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Today in Science History

Temperature Calibration for Protecting Food Safety

Axiom Test Equipment Blog: The Role of Temperature Calibration in Protecting Food Safety - RF CafeTranscat | Axiom Test Equipment, an electronic test equipment rental and sales company has published a new blog post entitled "The Role of Temperature Calibration in Protecting Food Safety" that covers how temperature calibration tools such as dry blocks and calibration baths are precise, accurate tools for measuring temperatures during food production cycles. Complying with food temperature safety regulations helps deliver safe foods with long shelf lives, while noncompliance can result in health issues with serious legal consequences. Dry blocks and temperature calibration baths are both capable of measuring wide temperature ranges with high resolution and accuracy although they work in much diverse ways. A temperature dry block heats or cools a metal block to a precise temperature...

Fix Those Printed-Board Defects

Fix Those Printed-Board Defects, December 1959 Electronics World - RF CafeMy long-established collection of soldering aid and tuning wand tools still gets a fairly regular workout - but not necessarily for soldering tasks. Most are non-metallic, meant for bending and poking, and are very strong and heat resistant. The metal types are still required for direct contact with molten solder. One of the best tips offered in this 1959 Electronics World magazine article is for when replacing a leaded component on a PCB. If possible, rather than heating the landing pad and plated through-via to remove the leads, just clip the leads far enough from the PCB surface to create a post or loop to solder the new component to. Doing so creates a mechanically sound solder joint without undue risk of damage to the PCB metal or laminations. Interestingly, the PCB in this article contains a vacuum tube plug-in socket...

Bell Telephone Labs: Coherent Light

Bell Telephone Laboratories: Coherent Light, August 1962 Radio-Electronics - RF Cafe"Multichannel light highways for communications are still far from realization. But with continuous sources of coherent light available, it becomes possible to explore the problems of modulating, transmitting, detecting, amplifying and, in general, controlling light for possible communications applications." That claim was made in a 1962 Bell Telephone Laboratories (Bell Labs) info ad in Radio-Electronics magazine. More than six decades later, the job is being handled by microcircuits with integrated laser transmitters and receivers. High quality optical fiber provides information transport across the neighborhood, city, state, country and world. A big list of other Bell Labs innovations is at the page bottom. Created a century ago in 1925, Bell Telephone Laboratories' name has been Nokia Bell Labs...

Wilhelm Röntgen: A Short Biography

Wilhelm Röntgen: A Short Biography - RF Cafe Wilhelm Conrad Röntgen, a luminary in the field of physics, was born on March 27, 1845, in Lennep, a small town in the Rhine Province of Prussia, now part of Germany. His father, Friedrich Conrad Röntgen, was a cloth manufacturer, while his mother, Charlotte Constanze Frowein, hailed from an affluent and distinguished family of Dutch descent. Wilhelm spent his early childhood in Lennep before the family moved to Apeldoorn, the Netherlands, when he was three years old. His education began at the Institute of Martinus Herman van Doorn, a technical school in Utrecht. However, Wilhelm was expelled at the age of 18 after being falsely accused of sketching a caricature of one of his teachers, an injustice that deeply affected his academic trajectory. Röntgen's early academic path was unconventional...

Meet the Transistor

Meet the Transistor, January 1955 Popular Electronics - RF CafeShortly before Christmas, 1947, the experimental work of Bell Laboratories scientists John Bardeen, Walter Brattain, and William Shockley resulted in the world's first semiconductor transistor. With proper biasing, the germanium transistor demonstrated an ability to produce signal gain. The signal fed to the base resulted in a higher amplitude signal at the collector. Voila, the device which would ultimately replace the vacuum electron tube had been invented. The rest, as they say, is history. Aside from a few high power applications, the only new equipment produced that uses vacuum tubes are retro things like audio amplifiers and simple receivers. Of course, there is still a large cadre of vacuum tube users in the Amateur Radio real and vintage equipment restorers...

Generative AI Generates More E-Waste

Generative AI Generates More E-Waste - RF CafeIn Compliance magazine has an article entitled, "The Growing Use of Generative AI Will Generate More E-Waste." I queried ChatGPT about whether the claim is true. Summarizing its reply, ChatGPT admits is is a polluter. To wit: "Yes, the growing use of generative AI has the potential to contribute to an increase in electronic waste (e-waste). This stems from multiple factors related to the infrastructure and hardware required to support AI development and deployment. Here's how generative AI contributes to the problem and the broader implications: • Hardware Demand • Shorter Hardware Lifespan • Increased Energy Consumption • Consumer Devices • Recycling Challenges. To mitigate the e-waste impact of generative AI include designing hardware with a longer lifecycle, improving recycling technologies, adopting modular designs for easier upgrades, and using energy-efficient models that reduce the need for frequent hardware replacements. Additionally, promoting circular economy practices and enforcing e-waste regulations can help address the issue. Generative AI offers immense potential but addressing its environmental footprint, including e-waste, is essential for sustainable development."

