X-Position; Volts/Div - Knob (Ch1); Volts/Div - Knob (Ch2); Time/Div - Knob - Hameg HM400 Handbuch

17

X-POSITION

With this knob the display can be moved in X direction (horizontally). See
the paragraph above for its use together with the magnifi er.
18
VOLTS/DIV – knob (CH1)
This is a dual function knob: it is used to select the appropriate sensi-
tiviy for the signal at this channel's input, by pressing it shortly it will
assume the „Variable" (VAR) function (see below), while this is active,
the sensitivity indicators (ring of LEDs around the knob) will blink as
a warning that the sensitivity is now uncalibrated. The knob is only
enabled if CH 1 was activated or selected as the trigger source (CH1
only, dual trace, ADD, XY).
Sensitivity selection (Input attenuator)
If the sensitivity indicator LED does not blink, the sensitivity selected
will be calibrated. The sensitivity can be decreased CCW to 20 V/DV and
increased CW to 1 mV/DIV in 1 – 2 – 5 steps.
VAR (CH 1)
By pressing the VOLTS/DIV 18 knob shortly, its function will be changed
to „Variable" which will be indicated by blinking of the sensitivity indicator
LEDs around the knob. Pressing it again will restore the calibrated
sensitivity, the blinking will stop. As long as the variable function is
enabled, the display will be uncalibrated! CCW rotation will decrease
the sensitivity, CW rotation will increase it. The variable allows hence
to bridge the 1 – 2 – 5 steps of the sensitivity switch. If any of the two
limits of the variable range is reached, an acoustic signal will indicate
this. This function is frequently used e.g. for measuring rise times: be-
cause the rise time is defi ned from 10 to 90 % of the full amplitude, the
variable comes in handy to set the (uncalibrated) signal amplitude e.g.
precisely to 6 divisions peak-to-peak; by shifting the display horizontally
with the X position control, the rise time can be read from 6 mm from
the bottom to 6 mm below the top of the waveform.
19 VOLTS/DIV – knob (CH2)
This is a dual function knob: it is used to select the appropriate sensi-
tiviy for the signal at this channel's input, by pressing it shortly it will
assume the „Variable" (VAR) function (see below), while this is active,
the sensitivity indicators (ring of LEDs around the knob) will blink as a
warning that the sensitivity is now uncalibrated. The knob is only enabled
if this CH 2 was activated or selected as the trigger source (CH 2 only,
dual trace, ADD, XY).
Sensitivity selection (Input attenuator)
If the sensitivity indicator LED does not blink, the sensitivity selected
will be calibrated. The sensitivity can be decreased to 20 V/DIV CCW
and increased to 1 mV/DIV CW in 1 – 2 – 5 steps.
VAR (CH 2)
19
By pressing the VOLTS/DIV knob shortly, its function will be chan-
ged to „Variable" which will be indicated by blinking of the sensitivity
indicator LEDs around the knob. Pressing it again will restore the
calibrated sensitivity, the blinking will stop. As long as the variable
function is enabled, the display will be uncalibrated! CCW rotation
will decrease the sensitivity, CW rotation will increase it. The variable
allows hence to bridge the 1 – 2 – 5 steps of the sensitivity switch. If any
of the two limits of the variable range is reached, an acoustic signal
will indicate this. This function is frequently used e.g. for measuring
rise times: because the rise time is defi ned from 10 to 90 % of the
full amplitude, the variable comes in handy to set the (uncalibrated)
signal amplitude e.g. precisely to 6 divisions peak-to-peak; by shif-
ting the display horizontally with the X position control, the rise time
can be read from 6 mm from the bottom to 6 mm below the top of
the waveform.
20 TIME/DIV – knob
This knob has a triple function:
1. It selects the time base speed.
2. By pressing it shortly, it will assume the „Variable" VAR function,
this will be indicated by blinking of the LEDs around the knob.
POWER
F u n c t i o n o f t h e c o n t r o l s
18 19
VOLTS / DIV VOLTS / DIV
.2
.1
.5 50 .5
3
VAR
20
1 1
10
2 2
5 5 5
2
5 10 10
1
20 20
V mV V
6
DC DC
AC GND AC
CH 1
X-INP INPUTS
1 MΩ II 15 pF
max.
400 V
p
!
CAT I
29 36 30 31
32
3. After pressing the HOLD-OFF/ON
function of hold-off time adjustment, this will be indicated by the
button 34 lighting up, see under
The time base speed is selectable in 1 – 2 – 5 steps, turning the knob
CCW, it can be decreased to 0.2 s/DIV, turning it CW, it can be increased
to 100 ns/DIV, the speed will be indicated by the LEDs around the knob,
e.g. 10 μs(/DIV). By activating the X-MAG/x 10
further increased by a factor of 10 up to the maximum of 10 ns/DIV.
VAR
If the variable function was selected by pressing the knob shortly, the
time base speed can be reduced by turning it CCW and increased by tur-
ning it CW, uncalibrated. Whenever the limits are reached, an acoustic
signal will be heard. By pressing the knob again, the function variable
can be left any time and calibrated operation resumed.
Hold-off time adjustment: Please rever to item
21 CH 1 – LED button
This button selects CH 1 as the trigger source. In all operating modes
of the vertical amplifi er except XY, CH 1 can be selected as the active
internal trigger source by pressing this button which will be indicated
by the LED lighting up.
„Internal triggering" means that the trigger signal is
taken off internally.
22 CH 2 – LED button
STOP
This button selects CH 2 as the trigger source. In all operating modes
of the vertical amplifi er except XY, CH 2 can be selected as the active
internal trigger source by pressing this button which will be indicated
by the LED lighting up.
23 LINE – LED button
This button selects the line (mains) as the trigger source. In all ope-
rating modes of the vertical amplifi er except XY the line (mains) can
be selected as the active trigger source which will be indicated by the
LED lighting up.
„Line triggering" means that the trigger signal is not
derived from an input signal but from the mains and taken
from the power supply.
STOP
24 EXT – LED button
This button selects the external input as the trigger source.
In all operating modes of the vertical amplifi er except XY pressing
this button will select the external BNC input EXT.TRIG/Z-INP
the trigger source which will be indicated by the LED lighting up. The
external Z-INP for intensity modulation will be disabled.
21 25 27
23
22
24 26 28
TIME / DIV
.2 .2
.1
TRIGGER
ms
.5
50
1
20 CH 1 AC
2
10
5
CH 2 DC
10
5
20
2
LINE LF
50
1
.1s
mV
.2s
EXT TV
HOLD
OFF
GND INV ON
CH 2 EXT. TRIG / Z-INP
PROBE ADJUST
1 kHz / 1 MHz
ca. 0.2 Vpp
39
38
37 40
33 34
34 button, it will assume the
34 .
16
, the speed can be
34 .
Subject to change without notice
20
.1
50
VAR
20
10
5
2
1
.5
µs
.2
.1
Z-INP
1 MΩ II
15 pF
max.
100 V
p
35
40 as
41