ALIBR ATED position (fully clockwise). The deflection
should be reduced to about tw o divisions in the fu lly coun­
terclockwise position. Return the Variable VO LTS/D IV
control to the C ALIBR ATE D position.
Triggering Controls
13. Rotate the TRIG LEVEL and S T A B IL IT Y controls
throughout their range. Notice that neither control has any
effect on the display in the AUTO position o f the Trigger
Coupling-Mode switch. Set the TRIG LEVEL control coun­
terclockwise and the S T A B ILIT Y control to PRESET.
14. Temporarily disconnect the inp ut signal. Notice that
a reference trace is presented. Reconnect the input signal.
15. Set the Trigger Coupling-Mode switch to AC. Slowly
rotate the TRIG LEVEL control clockwise until a display
appears. Notice that the display starts near the bottom of
the square wave. Continue rotating the TRIG LEVEL con­
trol clockwise and notice that less of the leading edge o f the
square wave is shown as the TRIG LEVEL control is turned
toward + (it may be d iffic u lt to observe this effect due to
the fast rise of the calibrator waveform).
16. Set the TRIG LEVEL and S T A B ILIT Y controls
fu lly clockwise. Notice that the display drifts across the dis­
play area, indicating that the time-base generator is free
running.
17. Slowly rotate the S T A B ILIT Y control counterclock­
wise until the display disappears. Now rotate the TRIG
LEVEL control counterclockwise until a stable display
appears. This setting o f the TRIG LEVEL and S T A B ILIT Y
control provides a stable display o f this signal, but may
need readjustment if the signal changes amplitude o r repeti­
tio n rate.
18. Set the S T A B ILIT Y control to the PRESET posi­
tion. The display should again be stable (if not, readjust the
TRIG LEVEL control fo r a stable display). This position of
the S T A B ILIT Y control automatically provides the correct
S T A B ILIT Y setting, and can be used fo r most applications.
Now, when the input signal changes amplitude or repetition
rate, only the TRIG LEVEL control needs readjustment.
19. Set the TRIGGER switch to —INT. The trace starts
on the negative-going part of the square wave. Return the
TRIGGER switch to + IN T ; the display starts w ith the
positive-going part of the square wave.
20. Set the Trigger Coupling-Mode switch to DC. Turn
the V E R TIC A L POSITION control clockwise until the dis­
play becomes unstable or disappears completely (only part
o f square wave may be visible). Return the Trigger
Coupling-Mode switch to AC; the display is again stable.
Since changing vertical position of the trace changes the DC
level of the internal trigger signal, this demonstration shows
how DC level changes affect DC trigger coupling. Return
the display to the center of the display area.
21. Connect the 10X probe (supplied accessory) to the
vertical INPUT connector. Connect the probe tip to a line-
voltage source. Set the TRIGGER switch to - LINE and
set the V O LTS/D IV switch fo r a display about fo u r d i­
visions in amplitude. If necessary, adjust the TRIG LEVEL
control fo r a stable display. Notice that the display starts
on the negative-going part o f the sine wave. Set the T R IG ­
GER switch to + LINE; the display starts w ith the positive­
going part o f the sine wave. Disconnect the probe.
22. Connect the C AL OUT binding post to the vertical
INPUT connector w ith the 18-inch BNC-to-banana plug
patch cord (supplied accessory) and to the EXT TRIG IN ­
PUT binding post w ith an 18-inch banana-plug patch cord
(for instruments between SN 10,000 and 20,474 use two
banana-plug patch cords). Set the TRIGGER switch to
+EXT and the VO LTS/D IV switch to .1. Operation of the
Trigger Coupling-Mode, TRIG LEVEL and S T A B ILIT Y
controls are the same as described in steps 12 through 20.
23. Disconnect the patch cord from between the CAL
OUT and EXT TRIG INPUT binding posts. Set the T R IG ­
GER switch to +INT.
Normal and Magnified Sweep
24. Set the T IM E /D IV switch to 1 MSEC and note the
CRT display. Then set the T IM E /D IV switch to 5 MSEC
and set the Horizontal Display switch to X5 MAG. The
display should be similar to that obtained w ith the
T IM E /D IV switch set to 1 MSEC and the Horizontal Dis­
play switch set to X I MAG.
2 5 . T u rn th e H O R IZ O N T A L POSITION control
throughout its range and note that the sweep is magnified
in both directions from the center vertical line. Any 10-
division portion o f the magnified sweep can be positioned
onto the viewing area w ith the H O R IZO N TAL POSITION
control. Return the T IM E /D IV switch to 500 p,SEC, the
Horizontal Display switch to X I MAG and return the start
o f the trace to the left edge of the graticule w ith the H O R I­
ZO N TAL POSITION control.
26. Turn the Variable T IM E /D IV control throughout its
range. Notice that the UNCALIBRATED TIM E BASE light
in the lower right corner of the fro n t panel comes on when
the Variable T IM E /D IV control is moved from the C A L I­
BRATED position (fully clockwise). The sweep rate is re­
duced as the Variable T IM E /D IV control is turned counter­
clockwise as indicated by more cycles displayed on the
CRT. Return the Variable T IM E /D IV control to the C A L I­
BRATED position.
External Horizontal
27. Connect the CAL OUT jack to the EXT HORIZ
INPUT binding post on the rear panel w ith tw o 18-inch
2-6