Fullscreen HTML5Med Res (??MB)HTML4

Product Review by LEO SIMPSON Tektronix TDS 2022 2-channel colour oscilloscope Did you swoon over the features of the Tektronix TDS 3014 and then blanch at the price? Well, Tektronix have now released a new range of LCD scopes, both monochrome and colour, at prices which are much more manageable. W e reviewed the TDS 3014 4-channel 100MHz Digital Phosphor Oscilloscope back in July 2001. At that time it was a considerable breakthrough in bringing Tek’s patented Digital Phosphor technology into a much cheaper package. Even so, we have to admit that the price would still be too steep for many prospective purchasers. Over the past year, we have published screen grabs from the TDS 3014 to illustrate many of our articles and we regard it as a very fine instrument. Fortunately, technology never stays still and many of www.siliconchip.com.au the features of the TDS 3000 series (although not the Digital Phosphor technology) are now available in a range of smaller LCD scopes. In fact, the size is similar if not identical to the revolutionary TDS 200 series released a few years ago. Smaller than a shoe box, this monochrome LCD instrument broke a lot of barriers and now the process continues. There are seven models in the new range. The TDS1002 and TDS 1012 are 60MHz and 100MHz 2-channel instruments. Then there are the five colour models: TDS2002 60MHz 2-channel; TD2012 100MHz 2-channel; TDS 2012 July 2002  65 Tektronix TDS 2022 Oscilloscope Here’s the long and the short of it (or should that be the short and the shorter?). These two photos show just how short in depth the TDS 2022 really is. Yet in that tiny box is packed a lot of ’scope! 100MHz 4-channel; TDS 2022 200MHz 2-channel and TDS 2024 4-channel. All have the same input, timebase and trigger facilities except for the 200MHz models which have a maximum sampling rate of 2 Gigasamples/second (2Gs/s) instead of 1 Gigasamples/second. We had the chance to sample the TDS 2022 for a few days and these are our reactions. First, this is a small instrument. While its front panel and screen size are virtually the same as a typical 2 to 4-channel analog scope, it has relatively little depth. Its dimensions are 324mm wide, 152mm high and only 125mm deep, including the knobs and rear projections. The LCD screen measures 115 x 88mm. The front panel has seven knobs and no less than 27 pushbuttons. On this model there are three BNC input sockets, one each for the channel inputs and one for external trigger (EXT TRIG) signal. The input sockets are not probe-sensing but probe division ratio can be set by push-button for the Ch1 or Ch2 menu to x1, x10, x100 and x1000. The power switch is on the top of the case, on the lefthand side. Input sensitivity can be switched over a range from 2mV to 5V/div in the usual 1.2.5 sequence but you can also use the Channel input menu (CH1 or CH2) to select fine sensitivity adjustment for the Volts/Div controls. In this case, the sensitivity can be set with 3-digit resolution; eg, 4.88V. The timebase can set for sweep speeds from 50 seconds/ div to 2.5 nanoseconds/div, again in the usual 1.2.5 sequence. Notice that 50 seconds per division is extremely slow and at this speed it takes 500 seconds for the trace to sweep across the screen! If you are used to an analog scope, this low-cost digital scope with LCD screen has facilities which were undreamed of when the analog scope was king. We’ve already mentioned on-screen menus and this is the great strength of the new digital scopes. In fact, this This series of photos demonstrate some of the measurement capabilities of the Tek TDS1000 & TDS2000 series scopes. Photo 1 (left) shows the scope displaying a 5kHz sinewave and square wave together with associated measurements. Photo 2 (right) shows the FFT analysis (harmonics shown in frequency domain) of the 5kHz square wave. 66  Silicon Chip www.siliconchip.com.au scope does not come with a printed manual. Every function is supported by on-screen help so if you are uncertain about a measurement, just press the “Help” button and then scroll through the text. Every button on the front panel is backed by on-screen menus, allowing you to make settings and select functions using the five buttons immediately to the right of the screen. Some of these functions require you to use one or more of the four small knobs on the front panel and the relevant knob will be indicated with a LED. For example, if you select cursors, the LEDs next to the two vertical position knobs light up to indicate that these are the ones to twiddle to move the cursors on screen. That’s a nice touch. Trigger menu The trigger menu on these new Tek scopes is quite impressive. You have a choice of Edge, Pulse or Video triggering. For pulse triggering you can set to trigger on a defined pulse width or when a pulse is greater, less than or not equal to the defined width. Video triggering is very impressive and you can sync on all fields, odd or even fields, all lines or select the line number (using the Trigger Level) control. And as in all other Tek scopes, you have a great range of measurements, apart from those possible using vertical or horizontal cursors. You can make measurements on channel 1 or 2 from the following list: Frequency, Period, Mean, Pk-Pk, Cycle RMS, Min, Max, Rise Time, Fall Time, Positive Width and Negative Width. Another impressive feature is the Math function. This allows you to add or subtract the channel 1 signal from channel 2 (or vice versa if you add the Invert function available from the channel input menu). More impressive is the incorporation of the Fast Fourier Transform (FFT) function so you can look at the signal in the frequency domain (using Hanning, Flat Top or Rectangular display). In previous reviews of digital scopes, we have generally managed to have on-screen pictures to demonstrate some of the performance features but our sample scope had no output interface. There is one available which will allow screen grabs to be printed out to a variety of printers but there is no inbuilt floppy disk option. So the screen photos you see here are just that: photos (with all their limitations). And to be honest, they really don’t do the screen complete justice. You may also be wondering how we managed to get the screen pics with no probes connected? No, it’s not trick photography. Notice the “Run/Stop” button top right of the TDS 2022 front panel? It freezes the current display until released. So we ran it, stopped it, unplugged it and snapped it! OK. In the time we had this scope we were not able to check every feature but generally we were very impressed. We do have a couple of minor quibbles. First, the feet to tilt the scope up to comfortably view the screen are just not big enough. The scope viewing angle is quite narrow both vertically and horizontally, so you do need to have the screen “square-on” as you look at it. Yes, you can tilt it up further using a book or two but the feet should be bigger. Easily fixed. Second, the contrast controls (Contrast Increase, Decrease) seem to have more effect on the brightness than the contrast; at least they did in our sample. Surely this should be easily fixed as well. Generally though, we think the new scopes will do very well. They are the easiest to use digital scopes we have come across and they are much more favourably priced than previous models. Where from, how much? The prices are as follows: TDS1002 60MHz, $2140 plus GST; TDS1012 100MHz, $2770 plus GST; TDS2002 60MHz, $2770 plus GST; TDS2012 100MHz $3410 plus GST; TDS2014 100MHz $4285 plus GST; TDS2022 200MHz, $5125 plus GST and TDS2024 200MHz, $5995 plus GST. The TDS2CMA Comms Module, giving GPIB, RS232 and Centronics Ports, is $560 plus GST. For further information on the new range of Tektronix TDS1000 and TDS2000 scopes, contact the Australian distributors, NewTek Sales Pty Ltd, 33 Paul Street North, North Ryde, NSW 2113. Phone (02) 9888 0100. SC Photo 3 (left) shows the leading edge of the 5kHz since wave and its rise time measurement of 132.5ns. Finally, photo 4 (right) shows the colour burst for a PAL video waveform. www.siliconchip.com.au July 2002  67