HM203 is given as + 3 % , but as a rule it is considerably
better than this. For the simultaneous checking of
timebase linearity and accuracy at least 10 oscillations,
i.e.
1 cycle every cm,
should always be displayed. For
precise determination, set the peak of the first marker or
cycle peak exactly behind the first vertical graticule line
using the
X-POS.
control. Deviation tendencies can be
noted after some of the marker or cycle peaks.
The
20
and
lOms/cm
ranges of the
TIMEBASE
switch
can be checked very precisely with line frequency
(50Hz
only). On the
20ms/cm
range a cycle will be displayed
every cm, while on the
lOms/cm
range it will be every
2cm.
If a precise Time Mark Generator is used for checking.
Normal Triggering
(AT/NORM.
button depressed) and
LEVEL
control adjustment is recommended.
The following table shows which frequencies are re
quired for the particular ranges.
200ms/cm —
2 Hz
0.2 ms/cm -
5kHz
1 00ms/cm
10Hz
0.1 ms/cm - 10kHz
■ .......... —
20Hz
50jus/cm - 20kHz
20m s/cm —
50Hz
20//s/cm - 50kHz
10ms/cm — 100 Hz
1
0fislcm
-1 0 0 k H z
5ms/cm — 200 Hz
b/islcm
-2 0 0 k H z
2ms/cm — 500Hz
2/Us/cm - 500kHz
1 ms/cm —
1 kHz
1
fislcm
-
1 MHz
0.5ms/cm —
2kHz
0.5^s/cm - 2 MHz
The
time variable control
range can also be checked.
The sweep speed becomes faster by turning this variable
control clockwise to its right stop. One cycle at least
every
2.5cm
should be displayed (with
X-MAGN. X5
button in out position; measurement in the
50jus/cm
range).
When the
X-MAGN. X5
button is depressed, a marker or
cycle peak will be displayed every 5cm ± 5 % (with
variable control in
C
position; measurement in the
50yt/s/cm
range).
Component Tester
After pressing the
CT
button, a horizontal straight line
has to appear immediately when the
CT
socket is open.
The length of this trace should be approx.
8cm f50Hz)
or
7.4cm (60Hz)
respectively. With connection of the
CT
socket to one of the ground jacks in the Y-Section, a ver
tical straight line with approx.
6cm
height should be
displayed. The above stated measurements have some
tolerances. They are dependent among other things on
the mains/line voltage and frequency.
Trace Alignment
The CRT has an admissible angular deviation ± 5 ° be
tween the X deflection plane D1-D2 and the horizontal
center line of the internal graticule. This deviation, due to
tube production tolerances (and only important after
changing the CRT), and also the influence of the earth's
magnetic field, which is dependent on the instrument's
North orientation, are corrected by means of the
TR
potentiometer. In general, the trace rotation range is
asymmetric. It should be checked, whether the baseline
can be adjusted somewhat sloping
to both sides
round
about the horizontal center line of the graticule. With the
FIM203 in its closed case, an angle of rotation ± 0 .5 7 °
(1 mm difference in elevation per 10cm graticule length)
is sufficient for the compensation of the earth's magnetic
field.
Power Voltage Fluctuations
If a variable mains/line transformer is available, the
characteristics of the F1M203 on power voltage fluctua
tions of ± 1 0 % , referred to the voltage indicated by a
triangle (A ) below the fuse holder (rear panel), should be
checked. Under these conditions no variations should be
detected on the display in either the vertical or horizontal
axis.
T4 20 3-4
