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Tech Topics Smorgasbord Archives - 36

RF Cafe University"Factoids," "Kirt's Cogitations," and "Tech Topics Smorgasbord" are all manifestations of my rantings on various subjects relevant (usually) to the overall RF Cafe theme. All may be accessed on these pages:

 1 | 2 | 3 | 4 | 5 | 6 | 7 | 8 | 9 | 10 | 11 | 12 | 13 | 14 | 15 | 16 | 17 | 18 | 19 | 20 | 21 | 22 | 23 | 24 | 25 | 26 | 27 | 28 | 29 | 30 | 31 | 32 | 33 | 34 | 35 | 36

ChatGPT: Inaccuracies in Technical Responses

ChatGPT: Inaccuracies in Technical Responses, Kirt's Cogitations #351 - RF CafeSince January, I have used ChatGPT to generate many mini essays on various technical topics such as company histories, biographies on notable engineers and scientists, physics principles, and industry standards. My goal is to reduce the amount of references to off-site information like Wikipedia. A careful reading of ChatGPTs replies is always performed because inaccuracies appear fairly often. Overall, I find it very useful, but caution is needed. In example, today I queried ChatGPT for an equation of the voltage distribution along a half-wave dipole antenna. It took three rounds of correcting its response to finally get an accurate answer...

Odes on Technology

Poems Odes on Technology, Kirt's Cogitations #351 - RF CafeOpenAI (ChatGPT) founder Greg Brockman, recently produced a video introducing some of the improvements and new features of GPT−4 (current public version is GPT−3.5). One thing he did was have the AI machine asked it for a single sentence summary using only words beginning with the letter "g." GPT−3.5 failed miserably, but GPT−4 succeeded. It even did a sentence using only words beginning with the letter "q." He also had GPT−4 create a poem about the tax preparation capability of ChatGPT (itself an impressive act). A few of the vintage issues of Popular Electronics and the ARRL's monthly QST magazine contained electronics-related poems submitted by readers (see "Unpopular Radio," and "Pre-Radio," et al). Some are pretty clever. It takes some cogitation, skill, and creative ability to come up with a rhyming poem on a technical subject like amateur radio. Since I am in insufficient possession of the aforementioned qualities, I decided to task ChatGPT to create a few topical poems for me. Is this amazing, or what? Be sure to see "Ode on Rhode & Schwarz" and...

Noise Figure / Y-Factor Conundrum - Solved

Noise Figure / Y-Factor Disagreement Conundrum - Solved, Kirt's Cogitations #350 - RF CafeWebsite visitor Jared Finan contacted me a few days ago to ask whether I had any idea why noise figure and Y−factor measurements made with his HP/Agilent/Keysight 8975A Noise Figure Meter were not in agreement. The same measurements made with his HP/Agilent/Keysight 8970A - a much older piece of equipment - agreed very well. My suggestion turned out to not be the answer. Jared wrote back later saying he found the cause of the problem - a real exercise in troubleshooting! He gave his permission to post our dialog here so in case someone else might have been plagued with a similar issue. There are several methods for measuring noise figure, including the Y-factor method, the cold source method, and the hot/cold load method. The Y-factor method is the most widely used technique for noise figure measurement...

Mystery Burst Transmission in the HF Ham Bands

Mystery Burst Transmission in the HF Ham Bands, Kirt's Cogitations #349 - RF CafeA couple days ago, website visitor Bill P. wrote from his location in the western mountains of North Carolina to ask whether I have any information on a mysterious burst transmission he has been picking up in the 10− and 12−meter bands (28.000 to 29.700 MHz and 24.920 to 24.930 MHz, respectively) that "only appears when the bands are open." The signal has appeared intermittently for more than ten years. He included a link to a demodulated audio file of the captured signal. It sounds like a series of bursts at the same frequency. I do not recall ever having heard it. Probably the best method for determining the source of a broadcast is to perform a spectral analysis of the demodulated signal to discover its constituent parts. I used a free audio analyzer package called WavePad, by NCH Software. The screen shot below quantifies a few of the primary parameters. It consists of 63 bursts at approximately 24 ms intervals. Each burst appears to be a CW signal of about 1,280 Hz (780 μS), although looking at the spectral waterfall most of the content appears to be in 1,100 Hz realm...

