Last week, I wrote a blog post on preventive maintenance for one of my writing clients.
Afterwards, I decided to take some of my own medicine and do a little preventive maintenance around the shack. I started with the Astron RS-35M, which provides the DC power that runs HF transceiver and my VHF/UHF transceiver in my shack. I had started noticing a few little things, such as the voltage adjustment being a little fussy, that I wanted to correct before the supply failed on me.
After removing the cover, I vacuumed all the dust out of the supply. The RS-35M wasn’t very dirty, but even so, getting the dirt out of a piece of equipment is probably the first thing you’ll want to do when performing preventive maintenance. Dirt impedes air flow. That can lead to higher operating temperatures, and as the lab manager that I interviewed for my blog post said, “Heat kills.”
Not only should you vacuum any dust out of a cabinet, you should also clean the fan filters, if your gear has them. Dusty filters prevent air from flowing smoothly through equipment, and that means the fans don’t cool as well as they should.
Once that was done, I did a visual inspection. One thing that you want to look for are components that look like they’re getting too hot. Another thing to look for is evidence of arcing. Whatever is causing the overheating or arcing will eventually cause a unit to fail. Fortunately, I found neither.
Next, I checked to see that the components mounted to the enclosure were securely screwed down. In the RS-35M, the transformer, the bridge rectifier, and an electrolytic are mounted to the enclosure. Oddly enough, the bridge rectifier was quite loose, so I tightened it down. Also loose were the output terminals. I tightened these down as well.
Finally, I squirted a little cleaner and lube into the voltage adjustment pot and worked it back and forth. That seemed to do the job. That pot now works smoothly and cleanly.
I put the cover back on, reconnected the power cable, and got back to making QSOs. It should be good for another couple of years.
Volunteer storm spotters essential to Weather Service. The haunting companions to tornadoes and major thunderstorms make children cry, grown men run into basements and auto dealership owners cringe. But some people embrace the danger and even seek it out for entertainment. Among this group are Skywarn storm spotters, volunteers who work with the National Weather Service to track and report storms from the front lines.
Making tubes again. Western Electric has been resurrected, and its headquarters are in Rossville, GA. A once-vacant bank building was adorned about three weeks ago with distinctive red-lettered “Western Electric” signs on its east and west sides. The Rossville operation will make vacuum tubes mainly for use in high-end audio components. “It’s a lost art,” company president Charles G. Whitener Jr. said.
Ham radio — a pastime not just in the past. With today’s advanced wireless technology, amateur radio might have become obsolete. Yet, it hasn’t. Did you know the first “chat room” was invented by ham radio operators? They communicated across the continents during wartime, and played chess all hours of the day and night. And amateur radio invented social networking. Amateurs are viewed as public servants and a national resource. It doesn’t look like these guys are going away anytime soon.
Ham operators’ paradise at Friedrichshafen’s flea market. Over a week ago I attended the Ham Radio show in Friedrichshafen, Germany. This is the biggest ham radio show in Europe and has the usual big-convention mix of commercial exhibitors, national society exhibits, conference-style forums, and… a flea market.
From the 7/10/13 issue of NIST Tech Beat….Dan
Despite warnings to the contrary, many people continue to operate portable generators indoors or close to open windows, doors, or vents, resulting in more than 500 deaths since 2005. And each year, more than 20,000 people visit the emergency room and more than 4,000 are hospitalized due to exposure to toxic levels of carbon monoxide (CO), a colorless, odorless gas. Fatality is highest among people 65 and older.
A new computer modeling study* by National Institute of Standards and Technology (NIST) researchers scrutinizes the deadly relationship between CO emissions and occupant exposure. They conducted simulations of 87 types of dwellings representative of the U.S. housing stock with a generator operating within a room in the house, its basement, or attached garage.
The study considered two scenarios of portable-generator operation: continuous operation for 18 hours and operation with some type of control technology that causes the generator to shut off periodically, or so-called “burst” releases.
Regardless of housing type or location, generators that release as little as 27 grams of CO per hour continuously for 18 hours cause 80 percent of the modeled cases to result in an exposure predicted to reach dangerous levels. In comparison, current commercially available generators that were tested by NIST in a previous study emitted CO at a rate of 500 to 4,000 grams per hour.**
For generators characterized by burst releases of CO, the NIST team found that CO emissions of more than 139 grams resulted in dangerous levels of exposure.
