You all caught me wearing my "engineering" hat, not my technician's hat.
Working in an development lab I often used a scope to study aberrations of a variety of signals, not just to see a nice square wave. As others pointed out, parasitics are often a much higher frequency than the fundamental signal and may not display at all on a low-bandwidth scope. The signal well look perfect even if it doesn't "sound" perfect. Any variation from a perfect sinusoidal signal requires that the amplifier be able to handle harmonics of the base frequency of the waveform. The more harmonics, the more accurate the display. The 10X bandwidth "rule" is strictly a "rule of thumb". In theory you need infinite bandwidth to reproduce a signal perfectly. As always, practice demands something less than theoretical perfection. If all you want to do is see *a* waveform on the display and not necessarily an accurate view of an unknown waveform that is being presented to the input, then by all means you can use a scope up to and even beyond its vertical bandwidth specs. Service technicians usually don't need the wide bandwidth of a lab scope. They commonly use a 'scope for a quick check on the frequency and amplitude of a signal and perhaps looking for any gross distortion that might be present. That's why so-called "Service Monitors" used on many tech benches include a simple 'scope that has a relatively low bandwidth compared to what's found in most engineering labs. Like using any tool, it's important to understand the limitations of the 'scope on your bench as well as its features. And speaking of features, I don't know the particular Tek scope being considered, but dual-trace capability is an invaluable feature to me. I often use the dual-trace capability to study the phase difference of two signals. Buying a 'scope is sort of like buying a personal truck to haul stuff around. We seldom understand the need closely enough to know exactly what we should get. And, no matter how big of a truck we might get, we'll eventually find something too big and heavy to fit in it! Still, that doesn't detract from its usefulness for hauling all the things that do fit. Ron AC7AC _______________________________________________ Elecraft mailing list Post to: Elecraft@mailman.qth.net You must be a subscriber to post to the list. Subscriber Info (Addr. Change, sub, unsub etc.): http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/subscribers.htm Elecraft web page: http://www.elecraft.com