Some Thoughts on the Balloon Fiasco

Chinese Spy Balloon Fiasco, Kirt's Cogitations #348 - RF CafeLike a lot of Americans (and presumably some Canadians), I was amazed to watch as a Chinese spy craft as large as a couple school busses was permitted to drift over the country from Alaska to South Carolina. It was laden with sophisticated sensors (optical?, radio frequency?, audio?) and communications equipment, powered by huge PV arrays. A detailed reverse engineering effort of an intact, possibly functional inspection could determine the system architecture, electronic component types, software / firmware, mechanics, optics, battery technology, etc., including where they came from and who built them. A lot of information can be gleaned from such an investigation. We are just now being informed that the military knew of the craft from the time it was launched off the coast of China. We are also now told that Biden* was not apprised of the situation until it had been spotted over Montana by civilians and photographed with a cellphone. Then, officials said bringing it down over populated areas was too risky, even though there was ample opportunity to do so while it was over unpopulated areas in Alaska and Canada. In fact, it could probably have been brought down over land gradually via controlled deflation rather than blowing it out of the sky with a Sidewinder missile. The payload equipment would then have been more readily accessible and intact for inspection. Prior learning the balloon was being tracked even before it flew over the U.S., we were told that NORAD and all other radars missed it...

"ChatGPT: OpenAI Content Generation

ChatGPT: OpenAI Content Generation, Kirt's Cogitations #347 - RF CafeSince its launching on November 30 of last year (2022), I have seen / heard a lot of news reports about the ChatGPT content generator hosted by OpenAI.org. They label it a "chatbot." The GPT suffix is an acronym for Generative Pre-Trained Transformer. ChatGPT is an artificial intelligence (AI) algorithm that creates a paragraph or two about a topic which you enter in the webpage. Proponents hail it as one of the first instances of making AI available to the public, and facilitate information search and dissemination. Opponents warn that ChatGPT is a scheme which can feed on its own self-generated inaccuracies when generated content is posted online and used later by the same algorithm. One aspect that occurred to me whilst experimenting with ChatGPT is that while you are helping to train the AI algorithm, it is simultaneously training you to communicate effectively with it, so it's a two-way process. Sometimes it takes many iterations of a query to get the preferred results. Note that sometimes ChatGPT server is so inundated with participants that you might need to submit your query multiple times to get any result other than an error message. Feedback can be provided to ChatGPT regarding the usefulness of its reply by clicking on the up or down thumb icons. I could go into a little more detail about ChatGPT, but why not let the chatbot extoll its own virtues...

Milestones in U.S. Patenting

USPTO Timeline: Milestones in Patents - RF CafeThe USPTO, issued its first patent on July 31, 1790, assigned to Mr. Samuel Hopkins for a process of making potash. That was three years after creation of the office in 1787. President George Washington signed that one. You might think the country's first issued patent is numbered one (later designated X000001), but that's not the case. Enumeration did not begin until July 13, 1836 when U.S. patent "No 1" was issued to Mr. John Ruggles for a traction wheel for steam locomotives. The U.S. government had issued 9,957 patents before starting a numbering system so for any patent number, add 9,957 for its actual place in line. The one millionth patent was assigned in 1811. #2,000,000 happened in 1935. The ten millionth patent was issued in 2018 for coherent ladar using quadrature detection. #11,000,000 was awarded just three years later. By process of elimination, I found that as of this very moment (10:30 am EST, December 27, 2022), the highest patent number assigned per the USPTO's website is #11,540,433..

QST Spotlight: Dr. Joseph Hooton Taylor, Jr., K1JT

QST Member Spotlight 2023: Dr. Joseph Hooton Taylor, Jr., K1JT - RF CafeThe January 2023 issue of QST magazine highlights Dr. Joseph Hooton Taylor, Jr., K1JT. An accomplished radio astronomer, Dr. Taylor's feature is the first of what will be a year-long theme to "highlight amateurs who have achieved recognition in areas outside of, or related to, amateur radio." I think that is a great idea and look forward to seeing who they come up with. Too bad that the ARRL doesn't post stories like this so that non-members can have access to them; they would serve as a great motivation to people considering earning a new license or upgrading to a higher class. "JT. Since 2001, those two letters have signaled digital transformation in ham radio. They are the initials of the pioneering scientist and amateur radio innovator, Joe Taylor, whose software suite, WSJT - updated to WSJT−X - revolutionized ham radio. Today, the warble of JT8 dominates, but the tones of FT4, JT9, SWPR, and Q65 all emerge from the static to connect hams the world over with signal-to-noise ratios as low as −44 dB..."

Engineering Website Traffic Summary: 2022

Engineering Website Traffic Summary: 2022 (SEMRush.com) - RF CafeAs a rule, I do not spend much time wondering what other engineering websites are doing or what their visitor traffic might be. Instead, I spend my time creating a format and content that caters to the needs of RF Cafe visitors - engineers, technicians, students, hobbyists, researchers, etc. I do not use pop-up windows for ads, announcements, cookie warnings, or anything else. I have never betrayed the trust of visitors by selling or trading their IP addresses, e-mail addresses, or any sort of statistical data. Doing so is rewarded with a good flow of website traffic. The graphs are screen captures from the SEMRush webpage. The results were a bit surprising in some instances, but expected in others. For reference, RF Cafe gets an average of 29,539 "organic traffic"/month. By comparison, the IEEE website has 2,879,641/month (97x more). The ARRL website sees 146,616/month (49x). Microwave Journal is at 5,916/month (1/5th). Microwaves & RF shows 9,366/month (1/3rd). Two what might be considered competitor websites, everythingRF and Microwaves101, are at 164,110/month (5x) and 24,750/month (7/8ths)...

