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20
E. DEFLECTION
COEFFICIENT
Set "Y /cm" (SK4) to "5 mY /cm" and "Y /cm"
(R2) to "CAL.".
Apply a 20 mV calibration voltage to the input
of the plug-in unit.
Adjust "GAIN
ADJ." (R1) so that the trace-
height amounts to precisely 40 mm.
It should be possible to reduce the trace height to
less than 16 mm with "Y /cm" (R2).
F. FREQUENCY
RESPONSE CURVE
After adjusting the square wave response (point D)
and the deflection coefficient (point E) the -3
dB
point of the unit should lie at a frequency of more
than 50 MHz.
The frequency response curve can be measured with
e.g. the PHILIPS A.M./F.M.-generator GM 2621
and the PHILIPS H.F.-millivo,ltmeter GM 6025. The
latter is to check that the input voltage remains con-
stant at the various frequencies.
-
Set "X-deflection" (SK7) on the basic oscilloscope
to "50 Hz".
Set "V /cm" (SK4) on the unit to "5 mY /cm" and
"Y/cm"
(R2) to "CAL.".
-
Connect the output connector HF II with a ter-
minated 50-Ohm cable to a T-piece which takes
in the HF probe of the millivo'ltmeter. Apply the
T-piece to the input terminal of the plug-in unit.
Switch the generator frequency to 10 MHz and
adjust the voltage to a 40 mm trace height. Note
the indication of the millivoltmeter.
Increase the frequency to 50 IVíHz and adjust the
amplitude to the same value as noted before.
The trace height should exceed 28 mm.
G. DEFLECTION
AND SHIFT
Before carrying out this measurement, check that the
DC balance and the sensitivity have been correctly
adjusted (see point C and E).
Set the " AC/DC" switch (SK3) to
66AC"
, "Y / cm"
(SK4) to "5 mY /cm"
and "Y /cm"
(R2) to
..CAL.".
Set "TIME / cm" on the basic oscilloscope to
"0.2 msec/cm".
Apply a triangular (or sinusoidal) signal with a
frequency of 2 kIJz and an amplitude of 90
ffiVn - o'
The control range of "SHIFT"
(R3) 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.
H.
AC/DC SWITCH; CHECK ZERO
Set the below mentioned knobs to the following
positions:
"AC/DC"
(SK3) to 66DC"
"Y/cm"
(SK4) to "5 mY/cm"
"Y/cm"
(R2) to, "CAL.".
-
Apply a 20 mV calibration voltage to the input
of the plug-in unit.
Adjust "SHIFT" (R3) so that the lower side of
the trace coincides with the centre line of the
screen.
Set SK3 to "AC".
The DC components of the calibration voltage
should be blocked, as a result of which the trace
is written approximately symmetrically around the
centre line of the screen.
-
Slowly depress button "Check Zero" (SK2).
First the signal should be visible in its differen-
tiated form and next, it should disappear com-
pletely.
I.
INPUT ATTENUATOR
1.
AttenuaÍion and square wave response
For the adjustment of the attenuator, in every posi-
tion of "Y / cm" (SK4), the corresponding trimmers
are accessible via holes in the screening plate (see
Fig. r4).
Apply the calibration voltage of the basic oscillo-
scope to the input of the PM 3332.
-
After correct adjustment of the deflection coeffi-
cient (see point E) the trace height should amount
to precisely 40 mm.
Check the trace height in all other positions of
SK4 according to the table below; the trace height
should amount to 40 ffiffi, + or
2Vo.
At the same time, adjust the trimmers mentioned
in the table for optimum square wave response.
Calibration
voltage
V /cm (SK4)
Trimmer
0.5 mY/cm
I
2
5
10
20
50
0. I V/cm
0.2
0.5
I
2
2mV
4
8
20
40
80
0.2v
0.4
0 .8
2
4
8
c3 1
c34
c38
c42
c46
c49
c53
c57
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