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 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...
1/21/2020  If 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 ....
12/20/2019  The year was 1941 and the radio industry was going strong worldwide. Sales of receivers was hitting new highs every quarter and service shops had all the work they could handle for repair, upgrades, and installations. The radio broadcast realm was scrambling to build new studios, install transmitters and antennas, hire announcers and managers, and upgrade to keep up with the quickly evolving business. Take a look at these 24 full pages of radio-related products offered by the Sears, Roebuck Company in their Fall and Winter 1941-1942 catalog. It is typical of most radio manufacturers' catalogs of the era. For the last decade engineers had been working overtime to satisfy consumer demand for fancier cabinet designs with fancier features. So strong was public demand that people put their highest priority on acquiring the latest models (not unlike the smartphone craze of today). Then, ...
11/21/2019  Every once in a while an RF Cafe visitor writes to let me know that he or she found one of the vintage electronics magazine articles I post regularly useful. It helps to validate my efforts, which is critical for motivation to continue. A couple days ago Mr. Dave Jones (N1UAV), sent me a note about the stacked television antenna project he undertook after finding the "How to Stack TV Antennas to Increase Signal Strength and to Reduce Ghosts" article from the November 1965 issue of Popular Electronics magazine. His location about 90 miles outside of Nashville, TN, is a challenge for trying to receive a good signal from a television station from both an attenuation and multipath signal degradation perspective. Dave began with a single antenna, but was not happy with the performance. The results of adding the second antenna is amazing ...
8/2/2019  Sometime around 1980, while stationed at Robins AFB, Georgia, I finally succumbed to the peer pressure of other more sophisticated audiophiles in the barracks and bought a "real" stereo. Unlike my roommate who had a full compliment of rack-mounted gear, my meager enlisted military pay only allowed for a mid-grade instrument. The solution was a Sansui TA−300 Integrated Tuner Amplifier. It put out a whopping 30 watts per channel, but unlike my existing radio (a Readers Digest 800−XR), those 30 watts were nearly distortion free when driving good speakers. Having only the pathetic 5 W speakers that came with the 800-XR, I designed a set of speakers rated for 60 W, and built the enclosures myself in the base woodshop. Unfortunately, in preparation for a household move about 20 years ago, I sold the Sansui and the speakers ...
5/20/2019  As you already know if you are planning to be at the International Microwave Symposium (IMS) this year, it is being held from June 2nd through the 7th in Boston, Massachusetts. The last time the IMS show was in Boston venue was 2009, and RF Cafe was there. It was my very first IMS show. The entire day was spent taking photographs and meeting as many RF Cafe website advertisers as possible. I also got to visit with a few people from companies I used to work for. The National Electronics Museum had a very nice display set up showcasing the evolution of the Microwave industry. Up until a couple weeks ago, Melanie and were planning on returning this year to the IMS show, but some family matters have required some extensive travel lately ...
5/10/2019  Knowing that I am an avid consumer of literature pertaining to time and astronomy, Melanie picked up a book at the library for me titled, Longitude: The True Story of a Lone Genius Who Solved the Greatest Scientific Problem of His Time, by Dava Sobel. When Christopher Columbus discovered America, his intended target was, if you recall, the Indies. His original charter was to find a direct westerly pathway from the Atlantic coast of Europe to the immensely profitable trade production region of the Indies as an alternative to to sailing around the treacherous Cape of Good Hope at the southern tip of Africa. How could such an experienced navigator have missed his mark by so far, you might reasonably ask? Didn't Columbus know how to use a sextant, or at least have a navigator who could? The answer to the second question is, "no." The answer to the first question is complicated ...
3/7/2019  Just about everyone who has worked in the radar field for a long time is familiar with the name of Dr. Robert M. Page. He was the first to come up with the concept of monopulse radar, and he invented the familiar Plan Position Indicator (PPI) radar display and the RF duplexer which allows one antenna to be connected to both the transmitter and the receiver. Amazingly, I recently received an e-mail from Dr. Page's son, John Page. An interest in his father's career combined with insight that only growing up under the loving care of Dr. Page can provide has afforded him some unique tidbits of information that many (most, per John) historical accountings omit. Rather than me summarizing his letter, you will want to read it yourself as presented below. World War II aficionados will particularly appreciate the information. John pays homage to his father's co-workers ...