Electronics Companies' Magazine Ads

Electronics Companies Magazine Ads August 2022 Microwave Journal) - RF CafeIt has been my belief for a long time that the vast majority of print magazine advertisements are never seen by potential customers because very few of those potential customers ever bother to pick up a print magazine. More than a decade ago (around 2007) when I was spending my last days working in a corporate environment, I do not ever recall seeing anyone reading a trade magazine, be it Microwave Journal, Microwaves & RF, Electronic Design, EE|Times, or any of the others. In fact, most of the magazines I saw were deposited in the mail room recycle or trash bin before they ever made it to an engineer's, technician's, or manager's desk. That is not to say or imply the magazines are not excellent - they are, indeed - but even back then most people were getting their needed information online. Being able to show a print version circulation number to advertisers does not in any way correlate directly to the number of potential customers who will ever see their advertisements...

FITSAT-1 CubeSat Flight over Erie, PA

FITSAT-1 CubeSat Flight over Erie, Pennsylvania - December 12, 2012 - RF CafeI stayed up late on the night of of December 11, 2012 (early in the morning, actually) to watch the FITSAT-1 CubeSat satellite flash its Morse code "HI DE NIWAKA JAPAN" message via super-bright LEDs over eastern North America. It was scheduled to pass just south of my location in Erie, Pennsylvania, at 1:14 AM, with a lights-on intensity great enough to be easily seen with binoculars. FITSAT-1 is a project conceived of and built by professors and students at the Fukuoka Institute of Technology (FIT) in Japan. In addition to the LED visual display, the satellite also carries several Amateur Radio payloads including a CW beacon on 437.250 MHz, a telemetry beacon on 437.445 MHz and a high-speed data downlink on 5,840.0 MHz. The CubeSat Project was developed by California Polytechnic State University and Stanford University's Space Systems Development Lab. It creates launch opportunities for universities previously unable to access space. A CubeSat is 10 cm on a side and may have a mass of up to 1.33 kg. Launch vehicles sell space to CubeSats for around $40,000, which makes them very affordable to place in orbit...

Electronics Companies' Magazine Ads

Electronics Companies Magazine Ads (July 2022 Microwave Journal) - RF CafeIt has been my belief for a long time that the vast majority of print magazine advertisements are never seen by potential customers because very few of those potential customers ever bother to pick up a print magazine. More than a decade ago (around 2007) when I was spending my last days working in a corporate environment, I do not ever recall seeing anyone reading a trade magazine, be it Microwave Journal, Microwaves & RF, Electronic Design, EE|Times, or any of the others. In fact, most of the magazines I saw were deposited in the mail room recycle or trash bin before they ever made it to an engineer's, technician's, or manager's desk. That is not to say or imply the magazines are not excellent - they are, indeed - but even back then most people were getting their needed information online. Being able to show a print version circulation number to advertisers does not in any way correlate directly to the number of potential customers who will ever see their advertisements...

My Bifurcated Spinal Cord

My Bifurcated Spinal Cord (Kirt Blattenberger) - RF CafeIn 2012, while moving a heavy safe down some stairs (using a hand truck), something snapped in my lower back that resulted in debilitating leg pain for a month. Hydrocodone was required to enable normal locomotion around the house, and I couldn't lift anything. After about three months, things returned to normal, with occasional relapses. Since that time, I have tried to be careful to not overexert myself, and kept up a regular regime of isometric and low weight, low impact exercise. Maintaining muscle tone is essential for keeping the skeleton in proper alignment. As time went on, I became a little bolder in terms of lifting, pushing, and pulling heavy objects, and got away with it until early March of this year when I foolishly used a long pry bar to tip over a huge tree stump. The stump finally broke loose, and so did my back. This time, the pain was so bad that I couldn't walk more than a couple feet without needing to recover, and finding a comfortable position to relieve the hurt was nearly impossible. Even the 5 mg hydrocodone barely touched it; at least two were required. I have always avoided taking any sort of medicine, even ibuprofen or acetaminophen, so at trip to a back surgeon† ensued. An x-ray showed a few bone spurs on some of the vertebrae impinging on my spinal cord, but nothing deemed severe enough to cause the level of pain I was experiencing. I think my doctor though I was exaggerating, so I requested that he order an MRI...

