Hameg Dremel 4000 Handbuch Seite 37

Select MARKER with the pushbutton, the LED will light
up. At the same time the crt display will show the marker
as a bright spot of appr. 1 mm. The LCD display will show
at the top left the marker frequency (M293.002 MHz) und
below the marker level L –25.5 dBm), these values, of
course correspond to the marker position on the screen..
The marker can be moved using the knob. The keyboard
is disabled if MARKER is active.
Please note:
If the level of any signal portion transgresses the top
graticule line it will not only no more be visible, but the
measuring amplifi er's linear range will end at approx.
+2.5 dB above the graticule top. The signal will then be
limited which causes distortion and false measure-
ments! Therefore LIMIT will be displayed if any signal
portion will reach +2.5 dB above the graticule top (=
reference level).
TUNING – The values of the following functions can be set
with this knob: FOCUS/TR
, CENTER FREQ. , MARKER
PHONE % . That function is active the LED of which is
lit.
REF.-LEVEL – Setting the reference level.
The function is selected by pressing the pushbutton, the
LED will light up. The value can be chosen either with the
knob TUNING or by entering it into the keyboard and
pressing the pushbutton again. The display will show e.g.
R-10.0dBm.
Changing the reference level does not infl uence the sen-
sitivity. If the noise band is at the bottom of the display the
reference level can not be increased, only decreased, at
the same time the noise band will shift upward decreasing
the dynamic range.
The entry of values outside the specifi cations is not possib-
le, the entry will be automatically corrected. The attenuator
setting will not be affected.
PHONE % – Headphone volume.
The connector is a 3.5 mm type and destined for head-
phones with an impedance ≥ 8 Ω.
The volume is set with TUNING
from an AM detector and may be used to identify sources
of interference. The spectrum analyzer may be used as a
receiver by connecting an antenna to the input, with zero
span it can be tuned to individual frequencies. Use as a
receiver may be restricted by laws in certain countries!
Press the pushbutton shortly, this will select the head-
phone volume control. The LED will light up.
As soon as another function is selected this function will
be deactivated.
INPUT 50Ω – Measurement input, max. 25 V
+10 dBm HF. With the attenuator set to 40 dB the maximum
input HF signal is +20 dBm. Higher levels may destroy the
input stage.
, INTENSITY , CONTRAST
, REF.-LEVEL and
. This signal comes
resp. max.
DC
C o n t r o l s a n d c o n n e c t i o n
The N connector is directly connected to the chassis and
thus with the safety earth of the power plug!
PHONE – Headphone output connector, 3.5 mm. This
output is destined for headphones with an impedance of
≥8 Ω. The volume can be set after activating PHONE-
LEVEL % with the TUNING knob
ATTEN. – Input attenuator.
The pushbuttons belonging to the attenuator allow selec-
tion of 10 to 40 dB of attenuation in 10 dB steps. Depending
on the setting selected the maximum signal level will be:
Max. signal level
–30 dBm
–20 dBm
–10 dBm
0 dBm
+10 dBm
In the 0 dB position the maximum signal level
which can be displayed will be –30 dBm, but this
setting should be avoided resp. only used if neces-
sary.
Please note:
In order to protect the delicate input stage the 0
dB position can only be accessed out of the 10 dB
position and after pressing the 0 dB pushbutton for
a long time.
The maximum permissible input levels must not
be exceeded, otherwise the input stage may be
destroyed. The spectrum analyzer displays in
general only such frequencies inside its limits of
150 kHz to 1050 MHz, however, it is possible that
the input signal contains high levels of hf outside
these limits!
HINT
VBW – Video fi lter
This fi lter averages the noise and thus will in general re-
duce it, this may make small signals visible.
As the response time of fi lters precludes too fast
a sweep a large span may not be acceptable with
the video fi lter switched in; this will be indicated by
UNCAL. If this message is shown reduce the span.
First use CENTER FREQ. to shift the signal to the
STOP STOP
display center, then reduce the span.
RBW – Choice of resolution bandwidths 500 or 20 kHz. The
respective LED will indicate which was selected.
Depending on the IF bandwidth the spectrum analyzer
will be able to more or less separate frequencies. E.g. at
20 kHz RBW 2 signals 40 kHz apart can be recognized as
separate; at 500 kHz RBW both would melt into one signal.
However, the smaller bandwidth requires a slower sweep,
otherwise the fi lter output can not rise to its correct value,
hence the amplitude shown will be too small. In case the
4 kHz video fi lter is also switched in the span must be
further reduced. UNCAL in the display will be shown if
the sweep is too fast. Of, course, as the noise depends on
bandwidth a smaller bandwidth will decrease it.
.
Attenuator setting
0 dB
10 dB
20 dB
30 dB
40 dB
Subject to change without notice
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