2/18/2019  If you were around here in 2014, you might recall my publishing a paper titled, "Drone-Based Field Measurement System™ (dB-FMS)™." Since then, I have seen a few companies doing this (here, here, here, here, and many more); others are coming online all the time. Those people have actually implemented working systems that seem to perform very well. I'm not saying they got the idea from my article because more than one person can have a brilliant idea ;-). It's just good to know that my idea had some merit in the real world ...
February 11, 2019  Hello. My name is Kirt, and I'm a vintage wired and wireless communications publication addict. This affliction has had a hold on me for going on two decades now. Call it my middle age crisis. At sixty years old, there is no sign of abatement in enthusiasm. Nearly every day I still find myself reading and commenting on articles and advertisements from mid-last-century magazines, newspapers, and catalogs. Maybe I'm hopeless and will never be able to kick the habit. I'm not alone, though, based on some of the feedback received from RF Cafe visitors. for that reason and others, maybe, in truth, I've grown comfortable with my addiction. While perusing a few vintage newspaper editions from the World War II era looking for relevant stories, I ran across this November 1, 1940 (exactly 78 years ago) special section in the Harrisburg Telegraph titled, "Radio Industry Marks 20th Anniversary." It contains many stories ...
November 1, 2018  It is probably safe to say that most people, especially today, believe that the United States was suddenly and unexpectedly thrust into involvement in World War II on December 7, 1941, when the Japanese navy launched a surprise attack on Pearl Harbor. The fact is the U.S. was "unofficially" engaged for over a year beforehand by "lending" both equipment and personnel to British, Russian, Chinese, French, and other militaries as part of their effort to drive back invading German, Italian, and Japanese Axis forces. World War II actually began in the Fall of1939 with Hitler's invasion of Poland. Americans, being safely separated from the front lines by the Seven Seas, knew little of and were concerned little about the goings on "Over There." Once the call to arms was sounded with the Pearl Harbor attack, the country quickly and enthusiastically converted to full wartime mode. Manufacturing plants ...
10/25/2018  In all my years of repairing and restoring old radios, I have never had the occasion to re-string a dial cord. There are many variations on dial cord construction and diameter, but there are even more variations in that way the path around the tuning shaft, tuning elements, and indicator dials are implemented. Larger radios with lots of room in them are relatively easy to re-string and usually take a fairly straightforward path, but smaller portable multiband radios like my 1970's-vintage Realistic Patrolman−50 are a bit of a challenge, as I found out recently. A Web search on recommendations for how to replace dial cords results mostly in frustrated handymen who have seemingly given up on the job. It is easy to understand why, especially on a ridiculously complicated routing scheme. My only guess as to the need for the multiple pulleys and specific number of wraps around each is because of the need to maintain very solid contact while tuning four separate variable capacitors ...
9/10/2018  Late in 2016, news outlets began reporting on American and Canadian diplomats stationed at their respective embassies in Cuba complaining of dizziness, nausea, headaches, ringing in the ears, and other seemingly sound-related illnesses. Similar reports have come out of China as well. At the time, doctors and scientists investigating the phenomenon thought maybe some sort of weaponized sonic beam was being directed at the personnel. Certain people were affected while others nearby experienced no such phenomena, leading researchers to believe that the presumably sonic beams were highly concentrated and directional. Some of the targeted personal were diagnosed as having suffered mild traumatic brain injury with likely damage to the central nervous system ...
9/4/2018  In 2010, I posted a short piece about where to look on the Web to learn what upper management, board members, and large investors were doing with insider company stock trades. At the time, the MSN Money website had a tool where you could enter a company's stock symbol and get a readout of who was buying and - more often that not - selling stock. That web page is gone, but I found the same information on InsiderCow.com. The dollar amounts are truly staggering to people like you (likely) and me (definitely). Numbers reported are sale values, not profit to the stock holder. Many of the stocks were issued as either grants or options, but even outright purchased stocks are included as well. Regardless, prepare to have your jaw drop if you have never seen this type of data before. Some of the more familiar technology companies have been selected for examples ...
