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Kenwood CS-6020
1501\1Hz oscilloscope
with CRT readout
Kenwood's new CS-6020 150MHz oscilloscope
represents a big step forward in user facilities
for a given price. It features CRT readout to
display channel settings and it can display up
to 8 traces simultaneously.
panel. This helps make the controls
less cluttered and easier to use.
Even so, all the major operating
functions of the instrument are indicated on the front panel by rectangular LEDs.
Specifications
Below: voltage, time and frequency
measurements can be made quickly
and accurately by aligning two
cursors on the waveform. The
reading is displayed in the top right
hand corner of the screen.
voltage fields which sweep it across
the tube face to produce a visual
analog of the waveform being
measured. When it is producing
alphanumeric information on the
screen, it does so by the same
raster sweep process that is used
for TV screens and computer
monitors. The numbers and letters
are produced in a dot matrix, which
can be clearly seen if you look at
the numbers through a magnifying
glass.
Just how the instrument's electronics manage to produce both a
vector scan for the traces and a
raster scan for the alphanumeric
display is beyond the scope of this
article but it is a complex task
handled by a microprocessor.
Where this Kenwood instrument
differs from most earlier CROs with
CRT readout is that since the CRT
shows most of the settings on the
screen, a lot of the labelling has
been eliminated from the control
Essentially, the Kenwood CS6020 can be regarded as a 2-plus2 trace oscilloscope. Channels 1
and 2 have full input attenuators
while channels 3 and 4 are auxiliaries with only two input sensitivies available.
Channels 1 and 2 have a sensitivity of 5mV to 5V/division
selected via a rotary attenuator
switch with a 1-2-5 sequence. The
upper - 3dB frequency response on
these ranges is 150MHz. For the
same channels, a sensitivity of
lmV/division is available but with
the - 3dB response reduced to
20MHz. Either channel may be AC
or DC coupled.
Channels 3 and 4 have a sensitivity of 0.1 V or 0.5V/division
(selected via pushbutton switches)
and a frequency response to
150MHz ( - 3dB). Both of these
channels are DC coupled only.
The horizontal axis input is via
channel 2 and this has the same
Voltage measurement
Time measurement
Frequency measurement
Oscilloscopes with CRT readout
(ie, channel settings displayed on
the screen) have been around for
quite a few years but this feature is
now becoming available on much
cheaper instruments. Briefly, the
oscilloscope beam is made to do
double duty; it not only displays the
various traces that are required
(which can be up to 8 on this model),
but also displays the various input
settings for the four channels, the
timebase settings and other data
such as the time and date.
Normally, oscilloscope traces are
produced by the vector scan
method; the electron beam is subjected to vertical and horizontal
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SILICON CHIP
Despite its impressive range of features, the CS-6020 is easy to use. Most of
the control settings are displayed on the CRT, thus eliminating a lot of
labelling from the front panel. The unit can display up to 8 traces
simultaneously and either horizontal or vertical cursors.
sensitivity as when used in the vertical mode but the frequency
response is reduced to 2MHz.
The vertical mode to be displayed is selected by the following
pushbutton switches: CHl, GHZ, CH3,
CH4, ADD, CHOP/ALT, GHZ INV and
20MHz BWL (bandwidth limited).
Two timebases
There are two horizontal timebases: main (A) and delay (B). They
may be selected as A only, A INT B (B
displayed as an intensified portion
of the A sweep), ALT (A sweep intensified for duration of B sweep, alternating with delayed B sweep), B
sweep only and X-Y when CHl, CH3,
CH4 may be used for the vertical inputs and CH2 for the horizontal
input.
Sweep speeds are selected via a
rota·ry switch and range from 20ns
to 0.5s/division. Trigger delay of the
delayed sweep (B) is from 0.2 to 10
times the A sweep time setting. A
x 10 magnification function is also
available via a pushbutton switch,
giving a maximum sweep speed of
.02ns/division.
Triggering of the timebase can be
from any of the four vertical inputs
and line (ie, 50Hz mains supply).
Trigger coupling may be AC, DC,
Noise or HF rejected, TV Frame or
TV Line.
