Tektronix Type 82 PLUG-IN Instruction Manual page 48

13. Check AC-DC-GND Switch (Both Channels)
Place the Channel A AC-DC-GND switch to the AC posi-
tion. The waveform should shift downward about one centi-
meter to its average level. The shifting of the waveform
indicates that the switch and the input coupling capacitor
function properly. Switch AC-DC-GND switch to GND posi-
tion. The waveform should disappear. After making the
check, set Channel A AC-DC-GND switch to DC.
Apply the calibrator signal to Channel B. Set the MODE
switch to B ONLY and Channel B AC-DC-GND switch to
AC. Observe that the waveform shifts downward about
one centimeter. Switch AC-DC-GND switch to GND position.
The waveform should disappear. Return the Channel B
AC-DC-GND switch to its DC position.
14. Check V/CM Switch Attenuation
Ratios (Both Channels)
This step checks the calibrated deflection factors of the
Type 82 for both channels. While making the check, be sure
the VARIABLE VOLTS/CM controls are set fuily clockwise to
their CAL. positions. Then proceed as follows:
Use the Channel B VERTICAL POSITION control to align
the waveform with the horizontal graticule lines so the
amplitude measurement can be made easily. Check for
proper vertical deflection at each position of the Channel
B V/CM switch. Use Table 5-1 as a convenient guide. Ampli-
tude tolerance for each attenuator V/CM_ switch setting
should be within +6%. (V/CM switch attenuator and oscil-
loscope-calibrator tolerance are each +-3%. The tolerance
of the precision calibrator used at the factory to check the
Type 82 attenuators is + 1/4 %).
V/CM Switch Attenuation Check
V/CM Switch Amplitude Calibrator | Deflection
Setting _ | Output se incm
l 2 Volt 2
) | 5 Volt —T7 ~25-
5 | 1Volt [2
— tT fe ots
2 5 Volts 2.5
BRL 18 Volts fl
10 | 20Volts |
i 20S 50 Vols . 25 —
~~ 50% | 100 Volts a ae
* Found in plug-ins SN 3000-up.
After completing the check for Channel B, set the Ampli-
15. Channel A X1 POSITION RANGE
Fine Adjustment
Rotate the oscilloscope Stability control fully clockwise.
Set the Type 82 front-panel controls as follows:
V/CM (Chan. A} 2
VERTICAL POSITION (Chan. A} Centered (0°)
GAIN X10
If the trace moved off the screen, adjust the Channel A
X10 POSITION RANGE control to position the trace onto
the screen. Then adjust the Channel A X1 POSITION
RANGE control for minimum trace shift while rotating the
Channel A VARIABLE VOLTS/CM control. Keep the trace
on the crt by adjusting the Channel A X10 POSITION
RANGE control.
After adjusting for minimum trace shift, set the Channel
A VARIABLE VOLTS/CM control fully clockwise to the CAL.
16. Channel B X1 POSITION RANGE
Fine Adjustment
Set the Type 82 front-panel controls to these settings:
V/CM (Chan. B) 2
VERTICAL POSITION (Chan. B) Centered (0°)
MODE B ONLY
If the trace moved off the screen, adjust the Channel B
X10 POSITION RANGE control to position the trace onto
the screen. Then adjust the Channel B X1 POSITION
RANGE control for minimum trace shift while rotating the
Channel B VARIABLE VOLTS/CM control. Keep the trace
on the crt by adjusting the Channel B X10 POSITION
RANGE control.
After adjusting for minimum trace shift, set the Channel
B VARIABLE VOLTS/CM control fully clockwise to the CAL.
17. Channel B X10 GAIN Adjustment
Disconnect the coaxial cable from the Channel A INPUT
connector and connect the cable to Channel B INPUT con-
nector. Set the oscilloscope Amplitude Calibrator switch to
20 millivolts. Set the Type 82 Channel B V/CM switch to .01.
Adjust the oscilloscope Stability and Triggering Level con-
trols !o obtain a stable display.
Position the calibrator waveform to the center of the crt
with the B X10 POSITION RANGE control. Adjust Channel
B X10 GAIN control {see Fig. 5-2) so the waveform is exact-
ly two centimeters in amplitude.
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