7/10/2018  While not quite the equivalent of an Elvis sighting, I was utterly surprised to see an open Radio Shack store in the Ashtabula Towne Square Mall during a recent trip to Ohio. As you can see in the photo, it is a shell of a store, with products on display only along the walls. Do you remember the days when every shopping mall and plaza had a Radio Shack crammed full of stereos, radios, calculators, antennas, computer accessories (and the TRS-80), toys, and of course a huge portion of the store dedicated to electronic project components? I had a "Battery Club" card for a couple decades, and a current catalog was always on my bookshelf. If, as the old saying goes, "Misery loves company," then the good folks at the Ashtabula Radio Shack can at least take some solace ...
6/25/2018  The Old Farmer's Almanac (OFA) has been on my annual need-to-buy list for as long as I can remember. It is chock full of useful data for sunrise and sunset times*, high and low tide times, crop planting days, first and last frost days, and significant astronomical events. There are stories of interest on topics ranging from canning your garden's harvest to how to view a solar eclipse. - often from noted authors, but also from lay people. I also enjoy the monthly "on this day" type tidbits and the homey short story relating to the time of year. After 225 years of continuous publication, it still features the hole in the upper left corner to facilitate handily hanging it on the wall of your shed -- or outhouse. I gave a 1961 edition of the Old Farmer's Almanac found on eBay to Melanie as a birthday present this year ...
5/15/2018  This rare HP 5212A Electronic Counter was found in a second-hand shop sitting in with a bunch of random electronic gear. The "HP" on the front panel piqued my attention, so I carried it to the counter and asked the nice lady to plug it in, figuring if the front panel lit up and none of the smoke that makes electronics work leaked out, I'd buy it. It did, it didn't, and I did, respectively. The outside condition is pretty good, with most of the scratches being on the top and bottom. Some oxidation is present on the bare aluminum chassis components, but a little ...
4/30/2018  If you grew up in the era of rooftop television antennas, then there is a good chance you are familiar with the electromechanical antenna pointing systems that were often installed as well. Alliance, Channel Master, Cornell Dubilier, Radio Shack, RCA, Winegard, and others made low cost, light-duty rotators for television antennas. Ham radio antenna rotators were/are more robust in order to handle higher weight and wind loads. Many television antennas also cover the FM radio band (88-108 MHz), allowing them to do double duty. Being an unapologetic technology renaissance man, I recently purchased (on eBay) a vintage Alliance Model U−100 Tenna−Rotor that was unused in the original ...
4/10/2018  The manned space program has unarguably provided mankind with many new and innovative tools, medicines, electronics, materials, physics, materials, appliances, and mathematics. Know officially as "spinoffs," products like the portable heart defibrillator unit, the portable vacuum cleaner, freeze-drying food processors, powdered lubricants, memory foam, quartz clocks and battery-powered tools. Many NASA inventions have not found an application in your basement or garage, however, because their purpose is too specialized. Take, for instance, the ZeRT, or Zero Reaction Tool ...
4/3/2018  You might have noticed that since last November the engineering and science themed daily RF Cafe header images have been much larger than those which graced the pages in the past. The change was motivated mainly by a desire to make them more viewable on the tiny screens of mobile phones. It also gave me the opportunity to include more information. In the process, I took the occasion of being on each daily engineering and technology history page to check on the validity of the long ago included hyperlinks to pages which validated dates of events. Use Wikipedia was avoided because of the joke-worthy reputation it had for bogus ...
3/25/2018  To be or not to be - that is the question: Whether 'tis nobler in the mind to suffer the slings and arrows of outrageous bi-annual clock shifts, or to take up arms against a sea of contradicting justifications for and against its existence for DST, and by opposing, end it. Twice each year, a majority of the western world is subject to a manmade disruption in circadian and habitual cycles with an inane one-hour clock change on and off of "Daylight Saving(s) Time" (DST). Some historians claim that Benjamin Franklin joked about DST in the 18th century, but it was New Zealander George Hudson who proposed the modern day clock ...
