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30
H. DEFLECTION AND SHIFT
Before carrying out this measurement, check that the
DC-balance and the sensitivity of both channels have
been correctly adjusted (see points B1-2 and D).
Set the below mentioned knobs to the following
positions:
"A.C. D.C. (SK3-SKS) to "A.C."
"V/cm" (SK4-SK10) to ".O1 V"
"V/cm" (R3-RS) to "CAL."
"MODE" (SKS) and "TRIGG." (SK6) to "A"
Apply a triangular or sine-wave voltage with apeak-
to-peak value of 180 mV and a frequency of 2 kHz
to the A-channel.
The control range of "SHIFT" (R1) should be so
large, that the tops of the trace can be brought
within the measuring graticule.
With this triple overdriving. no distortion of the
trace should occur.
- Set "MODE" (SKS) and "TRIGG." (SK6) to "B".
- Apply the voltage to channel B and check in the
same wa.y as for A the shift and the deflection.
J. INPUT ATTE_~UATORS
1. Attenuation and square-wave response
For the adjustment of both attenuators, in every posi-
tion of V/cm (SK4 and SK10), the corresponding
trimmers are accessible from the outside of the atten-
uator (see Fig. 8).
Set "MODE" (SKS) and "TRIGG." (SK6) to "A"
(B).
- Apply the calibration voltage of the basic oscillos-
cope to channel A (B).
Adjust the calibration voltage to 40 mV. After cor-
rect adjustment of the sensitivity (see point D), the
trace height should amount to 40 mm.
Check the trace height in all other positions of
"V/cm" (SK4, SK10 resp.) according to the follo-
wing table; this trace height should amount to 40
mm ~ or — 22%.
At the same time, adjust the trimmers mentioned in
the table for optimum square-wave response.
Calibration
voltage
V/cm
(SK4—SKIO)
Channel A
Channel B
40 mV
.ol
80 mV
.02
C32
C132
.2 V
,OS
C34
C 134
.4 V
.1
C38
C138
.8 V
.2
C42
C142
2
V
.5
C46
C146
4
V
1
C49
C149
8
V
2
C53
C153
20
V
5
C57
C157
40
V
10
C61
C161
2. Input capacitance
With the aid of an input RC standardiser, (e.g.
Tektronix cat. nr. 011-0073-00 BNC) the input capa-
citance can be adjusted to 15 pF in all positions of
"V/cm" (SK4-SK10). See also Fig. 10.
Set "MODE" (SKS) and "TRIGG." (SK6) to "A"
(B).
Apply the calibration voltage of the basic oscillos-
cope to channel A (B) via the input capacitance stan-
dardiser.
- Adjust the input capacitance of both channels by
means of the trimmers mentioned in the table below
so, that the square-wave response is optimum..
Calrbration
voltage
V/cm
(SK4—SKIO)
Channel A
Channel B
80 mV
.Ol
C29
C129
(if necessary,
C28)
(if necessary,
C128)
.2 V
.02
C33
C133
.4 V
.05
C36
C136
.8 V
.1
C39
C139
2
V
.2
C43
C143
4
V
.5
C47
C147
8
V
1
C51
C151
20
V
2
C54
C154
40
V
5
C58
C158
80
V
10
C62
C162
K. BLOCKING OF CHANNELS A AND B
- Set "MODE" (SKS) to "A"
- In this position, channel B should be blocked. Check
this by turning "SHIFT" (R7); this should have no
\U
BNC-CONNECTOR
WG 101 96
~isPf
n
C
1M R 7W 1%
Fig. 10. Input RC standardiser
O
BNC-CONNECTOP
WL 101 66
PEM 7673
influence on the position of the time-base line.
- Set "MODE" (SKS) to "B".
- Check in the same way the blocking of channel A by
turning "SHIFT" (R1).
L. REJECTION FACTOR
- Set the below-mentioned knobs to the following
positions:
"POLARITY" (SK2) to "NORMAL"
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