Carl Kohler's Life & Times per Son, Christoverre 

Carl Kohler's Life & Times per Son, Christoverre - RF CafeAs mentioned in the past, one of the many great aspects of the Internet, and in particular having a website with its contents easily found on a search engine, is occasionally being contacted by people mentioned in one of the vintage magazine articles I have posted on RFCafe.com and AirplanesAndRockets.com, and/or by people related to someone mentioned. Readers of Popular Electronics magazine in the 1950's through 1970's (including me) looked forward to Carl Kohler's many humorous electronics-related stories and illustrations a few times each year. Carl's leading man was one print media's first DIYers, and his wife suffered his often less than successful escapades in a sporting manner. A few days ago, none other than Christoverre Kohler, Mr. and Mrs. Carl and Sylvia Kohler's number two son (of four), contacted me to provide some background on his parents. Christoverre happened upon a couple of his father's articles on RF Cafe while doing a search. He was motivated to write in response to the story entitled, "I Married a Superheterodyne!," where I asked whether the Kohlers might have at one time lived in Syracuse, New York. It was due to a mention of General Electric's famous Electronics Park (which is no more). Christoverre set me straight on that matter, and provided some amazing additional information on his parents. His father's talents were not limited...

Kazakhstan Broadcast Facility in Balkhash

Kazakhstan Broadcast Facility in Balkhash - RF CafeRF Cafe visitor Jonathan Zane (KC2SHO) recently sent me a hyperlink to his collection of photos taken when he visited a broadcast facility in Balkhash, Kazakhstan. A sample of his extensive image cache is shown here. You can view the entire set that includes vintage electronic equipment, facilities, and city streets on his kc2sho.com website. You will see a huge stash of vacuum tube assemblies, large coaxial cables, operation and maintenance manuals, and spare parts. These kinds of treasure troves exist all over the world; it's a matter of finding them. Imagine what all that abandoned equipment and components would sell for on eBay! Along with requesting permission to post a few of his photos, I invited him to provide some text to accompany them. Here is what he wrote - you will definitely like the anecdote at the end. Many thanks to Jonathan for this!

Astrometry.com Plate-Solving Star Identifier

Astrometry.com Plate-Solving Star Identifier - RF CafeThe term "plate solving" (aka "astrometric solving") in astronomy has its roots in the days when dinosaurs roamed the earth and images of the sky were captured on, gasp, glass plates with photosensitive emulsion coatings. Attempting to identify astronomical items on a plate, or paper photograph developed from a plate, was/is similar to finding an unfamiliar star, nebula, or galaxy when viewing the heavens through binoculars or a telescope. You begin with a nearby entity you are familiar with, and then move in the direction of the object being sought. Sometimes a process known as "star hopping" is used to move from point to point in a predictable combination of direction and distance from the current star (or whatever). With the advent of digital photography, software programmers have developed algorithms that assess and map all the points an image, then compare it to a calibrated set of points from carefully processed images and attempt to identify all the astronomical object in the investigated image. Only fairly recently has a highly efficient method of computer plate solving been available. Fortunately, the community of professional and amateur astronomers has produced a plethora of software tools...

The XML Guts of an Excel Workbook File

The XML Guts of an Excel Workbook File - RF Cafe SmorgasbordSome years ago while first developing my "RF Cascade Workbook" spreadsheets, I read that when Microsoft began using the XML file format for Excel with the 2007 version (Office 12), what appears in the File Manager as a *.xls or *.xlsm (*.xls with VBA‡ macros) is actually a compressed collection of individual XML files and possibly a *.bin and any images you might have buried within. If you want to see what actually makes up your Excel file, follow these simple instructions. A word of warning though, as Otto von Bismarck is reported to have admonished†, "Laws are like sausages. It is better not to see them being made." After seeing what goes into an Excel file, you might loose your taste for them (not really, it just seemed like an apt quotation at the moment). There may be another way to dissect an Excel file, but probably the easiest is the following...

Eyes of a Generation™... Television's Living History

Eyes of a Generation™... Television's Living History - RF Cafe SmorgasbordIf ever there was a website that would likely drag a radio and television broadcast historian down into the metaphorical rabbit hole, "Eyes of a Generation... Television's Living History" is it. Like Alice's experience in Wonderland, once you enter the homepage porthole and begin clicking on links, not only will getting back out be difficult, but the journey will introduce you to many fantastic experiences in TV broadcasting which you have never seen before. As the subtitle says, "In essence, this is a Television history book with 5000 stories, 10,000 rare photos and hundreds of one of a kind videos." If you are old enough to remember way back to the 1980s and before, then you will find interesting tidbits of insider and backstage anecdotes about all of the popular television shows of the various eras - back to the very beginning. That includes sitcom, variety, and news types. Included in the collection is a wealth of photographs and videos, along with histories of the electronic equipment and its inventors that made it all possible. You will also find never-seen-before film footage of live taping sessions, TV show production, interviews, and documentaries. Did you know that David Letterman owned the entire "Late Night" franchise...