3/12/2018  Have you ever started a relatively simple investigation into a trivial matter, only to find yourself going down the metaphorical "rabbit hole" even after finding the original answer? Such was the case for me when someone sent me an e-mail with a signature that included his amateur radio call sign. The first three characters, KB3, matched mine and that got me wondering on what date his call sign was granted compared to mine. Let us say for example* the writer's call sign was KB3PGM and mine is (actually) KB3UON. I looked them up in the FCC's ULS self-serve license ...
2/14/2018  If, as the saying goes, "Misery loves company," then you will appreciate the following. Whilst perusing the December 2017 issue of NASA's Motion Design supplement to their Tech Briefs publication, I ran across the image to the right in an article titled, "Trends in Hydraulic Filtration" (areas of interest are quite diverse here at RF Cafe). After reading the caption stating that the holes were "fire holes," the first thing that came to mind was ESD damage. Sure enough, upon going back and reading more of the story (provided by Argo-Hytos), I found ...
12/5/2017  Another era, sadly, has come to an end. H. Ward Silver (aka Ward Silver, NØAX) has announced the end of his monthly column, "Hands-On Radio," in QST magazine. The title of each column was enumerated as "Experiment #nnn," followed by the subject. To wit, "Experiment #179 Maxwell's Equations - The Wave Emerges" is Mr. Silver's final column, appearing in the December 2017 QST. "Hands-On Radio" topics ranged in intensity from relatively simple discussion on calculating power dissipation in resistors, capacitors, and inductors to more heady treatises on subjects like electromagnetic fields within coaxial cable and waveguide to Maxwell's equations. Mathematics, too ...
11/27/2017  One of my favorite old-time radio personalities, Paul Harvey, had a trademarked feature titled The Rest of the Story. For those of you not familiar with the format, Mr. Harvey would begin his story talking about particular life aspects of a person that, while remarkable, usually had no connection with the person's eventual claim to fame. The listener's challenge was to guess who the person was before it was revealed at the very end, followed by, "... now you know --- the rest [emphasis] of the story." As far as I know the story of FM radio inventor Edwin H. Armstrong was never a subject, although it certainly met the criterion. I've already let the figurative cat out of the bag, so you already know my subject ...
 From May 9th through the 11th in the year of our Lord 1958, the very first "Jamboree on the Air" (JOTA) was held by the Boy Scouts of America (BSA). The American Radio Relay League (ARRL), in conjunction with the BSA, is promoting this year's 60th anniversary event occurring from October 20-22. As you might imagine, quite a lot has changed over 59 years in terms of equipment, but the basics in terms of encouraging and assisting the next generation of licensed Hams remains as always the primary goal of organizers. The Boy Scouts, of course, join in for the fun and learning experience. Jamboree on the Air events, held in October, do not coincide with the National Scout Jamboree, held in July ...
10/9/2017  Nikola Tesla was born in 1856 in Smiljan, Austrian Empire, and died in 1943 in New York City. His life is so amply documented far and wide that regurgitating the information in books and blog posts would be a waste. Most of what you find there is second-hand, having gone through the filter of an author's preferences. I like to search for stories on various topics in their original publications; e.g., scanned newspaper and magazine archives. A hunt for early stories on Nikola Tesla turned up many 19th century examples from the Newspapers.com website. It is interesting that back in the day, men like Nikola and Edison were referred regularly to as "electricians." The oldest article I found on Nikola Tesla appeared in the July 1, 1889 edition of The Pittsburgh Dispatch, titled "The Electric Fiend" ...