Triggering
Trigger mode may be Auto/Normal, Single Shot and Fix. This last
mode is interesting in that it overrides the Trigger level control and
triggers the timebase close to the
zero crossing of the input waveform. This greatly simplifies stable
triggering of difficult signals and
makes the CRO that much easier to
drive.
The B sweep has a further mode:
TRIGGER COUNT. When the CRO is
used for observing TV signals the
TRIGGER COUNT · switch is pushed
and the required trigger count
number (n) can be set using the
LiREF/DELA Y POSITION control. The B
sweep then triggers on the nth
count of all the TV synchronising
pulses (equalising, vertical and
horizontal). In this mode the complete TV frame signal is displayed
by the A sweep and the required
line signal is displayed by the B
sweep.
CRT readout
Two lines of alphanumeric data
are displayed on the screen. At
switch-on, the line at the top of the
screen indicates the month, date,
year and time. The main functions
displayed on the line at the bottom
of the screen include the vertical
sensitivity of the selected channel
or channels, and the selected
sweep speed for the main and
delayed timebases. When either the
vertical input or timebase VARIABLE
controls are used, the relevant
readout is preceded by a ) symbol.
Two horizontal cursors can be
placed on the screen to measure
voltages on different parts of
waveforms. Similarly, two vertical
cursors can be placed on the screen
for the measurement of time delay,
frequency , phase or ratio.
When the cursors are in use, the
top line of the display shows (in addition to the time and date) the
voltage difference between the cursors for either channels 1 or 2 when
the input attenuator is in the
calibrated position. Alternatively, it
displays the voltage ratio between
SEPTEMBER1990
61
Kenwood CS-6020 1~0 MHz Oscil,oscope
Voltage ratio measurement
Time ratio measurement
Phase measurement
Rise time measurement
Delay measurement
Trigger counter
These photos show some of the other measurements that can be made using
the cursors. The trigger count function is shown at bottom right. The top trace
shows a composite video signal at a sweep speed of 5ms/div, while the bottom
trace shows line 312 at O.lms/div.
the cursors as a percentage (with
five vertical divisions representing
100%) when the input attenuator is
uncalibrated ie, when the
VARIABLE control of the attenuator
is adjusted away from the CAL
position.
Similarly, if the vertical cursors
are in use, the top text line shows
the time difference or 1/time (frequency) between the cursors.
Other information displayed can
be the phase difference between
the cursors (with five horizontal
divisions representing 360°) when
the timebase variable control is used, or the delay time when sweep B
is active.
Use of the cursor controls is uncomplicated and simply requires
selection of the wanted function
(~Vl, ~T. etc) by the relevant
pushbutton switch. The ~REF/DELAY
POSITION control is then used to
position the first cursor to the part
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SILICON CHIP
of the waveform from which the
start of measurement is to be made.
The ~ control is then adjusted to
place the second cursor at the end
of the measurement and the
readout displays the value in the
top right-hand corner of the screen.
In this way measurements can be
made of waveform amplitude or
period in whole or in part.
Measurement accuracy for voltage or time is ± 3 % but as making a
measurement depends on careful
positioning of the cursors by the
user, this also becomes a factor in
the final accuracy. Because of the
measurement method, even if there
is no signal input, a reading will be
indicated, dependent only on the
positions of the two cursors on the
screen.
Probe switching
Two divide by 10, 150MHz probes are supplied with the CS-6020.
Plugging these probes in means that
the vertical input sensitivity is
automatically reduced by 10, for
example from 5V/div to 50V/div.
This could cause confusion when
taking measurements off screen but
Kenwood gets around it by using
special probes which have a pin at
their connector end. When plugged
into the CHl or CH2 inputs, they
change the readout accordingly.
We 11l have one
Despite the number of functions
the CS-6020 provides, we found it a
very easy and pleasant instrument
to use. This is in contrast to many
CROs which can require a lot of
time just to get a trace on the
screen, let alone make measurements.
Price of the Kenwood CS-6020
oscilloscope is $3980 plus tax,
where applicable. This includes the
two special probes. For further information, contact Elmeasco Instruments Pty Ltd, PO Box 30, Concord, NSW 2137. Phone (02) 736
2888. [LDS & RF).
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