Bob Pease's Messy Workbench in CQ Magazine #335

Smorgasbord: Bob Pease's Messy Workbench in December 2021 CQ Magazine (Eric  Nichols) - RF CafeCQ magazine is a great monthly publication for the electronics hobbyist and professional. Each month it is chock full of amazingly informative articles covering circuit design, system design, antenna design, product reviews, electronics theory, prototyping and kit building, industry news, and more. Being primarily an amateur radio publication, CQ also contains many pieces on equipment setup and use, operational suggestions, contest coverage, ARRL events, FCC regulatory news, reports on personal accomplishments, etc. As part of his "Haywire State" article, Eric highlights the venerable Bob Pease (sadly no longer with us) with his famously messy workbench and tangle breadboarded circuits...

The Letter "Xi" Stricken from Greek Alphabet #334

WHO skips Xi COVID-19 variant going from Nu to Omicron - RF CafeThis gives a whole new meaning to "Political Science." Vaccinated people have been generating and shedding copious variants of COVID−19. WHO designates each new variant with progressive letters in the Greek alphabet, beginning with Alpha. Until a few days ago they were on Nu. Next came Omicron. "What happened to Xi?" you might reasonably ask. It so happens that Xi (Jinping) is the name of China's dictator, so "the Science" we are admonished to listen to omit it. Now we need the Ministry of Truth to replace all former references to Xi (Ξ, ξ) with some other symbol. Let me be the first to suggest a spiked virus icon Coronavirus Icon - RF Cafe. Damping ratio henceforth is written as Coronavirus Icon - RF Cafe = 2.5 rather than the traditional ξ=2.5. Similarly there is the Coronavirus Icon - RF Cafe baryon (rather than the Xi baryon), the Riemann Coronavirus Icon - RF Cafe function, potential difference is Coronavirus Icon - RF Cafe volts, the Scientific Research Honor Society is now Sigma Coronavirus Icon - RF Cafe. You get the idea...

Electronics Themed ASCII Art #333

Electronics Themed ASCII Art - RF Cafe SmorgasbordASCII Art has been around nearly as long as digital computers have been in existence. It was the only type of "graphics" available to most users before other than text displays were commonplace. Universities, corporations, and government research facilities had crude forms of graphical displays, but it was not until the 16-color, 640x200-pixel CGA (Color Graphics Adapter) monitors began shipping with IBM PCs that most people had access to "real" graphics. To compensate, some pretty clever souls came up with what has become known as "ASCII Art." ASCII (American Standard Code for Information Interchange), for those of you too young to remember when that was part of common computer parlance, is the basic set of numbers, letters, and special characters that all computers are capable of rendering based on unique codes assigned to them. For instance, ASCII character 48D (30H) is the number "0," 65D (41H) is upper case "A,"...

Log Polar Plane Stencil c1958 #332

Log Polar Plane Stencil c1958 - RF Cafe SmorgasbordCanadian website visitor Richard F. sent me this photo of his "Log Polar Plane" acetate stencil, circa 1958. As a collector of vintage of science / technical paraphernalia, he ran across this as part of one of his acquisitions. "Computing Aids" is printed on it. I had never heard of the log polar plane, but according to the Wikipedia entry, "In mathematics, log-polar coordinates (or logarithmic polar coordinates) is a coordinate system in two dimensions, where a point is identified by two numbers, one for the logarithm of the distance to a certain point, and one for an angle. Log-polar coordinates are closely connected to polar coordinates, which are usually used to describe domains in the plane with some sort of rotational symmetry. In areas like harmonic and complex analysis, the log-polar coordinates are more canonical than polar coordinates." The David Young, on the University of Edinburgh website, explains, "Log-polar sampling is a spatially-variant image representation..."

Engineering and Technology History Wiki (ETHW) - Dr. Dave Leeson #331

Engineering and Technology History Wiki (ETHW), Dr. Dave Leeson - RF Cafe SmorgasbordIf you have not yet discovered the Engineering and Technology History Wiki (ETHW) website, now would be a good time to surf on over and take a look at the vast resources there - particularly the "Oral-History" series of in-person interviews of our field's top scientists and engineers. Among them are Dr. Harold Beverage, Dr. Ulrich L. Rohde (N1UL), Harold S. Black, Harold A. Wheeler, Dr. Irwin Jacobs and Dr. Andrew Viterbi, and of particular significance to me, Dr. David B. Leeson (W6NL), founder of California Microwave and Ham radio contesting champion. Many of the oral interviews were conducted in the pre-Internet era and some of the people are no longer with us. A few days ago, I had the honor of being contacted Dr. Leeson as part of his search for information he wants for some work he is doing. His name is familiar to amateur radio contesters who participate in DX (long distance) events...

