Always on the lookout for useful, but inexpensive test equipment, I recently ran across the Triarchy Technologies USB spectrum analyzer, model TSA5G35. The one thing that really struck me was the whole thing was built into a USB dongle, just a little larger than a memory stick. What’s more, the advertised frequency range was 1 MHz to 5.35 GHz. This, I had to see for myself.
So, is a spectrum analyzer no larger than a pack of chewing gum that you can carry in your pocket good enough for EMC analysis and troubleshooting? For a total cost of $599 (through their store on eBay), I decided to take a chance and run this remarkable PC-based analyzer through the ringer.
Figure 1 – Photo showing the analyzer with supplied USB extension cable and 30 dB attenuator.
Figure 2 – A screen capture of a series of 16 MHz oscillator harmonics.
SPECIFICATIONS – Basic specifications include frequency coverage of 1 MHz to 5.35 GHz, resolution bandwidths of 50 through 500 kHz (not selectable), frequency spans from 1 MHz to 1 GHz, input level range of -110 to +30 dBm (using the supplied 30 dB attenuator for the higher power levels), and typical noise levels of -80 to -100 dBm (depending on the span and RBW). The maximum power level is +20 dBm for 1 minute (without the external attenuator) and +/- 25 VDC, which is excellent protection for this little instrument. The reference level range is -60 dBm to 0 dBm (no external attenuator) or -30 dBm to +30 dBm (with the external attenuator. the usable display range is 80 dB with a noise floor of -115 dBm at a 5 MHz span and -60 dBm reference level at 1 GHz. Amplitude accuracy is specified at less than 3 dB. All in all, not to bad for this little guy.
For more of this hands-on review on Test & Measurement World, click here…
I was honored to be the featured speaker at the 13th annual EMC Society Chapter of the IEEE Milwaukee Section “EMC Mini-Symposium” this last March 19th. Hosted and managed by EMC engineer Jim Blaha (GE Medical), this was actually no mini-symposium – but is the largest regional gathering of EMC engineers in the country. There were a record 180 engineers from around the area, as well as a record 42 vendors showing their wares. The event sold out within just a few weeks.
The title of my talk was a mouthful: “EMC Essentials and Pre-Compliance Testing with your own Affordable EMC Troubleshooting Tools Kit”. While I covered some of the major EMC theory for issues I generally end up addressing at various client companies, most of the day was spent on how to collect a set of useful tools, probes and measuring instruments to make up a portable EMC troubleshooting kit. I then went on to explain how I use these tools to perform pre-compliance and evaluation testing of prototype products.
I’d like to thank Jim Blaha for his superb organization and management of the event, all the vendors, who helped sponsor the event and Agilent Technologies for supplying the oscilloscope and spectrum analyzer for the demonstrations.
Here are a few pictures taken by my colleague and fellow EMC consultant, Jerry Meyerhoff. Thanks Jerry!
Jim Blaha from GE Medical manages the symposium and is providing introductory comments.
Chatting during one of the breaks.
A portion of the 180 attendees.
Here I am explaining why pigtail shield connections cause common-mode currents resulting in radiated emissions.
A very full house!
For those of you who regularly troubleshoot EMC issues, wouldn’t it be convenient to have all your “fix-it” parts all in one place? That’s what I thought as I was wandering around JoAnns (a fabric and hobby store) with my wife. I spotted this “photo keeper” storage box and thought it would be perfect to store all the little parts, gasketing, filters, etc., for quickly implementing fixes during the troubleshooting process.
I had a chance to use this kit in a real-life consulting application as I helped a client in Chicago recently. I transported the kit inside a large Pelican case and used a quantity of bubble-wrap to protect it from shifting around. It survived just fine and added a sense of professionalism in the client’s eyes.
Hobby stores sell many similar storage boxes and you may find several to your liking. Read on for more details…
These unusual EMI sources may be used to perform pre-compliance testing (radiated or conducted immunity) to help determine the immunity characteristics of your circuits or product.
1. Chattering Relay (120VAC powered) – can produce strong broadband emissions all the way out to at least 1 GHz.
2. 3 VDC Motor – produces strong emissions out to about 750 MHz.
3. Pocket Plasma – produces broadband frequencies up to 10 MHz.
Click here for more details…
I had a chance to visit Com-Power Com-Power (http://www.com-power.com) 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.
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.
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.
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…
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…