Category Archives: Troubleshooting

Review: Com-Power PAP-501 Broadband Preamp

I had a chance to visit Com-Power Com-Power ( in Brea, California, this last October, just prior to an EMC seminar I was presenting for the IEEE EMC Society – Orange County Chapter at CKC Laboratories just next door. Com-Power makes a variety of EMC measurement tools and probes and they graciously allowed me to review their broadband preamp.

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DIY 6 GHz Comb Generator

Most simple DIY comb generators seem to run out of steam about 1 GHz. I recently ran into David Bowman’s 2.4 GHz circuit and measured an upper usable range of about 6 GHz. While greatly attenuated above 3 GHz, this circuit should still be valuable for measuring semi-anechoic chambers in the GHz ranges.

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Unusual EMC Antennas

Is there anyone who has tried using unusual antennas for EMC troubleshooting or measurement? I’ve recently posted several ideas – some of which I’m actually using for troubleshooting.


Using a DTV antenna:

Using a PC board LP antenna:

A simple DIY dipole antenna (Part 1):—part-1

A simple DIY dipole antenna (Part 2):—part-2

An EMC troubleshooting kit (Part 1a):–Part-1a-Emissions-

DIY ESD Detector

ESD detectors are useful in correlating unusual circuit upsets with specific ESD events. The following is based on a simple lightning detector circuit by Charles Wenzel and written up later by Bob Radmore in the April 2002 issue of QST Magazine. It was since improved by Wenzel and described on his Web site. It turns out this circuit also makes a great ESD detector. I took the original circuit, added an LED lamp, piezo beeper and LCD counter to record the number of ESD events. More…

Figure 1 – Low-cost DIY ESD detector based on a circuit for a lightning detector.

Characterizing a Simple Dipole Antenna

As EMC engineers, we use many types of antennas – many broadband, these days. As a traveling EMC troubleshooter/consultant, I reply on small collapsible DIY antennas for troubleshooting, as described in an earlier blog posting.

In order to characterize these adjustable antennas versus frequency, it’s useful to be able to measure them with different element lengths extended, so that you know about where to set the length for the specific harmonics of interest. Using the new Rigol DSA815TG spectrum analyzer with tracking generator, and VSWR (voltage standing wave ratio) option, you can determine both the resonant frequency and VSWR, or how well the antenna is matched to the 50-Ohm coax cable. more…

Make Your Own EMC Troubleshooting Kit (Download)

I recently posted a new technical paper to my EMC web site: “Making Your Own EMC Troubleshooting Kit”. This downloadable pdf file includes a summary of the six-part series of articles on the Test & Measurement World web site in The EMC Blog. I describe the complete list of contents, plus some advice on selecting a low-cost spectrum analyzer.

Here’s the download…

Review: The ARRL RFI Book (3rd Edition)

In my never-ending quest to search out useful reference books on EMC, I recently ran into the 3rd edition of “The ARRL EMC Book” (ISBN 9780872590915). First published in 1999, the new 3rd edition was released in 2010. For those unfamiliar with the ARRL (Amateur Radio Relay League), this is the national organization representing amateur radio operators (“hams”) in the U.S. Most hams are members of the league, which also publishes a range of useful operating, design and general radio reference books. Because hams are allowed to operate their two-way radios at up to 1.5kW, on occasion, this may be the cause of local interference to poorly-designed or poorly-shielded consumer products. Thus, several years ago it was decided to publish a reference book on RFI (radio frequency interference). In this article, I’ll describe the most important content and why you might want to buy it. More…