What Does My Overheated Transmissions Have to Do with Admiral Grace Hopper? #330

What Does My Overheated Transmissions Have to Do with Admiral Grace Hopper?r, Kirt's Cogitations #330 - RF CafeLast week Melanie and I drove down to Greensboro, North Carolina, to attend our daughter's wedding. The weather was typically hot there, but not out of the norm. All went well at the small ceremony. Both bride and groom showed up, as did the minister and necessary witnesses. After the blessed event was over, we headed back northward to our humble abode in Erie, Pennsylvania. Our route upon exiting NC is I81 for a few miles in Virginia, then north onto I77, up to Rt. 19, then I79 all the way home up and down mountains for a few hundred miles. Our 2011 Jeep Patriot has never had any mechanical issues, but then it only has 81k miles on it and is kept in the garage. That day, though, the transmission overheating idiot light illuminated while on I81 - not a particularly hilly stretch. The outside temperature there was about 80 °F. I had noticed a slightly higher pitch sound from it while going uphill, but didn't think anything of it until the light came on. (On−Trak Automotive Services)...

COVID-19 Vaccination Effort Has No Statistically Significant Control Group #329

COVID-19 Vaccination Effort Has No Statistically Significant Control Group, Kirt's Cogitations #329 - RF CafeLet me begin by stating that in general, I am not an "anti-vaxxer." Since my days in the USAF, I have chosen to get an annual flu shot, my kids received all the required / recommended vaccinations during their school years. I've even had the second-generation shingles shots. No problemo. All those vaccines were subject to the full scientific regimen of development and testing prior to being administered to the general public. The current crop of COVID−19 vaccines, however, are a major exception - especially the mRNA varieties. None have been thoroughly vetted with the traditional multi-year studies which include a very wide cross-section of voluntary participants. Furthermore, none have been approved by normal guidelines - these are emergency approvals. Statistical studies were performed which attempted to correlate cause and effect. If necessary, necessary modifications to the formulation were made and then trials began anew. Once the medical and science community had enough data...

PS Magazine: The Preventative Maintenance Monthly #328

PS Magazine: The Preventative Maintenance Monthly, Kirt's Cogitations #328 - RF CafeA few times in the past I have mentioned the U.S. Army's long-running comic-book-style of training material for vehicle maintenance. It began in 1940 under the title of The Army Motors and ran through the end of World War II. In June 1951, at the beginning of the Korean War, the publication was re-introduced as PS Magazine - The Preventative Maintenance Monthly, where the "PS" part stands for "Post Script," a la the "p.s." you might put at the end of a written letter. In this case the "p.s." is a post script to the regular Army vehicle maintenance manuals. I recently happened to run across the RadioNerds.com's extensive section on PS Magazine, and it is a treasure trove of downloadable PDF versions of the magazines. As you can see from the cover illustrations and the contents, its appeal was primarily to the predominantly male vehicle maintenance force...

How Long Is 1 Trillion Seconds? #327

How Long Is 1 Trillion Secsonds? Kirt's Cogitations #327 - RF CafeEngineers are entirely comfortable with numbers multiplied by very large powers of 10; that is, with many trailing (or leading if a decimal) zeros after the significant figures. A terahertz is 1 x 1012, or 1 followed by twelve zeros, or 1,000,000,000,000. A picosecond is 1 x 10-12, or eleven zeros between the decimal point and the one, or 0.000000000001. The mass of the sun is approximately 1.9885×1030 kg, or 1,988,500,000,000,000,000,000,000,000,000 kg. The mass of an electron is approximately 9.10938×10−31 kg, or 0.000000000000000000000000000000910938 kg. We don't even break a sweat when punching those kinds of numbers into a calculator. We're used to it. When most laypeople these days hear politicians nonchalantly toss around figures in the trillions of dollars regarding a country's deficit or planned new spending packages, or the net worth of Amazon's Jeff Bezos, Tesla's Elon Musk, and Donald Trump, they have no concept of how big the numbers are...

1940 Sears Amateur Radio & Test Equipment Catalog #326

1940 Amateur Radio & Test Equipment Catalog Sears Catalog Kirt's Cogitations #326 - RF CafeRF Cave visitor and contributor Joseph Birsa (N3TTE), sent me a note about yet another edition of a special purpose catalog published by Sears - the Sears 1940 Amateur Radio, Test Equipment, Sound System Catalog. A little research revealed that it was actually an extended version of the 1940 Sears, Roebuck and Co. Superior Amateur Equipment and Radio Service Supplies - 64 versus 48 pages, respectively. Even the standard edition Sears, Roebuck Fall 1941 Catalog contained a large section dedicated to radios and equipment. The cover on the shorter catalog makes me think of The Radio Boys series of books, where a cadre of four early 20th century teenagers experienced adventures centered around build and operating wireless equipment. Hallicrafters, National Company, Meissner, and Hammarlund receivers and transmitters were offered for sale. Bliley and Silvertone...

Inventors and Their Inventions - #325

Inventors and Their Inventions, Kirt's Cogitations #325 - RF CafeWhen doing some research for creating a new quiz on inventors and their inventions, I decided to look for people according to their countries. I almost always do image searches since doing so does a good job of filtering out pages that merely mention the topic of interest. My first Google search was "american inventors." I expected to see the familiar faces of Thomas Edison, Henry Ford, George Westinghouse, Marie Curie, Alexander Graham Bell, George Washington Carver, Edwin Armstrong, Hedy Lamarr, Benjamin Franklin, Robert Goddard, Albert Einstein, the Wright Brothers, Samuel Morse, William Shockley, etc. Those are the names that first come to my mind, and admittedly the list is dominated by White men. Imagine my surprise when the Google search results belied my perception. Take a look at the first few pages of results to see what I mean. Next, I moved on to an image search for "canadian inventors..."

