April 10, 2012

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Oscilloscope Basics

If you watch an electrical engineer tackling a tough design project, or a service engineer troubleshooting a stubborn problem, you’ll see them grab a scope, fit probes or cables, and start turning knobs and setting switches without ever seeming to glance at the front panel. To these experienced users, the oscilloscope is their most important tool but their minds are focused on solving the problem, not on using the scope.

Making oscilloscope measurements is second nature to them. It can be for you too, but before you can duplicate the ease with which they use a scope, you will need to concentrate on learning about the scope itself: both how it works and how to make it work for you. The purpose of this primer is to help you learn enough about oscilloscopes and oscilloscope measurements that you will be able to use these measurement tools quickly, easily, and accurately.

73,
~George N2APB, Joe N2CX and Alan W2AEW

Audio Recording ... (Listen to MP3 recording)

Text Log ...

<20:04:17>"Joe N2CX": Info for this weeks session: http://www.njqrp.org/teamspeak/Apr10.html
<20:12:34>"George - N2APB": Old Tek note from early 80's ... http://www.njqrp.org/teamspeak/scopes/XYZs_of_Using_a_Scope.pdf
<20:13:20>"Alan W2AEW": The Scopes4Dopes class video: http://www.youtube.com/watch? v=8ZKMrzTGxLQ&list=FLiqd3GLTluk2s_IBt7p_LjA&index=7&feature=plpp_video  
<20:13:23>"George - N2APB": Link to Alan's YouTube channel ... great stuff!  http://www.youtube.com/user/w2aew/videos
<20:15:55>"George - N2APB": Tek 465M is the most popular scope that Tektronix ever made!  (Hooray for me!)
<20:17:25>"George - N2APB": An oscilloscope allows you to see how signals vary with respect to time.
<20:36:58>"George - N2APB": Using "Add" and "Invert" mode, with two scope probes is a great way to see the voltage difference across a resistor (for example), and thus determine the current going through it.
<20:39:01>"George - N2APB": "Bandwidth Limit" switch can reduce the amount of noise that the vertical amplifier section is presenting to the displayed waveform.  Great tip!
<20:44:08>"George - N2APB": Can use a "50-ohm Through Terminator" on the scope input when attempting to accurately measure a 50-ohm output stage (for example).
<21:20:12>"John - KJ6CVB": Links to scopes suitable for HF bands?
<21:23:54>"Drew KZ9DRW": Are there any risks to using a 100 Mhz scope to look at reflected signal through a directional on 144 mhz antenna?
<21:34:33>"Terry WB4JFI": When discussing purchasing a scope, how about comparing traditional analog versus newer digital (sampling) scopes?
<20:00:31>"Pete - WB2QLL": Last week folks were raving about Xytronics 459. I ordered the Xytronic brass wool refill from Newark for $3.45 and it's very good. With the holder it's three times the price so I just ordered the refill and put it in a glass candle/vase thing, kinda like an ashtray.

SESSION NOTES ...

Material presented here is authored by Alan Wolke, W2AEW.  Email:  "alan dot wolke at gmail dot com", website:  http://www.dorkage.com

Here is the application note that the slide deck file was based on:  XYZ's of using a Scope.pdf

Here is the link to Alan's main YouTube Channel page: http://www.youtube.com/user/w2aew/videos   There are a few dozen videos there, most of them are geared around practical applications of oscilloscopes, geared towards the hobbyist/amateur. Things like "How to measure the length and impedance of coax with a scope," or "How to Monitor your ham radio with scope", etc. There are also videos that are more geared around high-end equipment and applications too, but it's all fun.

BASICS OF OSCILLOSCOPES

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REFERENCES

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