What are your favorite hardware tools that you use?

Well, since I am no longer working in a corporate lab environment anymore, I am left with a personal oscilloscope, DC power supply, DMM, and logic probe. They satisfy most of my tinkering needs. Back in my “working” days, spectrum and network analyzers, signal generators, and power meters were part of the daily diet. I keep telling myself I need to buy more equipment (used, of course), but that will have to wait until I have more time to use it.

What are your favorite software tools that you use?

For the last few years, web authoring software (MS Expression Web), Excel, Visio, and some graphics tools are about it. Occasionally I need to use a circuit simulator so I’ll go download the newest version of a demo and do what I need that way. Honestly, I have not used a lot of simulation tools during my career. Most of the time I create my own spreadsheets to accomplish what needs to be done, particularly for system level stuff. Almost all my design work has been at the PCB and connectorized component level where space was not critical (i.e., not too much worry about cross-talk between signal layers, shield wall proximity effects, etc.), so simulators would not have added a lot of advantage. What I would really like is to have time to re-write my RF Workbench system simulator software to work in Windows. I’ve been threatening to do that for almost two decades. Maybe next year…right.

What is the hardest/trickiest bug you have ever fixed?

This one goes back quite a ways to when I was hired to work on a re-design for part of a remote, automated meter reading system. The transmitter portion (around 20 W in the 900 MHz ISM band) was to remain basically unchanged except for that it exhibited a very random spurious output that had eluded a solution by the company’s top engineers. Those guys were such good engineers that it was almost intimidating to even be assigned the task of getting to the root of the problem. Between the engineers and the technicians, much effort had been expended trying to track down the gremlin. The good thing about stepping into the frying pan with all eyes on you is that all of the obvious solutions had already been tried, so I did not have to waste time with various bypass capacitors, tighter tolerance components, shielding, layout, etc. As luck would have it, I could not quite understand why the supply rail for the positive was configured in such a way that it moved up and down with the modulation signal at the input. The designers were very experienced commercial radio guys, and I figured the scheme was de rigueur for those in-the-know. So, rather than embarrass myself, I decided to replace the amplifier supply circuit with a fixed DC voltage. Voila! Problem instantly solved. No matter how much we heated or cooled or how the modulation changed, the spurs were gone for good. I also instantly had a whole new problem – how would I report the find without totally infuriating the other engineers who had wrestled in vain toward the same end result? A carefully written report to management that was sure to laud the efforts of others who paved the way for my success seemed to do the job. My remaining time at the company went very well, especially with the production line technicians who had endured a lot of heartache in trying to get the transmitters to pass test. I don’t want to mention the company name, but suffice it to say they are still one of the world’s top AMR system producers.

What is on your bookshelf?

My book shelf undergoes a continual refreshing of engineering and science titles because most of the books I acquire end up being given away in the monthly RF Cafe Book Contest (47 so far). A few books are stalwarts that will never leave me, like engineering references and a handful of RF system design tomes. Other than that, I do have some biographies on Charles Schulz (Peanuts) and many model airplane magazines. Every month I read through as many as 15-20 magazines including Scientific American, Sky & Telescope, Smithsonian, Inc, Discover, Popular Science, Birds & Blooms, Handyman, Strings, and QST as well as all the major RF engineering publications. If you are a regular visitor to RF Cafe, you will see that probably half the fodder for my writings stem from subjects read in those magazines.

Do you have any tricks up your sleeve? (special way to analyze circuits, special process you use to make something, etc)

Having begun my electronics career as a USAF radar technician, I learned a lot of troubleshooting strategies before ever entering the engineering realm. One instrument that I think is underutilized when troubleshooting circuit boards is the multimeter. If you understand circuit theory, making DC bias measurements around the board can uncover a lot of problems that might be hard to find with just an oscilloscope. Sometimes watching a waveform rather than the DC operating point can blind you to the real problem. Troubleshooting a large production lot of boards can really benefit from this approach. For RF work, it’s hard to imagine life without a sniffer probe – usually a homemade job constructed from a piece of semi-rigid coax cable. Solder a small high frequency capacitor in series with the tip for direct probing without loading the circuit too much, or form a small loop from the center conductor to ground for inductive sniffing. None of this is anything that I thought up on my own, but I’ve been amazed at the number of people who have never tired it until it is suggested.

What has been your favorite project?

No single project stands out as much better than the rest. Most have had their unique challenges that required late nights and weekends to get through – ah the privilege of being a “professional” and not getting paid for overtime! Now, as for my favorite job, it was undoubtedly while working as an RF applications engineer at the last company before doing RF Cafe full-time. My job was more that of a reverse engineer than an engineer. Most of the time was spent tearing down competitors’ products and writing reports on what I discovered. It involved everything from etching away ICs and mapping out circuits to x-raying and photographing layers of ceramic substrates, as well as the more mundane task of creating parts lists by some creative component identification methods. You might be surprised at the amount of information that can be publically accessed just by starting with a known website path and trying similar URLs until you hit a document that is on the public server, but is never linked to by the company. I really worried our IT department occasionally with some of the suspicious Russian and Chinese websites that I would visit (with anti-virus and firewall running at full strength) to download complete schematics of new model cellphones and other wireless devices. Most of that documentation was normally reserved for service centers and customers with special access. However, it was all accessible without breaching any protected media. The Internet is a wonderful place.

Do you have any note worthy engineering experiences? (blowing up things, getting shocked, etc)

Hmmm. The only good shock I can remember getting is from a high voltage CRT supply from one of the precision approach radar displays whilst in the USAF. I’ve been pretty cautious around dangerous circuits ever since then. Oh, wait, I do have a good story to tell. Back at that AMR company, one other engineer and I had to take the newly designed system to a test area where the read rate on the installed meter base had gotten really poor because of an increase in the urban electrical noise environment. That area turned out to be the heart of Chicago. Great. The original read rate was something like 98% at a speed of 30 mph. Over a span of a few years, it had dropped to about 90-92%. Part of the test route was in an area so riddled with crime that the power company had to hire off-duty policemen to read the meter that our RF equipment could not read, so it was imperative that the number be moved back up to near 98%. The transponder was mounted in an unmarked, black minivan that had a 1/4-wave whip antenna mounted on the top, and curtains on the windows to keep prying eyes away. For three days, two lily white guys drove that van, which looked like an undercover law enforcement vehicle, through some of the roughest inner city neighborhoods we had ever seen. The advice from the power company engineer to only stop when absolutely necessary – even at intersections – was heeded. All eyes from the street were on us every time we travelled the route. Once, our van got trapped in an alley for about ten minutes between two other trucks that had stopped to make deliveries; that really got the hearts racing! We nervously laughed our way through the days as we listened to the AMR transponder sound off with a continuous stream of beeps each time a successful read was made. I don’t recall the exact number, but the read rate was back up high enough to make the power company guys happy, and that meant we wouldn’t have to go back to do it again! Remind me some day to tell you the story about the homeless guy and the smoking grocery cart…

Notes on Kirt’s Photo…

Here is where the RF Cafe magic happens ;-) Charlie Brown keeps watch over the operations, while Dilbert supplies an M&Ms fix as required. The model airplane engines are ones I had as a kid – defined as the period beginning around 1968 (age 10) and running through 2010 (age 52). My computer is an HP desktop (which is a misnomer since none have sat on top of a desk since the Packard Bell 286 era) with a 22” Gateway LCD monitor. A partial paralysis in my right index finger makes using the mouse on the left side a necessity. Oh, and in case anyone is wondering, that’s a “Moe for President” T-shirt; I’d take him over any politician in the last 20 years.

Visit Kirt’s RF Cafe Website