User Manual

AC Adaptor Operation
The AC adaptor is connected to the rear panel 1.3mm socket marked DC IN; only the AC adaptor
supplied with the instrument should be used. When the AC adaptor is powered the red EXT
POWER lamp will be lit, whether the instrument is on or off; if the battery is being charged the
yellow CHARGING lamp will also be lit. The instrument has intelligent charging control to
optimise performance and battery life plus various protection measures; it is safe to leave the AC
adaptor connected for long periods of AC-powered operation though it is always good practice to
disconnect the adaptor from the AC supply and the instrument if the instrument is not in use.
The instrument can be turned off and on with the AC adaptor connected using the OPERATE key.
If the instrument has been turned off using the OPERATE key then it will stay off when AC power
is removed and when it is re-applied. If, however, the instrument is off when the AC adaptor
power is applied and had last been powered off by removing the AC power, then the instrument
will automatically power on and, when the AC adaptor power is removed, it will power off again.
This is useful when the instrument is part of a test set-up which is switched on and off with a
mains power master switch.
If the instrument is running on battery (or USB power) when the AC adaptor power is applied then
AC adaptor power will take precedence in powering the instrument and, when the AC adaptor
power is removed, the instrument will continue to operate from the battery (or USB power). It is
always good practice to disconnect the adaptor from the AC supply and the instrument if the
instrument is not in use for long periods.
Switching On
The instrument can be switched on and off with alternate presses of the OPERATE key, whatever
power source is being used. At power-on the default operating conditions are always as follows:
Input A, Frequency, AC coupling, 1MΩ input impedance, 1:1 attenuation, rising edge polarity, no
filter, 0.3s measurement time and no measurement hold; the associated annunciators will show in
the display. The threshold level is set by the position of the Threshold control.
If the RESET key is held down whilst the instrument is switched on using the OPERATE key, all
the annunciators will be shown in the display and for 2 seconds the main display area will show
the revision number of the installed firmware. After 2 seconds all the segments of the display will
show as a functional display check until the RESET key is released.
Press to Measure
With the instrument off, pressing any of the measurement function switches FREQUENCY,
PERIOD or WIDTH will power up the instrument and set the selected function; all other conditions
are defaulted as described above.
The instrument will then function normally and respond to all key presses. After a period of about
15 seconds with no key presses the instrument will automatically power down; this conserves the
battery if operating on battery power.
Input Selection and Configuration
Input A or Input B are selected with alternate presses of the INPUT SELECT key; an annunciator
in the display indicates which input is active.
Input A
Input A can be used for frequencies in the range 0.001Hz to >125MHz and has a number of
configuration options, described below, which allow it to count a wide range of waveform shapes
and amplitudes. The maximum input voltage and onset of clipping will depend on the coupling,
attenuation and input impedance settings and are given in the Specification.
The input is protected against temporary accidental connection of mains voltages up to 250Vrms
at 50/60Hz.
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