QST Christmas Covers - #324

QST Christmas Covers, Kirt's Cogitations #324 - RF CafeAs our traditions are besieged by malcontents determined to denigrate, impugn, and ultimately erase memories of holidays and events that have meant so much to families and friends, I feel compelled to resist the movement by documenting parts of the past that will cause us to wax nostalgic over our cherished traditions. Intimidation and violence is part of the strategic calculus; we have seen it in spades in 2020, and 2021 promises to be even worse. The Cancel Culture might eventually win out with the complicity of government agents both elected and unelected, but I'm not going down without a fight. Here is a collection of twentieth century, December issue QST magazine covers with Christmas themes that will no doubt be familiar to many of you. Finding them was more difficult...

December 24, 2020

Engineering Documentation Methods Questionnaire

Engineering Documentation Methods Questionnaire, North Dakota State University - RF CafeRF Cafe visitor Michael Maassel, an electrical engineering professor in North Dakota State University's Electrical and Computer Engineering Department, requested that I post these few questions to help him effectively prepare students taking senior-level (aka "Capstone") design courses for a real-world experience after graduation. Says the good professor, "The biggest headache I have is getting the students to document their work, both in hardware and in software. Currently, I am requiring that the students use a quad line notebook. This has not been very successful." How do you handle documentation in your every-day work?

Radio Boys Book Series

Radio Boys Book Series, Kirt's Cogitations #323 - RF CafeFor many years Melanie and I have been collecting and reading The Radio Boys series of thirteen books, which were written in the 1920s by Allen Chapman. It was a time in history when the miracle of radio communications was capturing - even enrapturing - the public with its seemingly miraculous ability to convey messages across town and around the world without the need for wires, hence "wireless." The stories center around four teenage buddies, namely Bob Layton, Joe Atwood, Herb Fennington, and Jimmy Plummer (aka Doughnuts") who, with the assistance of a local pastor, Dr. Dale, took an avid interest in radio and built from scratch a successful crystal radio. Their enthusiasm compounds upon itself as adventures and experiences using wireless foster interest in building better receivers and then building transmitters for sending Morse code and audio ("phone"). In order to appeal to his intended audience - primarily young boys - villains, good guys, hapless bystanders, government agents, local law enforcement, family, and even the occasional damsel in distress...

The New Normal - Face Masks Forever

The New Normal - Face Masks Forever, Kirt's Cogitations #322 - RF CafeAbout a decade ago, photos began appearing on news websites showing Chinese citizens walking around wearing face masks in order to filter out the massive air pollution pouring from city factories and coal-fired electric power generation plants. Articles were written advising on the best types of face masks to use while visiting or working in China. The only topic about China competing for shock factor at the time was the rash of suicides at Foxconn as the poor soulless, hopeless workers who build our inexpensive electronics products jumped from upper factory windows and roofs. Since around March of this year, nearly every location in the United States and around the world is looking like China did for the entire last decade. A worldwide pandemic was declared because of a deadly virus which originated from the Wuhan area of China...

Power Equivalent in the Electricity-Water Analogy

Power Equivalent in the Electricity-Water Analogy, Kirt's Cogitations #321 - RF CafeHave I mentioned that my YL, Melanie, decided she would earn her Amateur radio Technician license? After living in a household with a bilingual husband (English and Electronics) for nearly 38 years and having become fairly proficient at ETL (electronics as a third language*), Melanie decided to earn her Technician license. She has never delved into the technical aspects of electricity / electronics, but has, along with hearing me speak of it (too) often and having proof-read my writings and scanned and OCR'ed more than a thousand articles from vintage electronics magazines, her gray cells are permeated with the vocabulary, lingo, jargon, vernacular, slang, and argot of the realm. Being an expert test taker, she will undoubtedly pass the written test with flying colors. With much self-restraint, I have avoided offering my sage advice and knowledge during her studies of the ARRL's Ham Radio License Manual. The current edition is the 4th, being valid from 2018 through 2022. Melanie has asked for a little clarification on SWR, decibels and couple other minor topics, but otherwise has progressed...

The 3D Smith Chart: From Theory to Experimental Reality

The 3D Smith Chart: From Theory to Experimental Reality - R FCafeThe world was introduced publically in 2007 to the concept of a 3-dimensional Smith chart by Chris Zelley. In article published in IEEE Microwave Magazine entitled, "A Spherical Representation of the Smith Chart," the radically new concept was illustrated on the surface of a ping pong ball using a felt-tipped pen (thumbnail at left). Inspired by the sight, Andrei A. Muller and a small team of developers in 2013 created a version of the 3D Smith Chart in software using the Java language that allows it to execute on any platform. In 2017, an expanded functionality commercial version of 3D Smith Chart was released at a very modest price. A number of articles have been published on the topic extolling the unique ability of a 3-dimensional complex impedance volume to expose...


