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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 60 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 62 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). ~