Hameg HM2005-2 User Manual Download Page 32

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Subject to change without notice

C o n t r o l s a n d R e a d o u t

CH1 VAR

(pushbutton)

This pushbutton opens the CH1 menu which contains the
following options referring to CH1

input respectively to the

signal on CH1.

27.1 AC DC

Pressing the pushbutton will switch from AC to DC or vice versa.
The mode selected will be shown in the readout following the
sensitivity setting: ~ is for AC and = is for DC.

27.1.1

DC coupling

The signal will be directly coupled, from the BNC connector via
the attenuator to the vertical ampliﬁ er. The input resistance is
1 MΩ in all positions of the attenuator.

27.1.2

AC coupling

A capacitor is inserted between the BNC connector and the
attenuator, blocking the DC content of the signal and creating a
low frequency cut-off at approx. 2 Hz. This will affect the shape
and amplitude of signals with low frequency content. If the DC
content of the signal changes or the duty cycle of pulses the
capacitor will charge or discharge, this will cause a momentary
Y shift of the display.

27.1.3

50Ω / 1 MΩ Input Impedance

This function allows you to select the input impedance of chan-
nel 1. For measurement of low and high frequencies, voltages
at sources with impedances deviating from 50Ω an impedance
setting of 1 MΩ is recommended, together with the use of a
frequency compensated divider probe for minimum capacitive
load.

If the source impedance is 50Ω and the voltage to be measured
is within the voltage limits a 50Ω cable and 50Ω impedance
setting should be used.

27.2 Ground On Off

The pushbutton will either connect the ampliﬁ er to the signal
or to ground. If set to Ground the readout will show a ground
symbol following the sensitivity setting, at the same place where
formerly the coupling was indicated. In the Ground position and

with automatic triggering a trace will be visible, this is handy for
setting the Y-position of it e.g. to the screen centre without dis-
connecting the signal. The readout will show a symbol ( ) for 0 V
which will be close to the vertical centre line of the graticule, it is
the zero reference for any measurements. After switching back
to the signal its amplitude can now be determined with respect
to the formerly set zero reference.

27.3 Invert On Off

(unavailable in XY-mode)

This pushbutton will alternate between not inverted or inverted
of the CH1 signal. The readout will indicate an inverted display
by placing a bar above the CH1. The trigger signal derived from
CH1 will not be affected by an inversion.

27.4 Variable On Off

If activated (“On” intensiﬁ ed) the CH1 VAR pushbutton

will

be illuminated and the VOLTS/DIV VAR knob

will function

as variable which can change the sensitivity continuously
between 1 mV/cm to

20 V/cm. If in uncalibrated position, the

readout will replace ”:“ by ”

“ (e.g. ”CH1

5mV“.) and this also

in any cursor measurements pointing out that the sensitivity
is uncalibrated.

Pressing the “Variable On Off” function key again, switches
“Variable” off and the VOLTS/DIV VAR knob

back to calibrated

1-2-5 sequence deﬂ ection coefﬁ cient function.

27.5 Probe

The menu display depends on whether the probe has dividing
ratio identiﬁ cation. The value (automatically or manually selec-
ted) will be automatically taken into account regarding the
sensitivity indicated and measurements.

27.5.1

If a HAMEG probe with automatic dividing ratio identi-

ﬁ cation is used, the menu display shows in normal intensity
“Probe” and beneath the dividing ratio (e.g. “*10”).

27.5.2

If no probe or a probe without automatic dividing ratio

identiﬁ cation is used, the menu displays “Probe” and beneath
the last manually selected dividing ratio: the INTENS knob

symbol. Pressing the allocated function key causes “Probe” to
be displayed intensiﬁ ed and the FOCUS TRACE MENU push-

VAR

x10

FOCUS
TRACE

VOLTS / DIV

VAR