The findings, reported to the U.S. Consumer Product Safety Commission, could help in setting limits on CO emissions from portable generators.
*A.K. Persily, Y. Wang, B.J. Polidoro and S J. Emmerich, Residential Carbon Monoxide Exposure due to Indoor Generator Operation: Effects of Source Location and Emission Rate (NIST Technical Note 1782), June 2013. Downloadable from:www.nist.gov/manuscript-publication-search.cfm?pub_id=912394.
**S.J. Emmerich, A.K. Persily and L. Wang, Modeling and Measuring the Effects of Portable Gasoline Powered Generator Exhaust on Indoor Carbon Monoxide Level (NIST Technical Note 1781), Feb 2013.
This looks kind of cool, even though I’ve still not really done anything with the Arduino I built several years ago.
Apparently, Dr. Richard Crane, the original W8CWN, encouraged his students to tinker.
While it’s nice to see them commemorating Morse Code, the code on the chart is the International Code. What they would have used in 1844 in the United States is American Morse.
Photo and info hanging in our hotel lobby pic.twitter.com/PIFSQzq9jr
Here are a few more links to SDR for amateur radio. I really gotta start building that SoftRock so that I can then tackle some of the more complex projects…..Dan
Elad FDM Duo SDR transceiver can be used with a computer or stand-alone. This little transceiver was demoed recently at the Ham Radio Fair in Friedricshafen, Germany. The Elad On-Line Shop does not yet list a price for this radio yet.
A $40 Software-Defined Radio. This article on SDR hacking from IEEE Spectrum mentions amateur radio.
A recent news story about the 50th anniversary of WWVB got me to thinking about building my own WWVB receiver. I Googled “wwvb kits” and came up with the following:
- WWVB NIST Radio Time Receiver Kit
- WWVB Chiming Clock Kit
- WWVB 60 kHz Time Receiver Module with Antenna
Unfortunately, all of these kits use a little PC board made by a company called C-MAX, and the company has either discontinued making the IC that powers this module or simply quit selling this module in the U.S. As recently as a couple of years ago, Digikey actually sold this module for about seven bucks.
There are several Web pages that show how to interface the CMMR-6 module to an Arduino or a PIC processor. Here are two:
A couple of companies in the UK seem to still have the modules in stock. The price from a company called Earthshine is only six pounds, but that doesn’t include shipping, of course.
There are some plans that don’t use the C-MAX chip, but, of course, they’re much more complex. One guy designed his own receiver, but it’s quite a bit more complex than simply using a single chip. There are also several commercial receivers available, but the cheapest one I found is $220.
There are several Web pages that describe how to use the WWVB receiver modules from “atomic clocks.” One of the projects scavenges the WWVB module from a Sony clock. The second uses the module from an Atomix 13131. The Atomix 13131 costs as little as $13.
So, I’m still unsure which way I’m going to go here, but it looks as though hacking an existing clock might be the way to go, especially if I can find one at a thrift shop or garage sale.
Another selection of amateur radio related items appearing recently in the electronic engineering trade publications.
Litz wire and other component cleverness
If you’re not familiar with it, litz wire is not named after a person or a place. It’s short for Litzendraht, the German term for braided, stranded, or woven wire. It’s a very clever solution to the problems and inefficiencies caused by the skin effect — as the frequency of the current that a wire carries increases, the current tends to go to the outside of the wire.
Vector network analyzers support versatile testing
Among the most valuable of RF/microwave test tools is the vector network analyzer (VNA), which can measure amplitude and phase with frequency. VNAs have long become associated with the measurements of complex impedance parameters—such as scattering (S) parameters—using the test data to design efficient impedance matching networks for the optimum transmission of high-frequency signals through active and passive devices and networks. At present, VNAs are available from both well-known and not-so-well-known instrument manufacturers, in both bench top and portable configurations for making measurements on high-frequency (HF) through millimeter-wave-frequency signals.
Integrated RF analog, multi-standard, software-defined radio receivers
The scaling of CMOS technologies typically has a great impact on analog design. The most severe consequence is the reduction of the voltage supply. Imec and Renesas have managed to put a complete, high-performance SDR (Software Defined Radio) receiver into a 28nm CMOS process with a 0.9V power supply. The IC has everything except a PLL on a single monolithic chip. (See Figure 1.) This is an impressive integration of analog functionality.
Interesting stuff on Twitter this morning…….Dan