Hameg HM 1004-3 Series, Manual

Page: 16 / 36

Subject to change without notice
16
Controls and Readout
1mV/div up to 20V/div. The knob is automatically switched
inactive if the channel related to it is switched off, or if the
input coupling is set to
GD (ground).
The deflection coefficients and additional information
regarding the active channels are displayed in the readout,
e.g. “Y2: deflection coefficient, input coupling”. The
“:”
symbolizes calibrated measuring conditions and is re-
placed by the
“>” symbol in uncalibrated conditions.
(21)CH II - VAR. - Pushbutton with several functions.
CH II mode:
Briefly pressing the button sets the instrument to channel
II (Mono CH II) mode. The deflection coefficient displayed
in the readout indicates the current conditions (“Y2...). If
neither external nor line (mains) triggering was active, the
internal trigger source automatically switches over to
channel II (
“TR:Y2... ). The last function setting of the
VOLTS/DIV (20) knob remains unchanged.
All channel related controls are active if the input (31) is
not set to GD (33) .
VAR.:
Pressing and holding this pushbutton selects the VOLTS/
DIV. (20) control knob function between attenuator and
vernier (variable). The current setting is displayed by the
VAR-LED located above the knob.
After switching the VAR-LED (20) on, the deflection
coefficient is still calibrated. Turning the VOLTS/DIV.
(20) control knob counter clockwise reduces the signal
height and the deflection coefficient becomes
uncalibrated.
The readout then displays “Y2>...” indicating the
uncalibrated condition instead of “Y2:...” . Pressing and
holding the CHII pushbutton again switches the LED off,
sets the deflection coefficient into calibrated condition
and activates the attenuator function. The previous ver-
nier setting will not be stored.
The CHII pushbutton can also be pressed simultaneously
with the DUAL (18) button. Please note item (18) .
(22)TRIG. MODE - Pushbuttons and indicator LEDs.
Pressing the upper or lower button selects the trigger
coupling. The actual setting is indicated by a LED and by
the readout (“TR: source, slope, AC”).
Each time the lower TRIG. MODE pushbutton is pressed
the trigger coupling changes in the sequence:
AC (DC content suppressed),
DC (peak value detection inactive),
HF (high-pass filter cuts off frequencies below
approx. 50kHz), trigger point symbol switched off
NR (high frequency noise rejected),
LF (low-pass filter cuts off frequencies above
approx. 1.5kHz),
TVL (TV signal, line pulse triggering)
trigger point symbol switched off,
TVF (TV signal, frame pulse triggering)
trigger point symbol switched off.
~ (line/mains triggering) trigger point symbol
and
TRIG. LED (19) are switched off.
Please note:
In delay trigger mode (B timebase) the instrument is
automatically set to normal triggering mode and DC
trigger coupling. Neither setting is indicated by the
NM- (11) or the “DC” TRIG. MODE-LED. The previous
trigger settings regarding the A timebase remain un-
changed and are indicated by the LEDs (11) and (22).
In some trigger modes such as alternate triggering, some
trigger coupling modes are automatically disabled and
can not be selected.
(23)DEL.POS. - HO
Control knob with a double function and associated LED.
This control knob has two different functions depending
on the timebase mode.
A timebase:
In A timebase mode, the control knob applies to the hold
off time setting. If the HO-LED associated with the knob
is dark, the hold off time is set to minimum.
Turning the control knob clockwise switches the LED on
and extends the hold off time until the maximum is
reached (
please note “Hold Off-time adjustment” ).
The hold off time is automatically set to minimum (LED
dark), if the A timebase setting is changed. The (A) hold
off time setting is stored and active if alternate (A and B)
or B timebase mode is selected.
Alternate (A and B) and B timebase:
In alternate (A and B) and B timebase modes, the knob
controls the delay time setting.
Under alternate timebase mode conditions, the delay
time is visible on the A trace, beginning at the trace start
and ending at the start of the intensified sector. In the free
run condition (delay trigger not active) of the timebase, an
approximate delay time value is displayed in the readout
(
“
∆∆∆∆∆
t:...” ). This is an aid to find the position of the
intensified sector which may be very small.
If only the B timebase is being operated, the delay time
can also be varied, but there is no intensified sector as the
A trace is not visible.
(24)TIME/DIV. - The control knob has a double function.
The following description applies to the timebase switch
function (VAR LED dark).
Timebase Switch:
Turning the control knob clockwise reduces the deflec-
tion coefficient in a 1-2-5 sequence and increases it if
turned in the opposite direction (ccw.). The time coef-
ficient(s) is (are) displayed in the readout.