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5 mistakes to avoid when buying a low-cost scope

Posted: 03 Jun 2022 01:07 PM PDT https://www.kb6nu.com/5-mistakes-to-avoid-when-buying-a-low-cost-scope/?utm_source=feedburner&utm_medium=email


Keysight has a new application note—5 Common Mistakes to Avoid When Buying
a Low-Cost Oscilloscope—that you might want to get if youre going to buy a scope, or even if you use a scope. This free app note covers the following
five topics:

selecting an oscilloscope with insufficient bandwidth
settling for a USB oscilloscope
underestimating usability
running the risk of equipment support difficulties
focusing solely on specifications




Make sure you have enough bandwidth

A scopess bandwidth is the frequency at which the input signal sine waves attenuate by -3 dB (30%) as shown here:



From a practical point of view, what this means is that if you need to
measure the amplitude of a 146.96 MHz signal with some accuracy, dont
settle for a 150 MHz scope. The amplitude measurement at that frequency
could be up to 30% off. Youll probably want to purchase a scope with at
least 200 MHz bandwidth to make that measurement.

And, when measuring digital signals, having a scope with a high bandwidth
is especially important. The reason for this is that while a digital signal
may have a relatively low frequency, they contain higher frequency
components. Keysight recommends choosing a scope with a bandwidth at least
five times the highest clock rate in your system.
Dont settle for a USB scope

USB scopes are generally cheaper than stand-alone scopes with similar specifications, but remember that youll need a computer to provide the user interface. For one thing, its not going to be as portable as a stand-alone scope.USB scopes have their place, but probably not for general-purpose use. Dont underestimate usability

Even if you only use a scope occasionally, or perhaps especially if you
only use a scope occasionally, consider the usability of the scope you
intend to buy. Keysight notes that there are several factors contribute to
an intuitive and detailed graphical user interface (GUI). These include
display quality, display size, resolution, update rate, viewing angle,
color versus monochrome, and user-specified display modes such as variable
and infinite persistence. Additionally, a multi-language GUI can better contribute to the user’s interaction with the oscilloscope. Ideally, youd like to be able to play with a scope for a while before buying it.
Make sure that you can get support




Before you plunk down your cash, make sure that you can get support should
the scope you buy be DOA or fails after you start using it. Research the support and services offered by the vendor before buying to avoid
these  issues. A cheap scope with little or no support is not a bargain.
Dont focus solely on specifications





Keysight warns, Specifications do not tell the whole story. You need to dig deeper, read between the lines, and ask questions when researching oscilloscopes to select one that best fits your needs.

Ask  your friends what kind of scopes they have and if they like using
them. You can also head over to the EEVBlog Test Equipment Community Forum.
It now has more than a half million posts (!), and test equipment nerds
from all over the world hang out there.

This is just a quick review of the Keysight app note. Id suggest that you download and read the entire thing before buying your next cheap scope.











The post 5 mistakes to avoid when buying a low-cost scope appeared first on KB6NUs Ham Radio Blog.

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