8/29/2017  It's finally here - the Great North American Solar Eclipse of 2017! The amateur astronomy community has been anticipating and preparing for the event for a couple years. Astronomy magazine dedicated the entire August issue to providing detailed information on viewing suggestions along the entire path. Traffic from the Pacific Coast of Oregon to the Atlantic Coast of South Carolina will probably be a challenge as people vie for positions as close to the centerline as possible. Those who manage optimal locations will see about 2 minutes and 40 seconds of total darkness. Others within the 68-mile-wide path of totality will see from a fraction of a second up to the full extent. According to a calculator on the Vox website, we will only see a 76.2% eclipse, which will barely darken our skies ...
8/21/2017  Hmmm.... let us see what made the front page of the July 1, 1948 edition of Murray Hill, New Jersey's, The Madison Eagle newspaper: "Man Found Dead, Wedged in Drain on Park Edge," "Lawyer Fined $50 on Zone Charge," and Sandra Dean Stevenson had been born two weeks earlier. Oh, also included was "Invention Replaces Vacuum Tube" and "Local Man Invents New Device in Electronics for Bell Lab; Could Revolutionize Radio." Page 10 ran, "Bell Laboratory Releases Data on Newly Invented Transistor." It is widely known that Drs. Brattain, Shockley, and Bardeen formerly announced on December 23, 1947, within the walls of Bell Labs ...
8/18/2017  We have all been treated to a seemingly endless series of headlines portending rising ocean levels and the ensuing drowning of costal cities due to melting ice in the polar regions. This phenomenon ostensibly is brought on by the exponential increase in carbon emissions from developing third-world countries as well as established first-world countries in the post World War II era ... or was it post Vietnam, or maybe post Gulf War? The reference keeps changing, but it definitely began occurring since at least 1990, right? There is a problem, though. In the early and mid 1970s climate scientists began warning us of an approaching ...
8/9/2017  For some inexplicable reason, it seems that of the many articles I read dealing with antenna and feedline efficiencies, rarely is the receive side of the equation addressed. Yes, transmit power is expensive and there is a legitimate reason to reduce losses when converting power amplifier output to in-the-air power, especially for DX operations. However, it doesn't do much good to launch the full permissible 1,500 watts PEP and make a contact on the other side of the world if your system cannot receive a reply because of the excessive line loss and/or mismatch loss between your antenna and your receiver. Antennas and feedlines are reciprocal elements so if ...
7/26/2017  Friends, former employees, and fellow lovers of all things electronic, we are gathered here today to remember and honor our lifelong friend and enabler of our hobby and passion, Radio Shack - once a Tandy company, as we are familiar with it. Radio Shack has lingered in failing health for a decade, all the time keeping a brave face on its dwindling number of stores. Caretakers attempted a variety of infusions and transplants in an attempt to save the American stalwart electronics retailer. Alas, a confluence of poor management ...
6/14/2017  For Mother's Day this year, the kids and I got Melanie a 23andMe DNA testing kit. She has spent a fair amount of time over the years researching the family lineage which, in case you care, traces back primarily to Germany and Switzerland. Along with some of the online ancestry websites, she searched the U.S. Census database for immigration and early American household information (number of people, ages, names, occupations, etc.) The entire 1930 Census form consisted of a single page seeking basic information on whether you own or rent, value of the home, live on a farm or not, color or race, ...
6/9/2017  Long-time RF Cafe visitor and occasional contributor Gary Steinhour, KF6U, recently sent me a note saying he had acquired a very used Heathkit DX-60B amateur radio transmitter and was in the process of restoring it. Gary's first transmitter as a freshly minted Ham over 50 years ago was a DX-60, so this was an effort to satisfy a nostalgic emotional attachment. The project is complete now, and boy does it look nice! Gary provides a brief account here ...
6/7/2017  If you have ever seen the result of a lightning strike on electronic equipment, then you know how devastating it can be - often total destruction that includes molten metal. Woe be unto any human operator who happens to be in contact with it at the time of the strike. Unprotected antennas are begging for contact. Shortly after leaving a company where I worked on a Tx/Rx system for a phased array weather radar I got word that the indoor equipment rack took a major hit because the guy who maintained the site forgot to reconnect a lightning rod system cable after moving it during ...
6/1/2017 Miscellaneous Earlier Smorgasbords and Factoids: |