Morse Code in "Western Union" Song

Morse Code in the "Western Union" Song, Kirt's Cogitations #318 - RF CafeThe other day a song entitled "Western Union" played on my local over-the-air oldies radio station. It was released by the group The Five Americans in 1967. I've heard it many times before, but it finally occurred to me that the use of Morse code-like symbols in the refrain made it a perfect candidate for a spot here on RF Cafe. The full lyrics of "Western Union" can be found at the bottom of the page, but notice the "Dah-Dit-Dah-Dit-Dah" repeats in the refrain. Even though I'm a licensed (as of 2010) Ham, my shameful (according to some veterans) status as a post-Morse-code era did not require demonstration of code proficiency. As such, my lack of a Morse code deciphering ability required that I rely on an online translator for considering what the code might be. Depending on how you separate the dits and dahs, the string of characters can be interpreted as TETET (- . - . -), TAA (- .- .-), KA (-.- .-), NK (-. -.-), CT (-.-. -) or other combinations, none of which seem to mean anything in particular...


Buy & Sell Ham Radio Operator Homes

Amateur Ham Radio Operator Homes - Buy & Sell, Kirt's Cogitations #318 - RF CafeA couple years ago a house two streets away had an estate sale after the elderly gentleman who owned it passed on. There was a lot of old amateur radio gear for sale, and most of it had been bought early in the morning, right after the beginning of the sale according to the man's daughter who was on-hand. The newspaper notice mentioned the Ham equipment. In the back yard was a nice 40-foot crank-up tower that was a bit weather-worn, but otherwise appeared to be in good condition. She said that was the first item sold. I didn't ask how much she got for it. The house was to be sold, and they were glad to have the tower gone before listing it on the market. I have wondered in the past when seeing a "For Sale" sign in the lawn of a house with one or more radio towers in the yard how much they would impact the sale price. Some Hams would plan to take...


The Lincoln Vocational Technical Center - A Partial Autobiography - #317

The Lincoln Technical Center, Annapolis, Maryland, Kirt's Cogitations #317 - RF CafeLincoln Vocational Technical Center. One day in late spring of 1973 I found myself walking around the gymnasium of Annapolis Junior High School (AJHS) trying to decide which courses I would prefer upon beginning tenth grade the following fall. It was one of the final days of ninth grade, which had been by far my least happy year in school. Living in Mayo, Maryland, I and my fellow neighborhood ninth graders should have attended Southern Senior High School (SSHS) in Harwood, Maryland, where our predecessors had gone for ninth grade, but overcrowding caused the Anne Arundel School Board wizards to decide that for at least that year, we would remain at AJHS for another term. Historically, kids from my area went to AJHS only for seventh and eighth grades and then switched to SSHS. Annapolis, being the capital city of Maryland, was significantly more urban than the rural areas which SSHS type people were accustomed to. The clientele was much more aggressive in the big city. Sure, we had our "red neck greaser" rowdies in the southern part of the county, but at least their parents would whip them if they got caught getting into trouble. The north county parents, we believed at the time...


How to Remove Clutter from Online Document Displays - #316

How to Remove Clutter from Online Document Displays, Kirt's Cogitations #316 - RF CafeIf you are annoyed by pop-ups and extraneous framework elements and/or SEO (search engine optimization) tracking code accompanying application notes, white papers, and images, and videos, many times you can get rid of them by editing the URL displayed in your browser address bar. Compare the displays in this set of screen captures based on the original URL provided in an e-mail (top) to the one where all the extraneous terms have been removed from the URL (bottom). Note that the yellow highlighted components have been eliminated. Often, I remove that stuff from hyperlink URLs before sending my visitors to websites. Companies don't particularly like me doing that, but doing so helps maintain your privacy. URLs in e-mails are particularly likely to contain appended code that contains one or more "&utm_" parts. UTM is the Urchin Tracking Module introduced by Google Analytics' predecessor Urchin and are now supported by Google Analytics. They typically ....



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Kirt Blattenberger - RF Cafe Webmaster

Copyright: 1996 - 2024


    Kirt Blattenberger,


RF Cafe began life in 1996 as "RF Tools" in an AOL screen name web space totaling 2 MB. Its primary purpose was to provide me with ready access to commonly needed formulas and reference material while performing my work as an RF system and circuit design engineer. The World Wide Web (Internet) was largely an unknown entity at the time and bandwidth was a scarce commodity. Dial-up modems blazed along at 14.4 kbps while tying up your telephone line, and a nice lady's voice announced "You've Got Mail" when a new message arrived...

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