Category Archives: Troubleshooting

Questions on Radiated Emissions Pre-Compliance Testing

Following the recent webinar sponsored by Rohde & Schwarz, I received way too many questions to answer during the live presentation, so I’m following up gradually and posting my answers on The EMC Blog, now hosted by EDN.com.

I just posted my third article:

3. Questions on EMC pre-compliance testing for radiated emissions

I’ll be posting one more on the questions I received on general EMC topics some time in August.

In the meantime, I’ll be attending Doug Smith’s ESD/EMC three-day seminar next week and may write up a description with pictures. The week after that, I’ll be attending the annual International Symposium on EMC right here in Denver. I’ll be posting at least two articles on new products and other activities.

Presentation during the IEEE EMC Symposium

I’ve been invited to be the keynote speaker at the annual NEC EMIStream evening seminar and reception during the IEEE International Symposium on EMC, Thursday, August 8th, from 5:30 to 7:00 PM. The title of my presentation is “EMC Troubleshooting and Pre-Compliance Testing on a Budget”. For more details and to register for this free event, check out this link. http://www.nec.com/en/global/prod/emistream/ieee_seminar2013.html

R&S Webinar, June 20, 2013

My first EMC webinar hosted by Rohde & Schwarz went off pretty well last Thursday, with 276 attendees from around the world checking in. Thanks to all for listening to some of the most common EMC issues I deal with during my consulting.

There were a number of questions asked, that I wasn’t able to get to due to lack of time, however, Rohde & Schwarz will be providing a list of the unanswered questions early next week and I intend to group like ones together and answer these periodically via this blog. Some of the more interesting questions will be answered on The EMC Blog, hosted by Test & Measurement World.

Thanks again for all who attended. I suspect we’ll do this again some time.

A pocket-sized 5.35 GHz USB spectrum analyzer!

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.

IMG_1482Figure 1 – Photo showing the analyzer with supplied USB extension cable and 30 dB attenuator.

16 MHz Osc with Mkr-600Figure 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…

Milwaukee EMC Mini-Symposium – March 2013

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!

P3190643BlahaIntroJim Blaha from GE Medical manages the symposium and is providing introductory comments.

P3190408KenNcrowdDemoTableChatting during one of the breaks.

P3190645ClassAudienceA portion of the 180 attendees.

P3190675KenPigtailNspectrumHere I am explaining why pigtail shield connections cause common-mode currents resulting in radiated emissions.

P3190677RoomFrom BackA very full house!

EMC Troubleshooting Parts Storage

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.

IMG_1431

 

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…

 

Unusual EMI Sources

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.

IMG_1423

2. 3 VDC Motor – produces strong emissions out to about 750 MHz.

3V Motor 1

3. Pocket Plasma – produces broadband frequencies up to 10 MHz.

IMG_1419

Click here for more details…