Tektronix 1A5 Instruction Manual page 28

Operating Instructions — Type 1A5
venient DC source can be substituted and the sensitivity
of the Type 1A5 set accordingly.)
Type 1A5 set-up
Vc POLARITY
POSITION
AC-GND-DC (A Input)
A INPUT
VARIABLE
DISPLAY
a. Perform the STEP ATTEN BAL adjustment as outlined
in the front panel adjustment procedure.
b. Set the VOLTS/CM switch to .5 V.
c. Use POSITION control to set the trace to DC-0 refer
ence.
d. Place the A Input AC-GND-DC switch to DC.
e. Multiply centimeters of deflection by deflection factor
(3 cm × . 5 V). Input voltage amplitude is 1.5 V.
Note that if the input had been applied to the B INPUT
terminal and the DISPLAY switch set to Vc-B, the deflection
would have been downward, since the B INPUT causes an in ­
verted presentation.
Example 2. Differential
measurement. Measure the voltage output of a 1.5 V bat ­
tery.
Type 1A5 set-up
Vc POLARITY
POSITION
AC-GND-DC (A Input)
A INPUT
VARIABLE
DISPLAY
a. Perform the STEP ATTEN
in front panel adjustments.
b. Set the Vc AMPLITUDE to expected input voltage.
(1.5 V on 5 V range. Setting 1 -5-0.)
c. Set the VOLTS/CM control to 20 mV.
d. Us ing POSITION control, set the trace to DC zero
reference.
e. Simultaneously place A Input AC-GND-DC switch to
DC, and Vc POLARITY switch to the polarity of the input
voltage, + .
f. Using Vc AMPLITUDE control, reset the trace to DC
zero reference.
2-20
0
Centered
GND
Connected to battery
positive terminal. (Con ­
nect battery negative
terminal to Type 1A5
Ground terminal.)
CAL
A-Vc
Comparator Operation, DC
0
Centered
GND
Connected to battery
positive terminal. (Con ­
nect battery negative
terminal to Type 1A5
Ground terminal.)
CAL
A-Vc
BAL adjustment as outlined
g. Read the value of the input voltage from the Vc AMPLI ­
TUDE dial, +1.5 V.
Example 3. Single-Ended Operation — waveform meas­
urement. Measure the oscilloscope Cal Out waveform and
DC level.
Type 1A5 set-up
POSIHON
AC-GND-DC (A Input)
AC-GND-DC (B Input)
A INPUT
VARIABLE
DISPLAY
a. Perform the STEP ATTEN BAL ad j usiment as outlined
in front panel adjustments.
b. Set the VOLTS/CM control to 10 mV position.
c. Set the oscilloscope Amplitude Calibrator control to
50 mV.
d. Place A Input AC-GND-DC switch to its AC position.
Set the oscilloscope triggering controls as necessary for a
stable presentation.
e. Compute AC waveform amplitude, using the POSITION
control as necessary to set the waveform to a reference
line. (5 cm deflection times 10 mV deflection factor equa l s
50 mV.)
f. Determine the DC level on which the waveform is riding.
Do this as explained in example 1 or 2, mating the DC level
of the top, middle or bottom of waveform, as desired.
Note that for signals with a high AC to DC ratio, the AC
and DC components can be evaluated simultaneously by
us in g DC coupling and single-ended operation methods.
If a very low frequency is involved (less than 2 Hz), the
waveform measurement must be made using DC input coupl ­
ing. AC and DC signal components can be determined simul ­
taneously by introducing Vc to offset the DC component. The
AC component can be determined by comparison against the
CRT graticule and the DC component can be read from the
Vc AMPLITUDE dial.
Example 4. Differential Amplifier Operation.
the difference between the oscilloscope Cal Out waveform
and modified Cal Out waveform.
Oscilloscope set-up
Set the Amplitude Calibrator control to Off.
Connect a BNC T adapter to the Cal Out connector.
Build and connect a voltage divider to the BNC T as
illustrated in Fig. 2-15.
Type 1A5 set-up
POSITION
AC-GND-DC (A Input)
AC-GND-DC (B Input)
Centered
GND
GND
Connected to oscilloscope
Cal Out connector via
coaxial cable
CAL
A-B
Measure
Centered
GND
GND