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Operation
3 Operation
3.1
First time operation
Please note the following hints during first time operation:
❙ This instrument has a wide-range power supply designed
for 115 to 230 V, 50/60 Hz ±10 %, i.e. it will operate from
105 to 254 V.
❙ This instrument may only be connected to a wall outlet
with a three-conductor safety ground terminal or to an
isolation transformer of safety class 2.
❙ There are two fuses inside of the instrument which are not
serviceable by the customer.
❙ There are no visible damages to the instrument.
❙ There are no loose parts floating around inside.
3.2
Switch-on
After pressing the red POWER pushbutton
will show „3 GHz counter Hameg HM8123" and the cur-
rent software version installed, e.g. 1.03. During initializa-
tion the HM8123 will automatically load the configuration
stored in memory 0.
3.3
Display
The display will show the actual measurement function,
the result and the reference source (internal or external).
FREQUENCY A:
10.000000 MHz
Pressing the HOLD
button will activate the Hold func-
27
tion, the pushbutton will light up. The present result will
FREQUENCY A:
FREQUENCY A:
be frozen. The Hold function will be deactivated by pres-
10.000000 MHz
10.000000 MHz
sing the button again or by selecting another function. The
HOLD
pushbutton light will be off.
FREQUENCY A:
FREQUENCY A:
10.000000 MHz
–10.000 kHz
HOLD
REF: 100.000000 MHz
By pressing the pushbutton OFFSET
tion will be activated, the pushbutton OFFSET
FREQUENCY A:
FREQUENCY A:
light up. In this mode the present result will be taken as
–10.000 kHz
10.000000 MHz
the reference value and indicated in the display (e.g. REF:
REF: 100.000000 MHz
100.000000 MHz). For all subsequent measurements this
value will subtracted from the result, the difference will be
displayed.
FREQUENCY A:
10.000000 MHz
The following picture shows the display for a reference fre-
HOLD
quency of 100 MHz.
FREQUENCY A:
–10.000 kHz
REF: 100.000000 MHz
22
the display
1
Ref: INT
Ref: INT
Ref: INT
Ref: INT
Ref: INT
the Offset func-
29
will
29
Ref: INT
Ref: INT
Ref: INT
Ref: INT
3.4
Measurement functions
All measurement function are called by the function keys
to
. The selected function key will light up. The func-
A
M
tion selected will also be shown in the first line of the
display.
A
B
C
G
H
Fig. 3.1: The function keys and their meaning
FREQ A,
FREQ B,
A
B
Frequency measurement of the signal connected to the
channel selected. The frequency range of channels A
and B
is DC to 200 MHz and of channel C is 100 MHz
22
to 3 GHz. A high input sensitivity is not always desirable
for frequency measurements, as the counter will become
increasingly sensitive to noise on the signal. Hence fre-
quency measurements should be made using as much at-
tenuation as possible
13
gnal should be blocked by turning the DC pushbutton
light off. DC coupling, however, is necessary at frequen-
cies below approx. 10 Hz (DC Pushbutton lighted). In case
a low frequency signal is superimposed by high frequency
noise select the low pass filter LP 50 kHz
PER A : Period measurement of the channel A signal.
D
Measurement of the pulse width of the
WIDTH A :
E
channel A signal. Accuracy: 0.4% at squarewave (1 MHz)
A : B : Measurement of the frequency ratio of sig-
F
nals connected to channels A
surement is useful, for instance, for calibration of oscilla-
tors with odd frequency. The higher frequency should be
applied to INPUT A
to achieve the highest resolution
20
possible.
Measurement of the duty cycle of the chan-
DUTY A :
G
nel A signal. Accuracy: 0.4% at squarewave (1 MHz)
I In this mode Time Interval the time difference
TI A B :
H
between a signal on channel A
on channel B
(stop pulse) will be measured.
22
A B
Measurement of the average of the time
TI avg
:
I
interval A B.
Phase A B : Measurement of the phase difference
K
between signals A and B (only with square-wave signals
possible).
D
E
F
I
K
L
M
FREQ C
C
and
. Any dc content of a si-
16
.
18
and B
. A ratio mea-
20
22
(start pulse) and a signal
20
20
14
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