Engineering & Tech Headlines <Archives>

• U.S. Pressures Japan for Selling Chip Kit to China

• Record September IC Exports for Korea

• FCC Issues Notices to Pirate Radio in NYC, Miami

• TSMC Posts Sharp Rise in Q3 Net Profit

• Nearly 40% of SMBs using AI

FM Receivers and Their Alignment

FM Receivers and Their Alignment, August September 1940 National Radio News - RF CafeFM radio noise immunity testing. 1940 was a big year in the commercial broadcast industry because it was when the FCC began licensing stations for FM operation. Amazingly, that was only four years after Edwin Armstrong first came up with his frequency modulation scheme - fast moving for the government. Simultaneously, equipment manufacturers were cranking out transmitters, receivers, antennas (new frequencies), writing installation and operation guidelines, training servicemen, and doing scores of other vitally important tasks. The advent of FM was considered a very significant technical improvement because of immunity to electrical noise interference. If for no other reason, you should look at this National Radio News magazine article...

What You Should Know About X-Ray Radiation in TV Sets

What You Should Know About X-Ray Radiation in TV Sets, November 1967 Radio-Electronics - RF CafeDuring the early era of color television, much editorial ink was spilled on the topic of x-radiation emitted from the high voltage power supplies within. This 1967 Radio-Electronics magazine article appeared toward the end of the problem. Those of us who were around for the excitement remember being told as children "Don't sit so close to the TV; it'll ruin your eyes." The ignorant among us thought the admonition was because focusing so close-up would be bad training for eye muscles. The real reason was danger of absorbing too much ionizing x-radiation from the high voltage vacuum tubes. Achieving bright, vibrant color with early tri-color cathode ray tubes (CRTs) required blasting the red, green, and blue phosphorescent dots on the back of the display...

Leaftronics Biodegradable Electronics

Leaftronics Biodegradable Electronics - RF Cafe"A research team headed by Prof. Karl Leo at TUD Dresden University of Technology have developed an innovative, nature-inspired solution that could revolutionize the electronics industry: Leaftronics." This innovative approach leverages the natural structure of leaves to create biodegradable electronic substrates with enhanced properties and offers a sustainable, efficient, and scalable solution to the global-waste problem. These findings have now been published in the journal Science Advances. Electronic devices, from toys to smartphones, consist of circuits. Specific substrates are used to manufacture these circuits..."

San Fran Circuits: ENEPIG PCB Surface Finish

San Francisco Circuits: ENEPIG (Electroless Nickel Electroless Palladium Immersion Gold) PCB Surface Finish - RF CafeSan Francisco Circuits, a premier provider of leading edge technology printed circuit boards, has published a new article on ENEPIG (Electroless Nickel Electroless Palladium Immersion Gold) PCB Surface Finish. ENEPIG is one of the most popular PCB surface finishes due to reduced palladium prices and its advantages over finishes like ENIG. Composed of four metal layers - copper, nickel, palladium, and gold - ENEPIG offers excellent protection against corrosion and the infamous "black pad" issue. ENEPIG: Ideal for Demanding Requirements ENEPIG supports various package types, including BGA, SMT, wire bonding, and press fit. With a thin gold layer (0.05μm - 0.1μm), it simplifies assembly and provides improved reliability...

The Ray of Mystery

The Ray of Mystery, 3/15/1896 The Warren Mail - RF CafeOn a whim, I did a search for the earliest appearance of Nikola Tesla's name in U.S. newspapers included in the NewspaperArchive.com database. This story from Mr. George Grantham Bain appeared in multiple newspapers within a few days of this March 5, 1896 edition of The Warren Times in Warren, PA, which coincidentally is not far from me here in Erie. The article reports on the role that Tesla's high voltage generators played in the development of x-ray images on fluorescent displays and on film (which Tesla termed "cathode photography"). It mentions how the term "cathode" is relatively new to the general public even though it had been around since 1832 when Michael Faraday introduced it in his work. Wilhelm Röntgen made the world's first x-ray image - of his wife's hand...

Michael Faraday: A Short Biography

Michael Faraday: A Short Biography - RF CafeMichael Faraday, one of the most revered experimental scientists in history, was born on September 22, 1791, in Newington Butts, a small village near London. His humble beginnings were in stark contrast to his towering achievements. Faraday's father, James, was a blacksmith of modest means, and his mother, Margaret Hastwell, managed the household despite financial difficulties. The family belonged to a small Christian sect known as the Sandemanians, whose values of humility, simplicity, and a focus on practical service profoundly influenced Faraday throughout his life. Faraday's early education was rudimentary, consisting mostly of reading, writing, and arithmetic. At the age of 14, he was apprenticed to a London bookbinder named George Riebau. This apprenticeship proved transformative, as it allowed young Faraday...

Open Neutral in a Single-Phase Electrical Service

Open Neutral in a Single-Phase, 120/240 Volt Electrical Service: Kirt's Cogitations™ #366 - RF CafeA neighbor approached me the other day regarding a strange occurrence with the electrical supply to his workshop, which is not attached to the house. The overhead lights were dim, and his small refrigerator was straining. Turning on or off various tools and lights caused changes in everything else. This guy is one smart cookie (and an excellent woodworker), and has handled all his own household electrical and plumbing issues for many decades, but he had never experienced such a situation. Fortunately, I have. Upon hearing his description, I immediately recognized it as a case of an open neutral in the circuit breaker panel. I have seen that before. Understanding what is happening can be made simple by realizing that once the neutral reference is gone, the two "legs" (phases) are in series with each other rather than in parallel...

Open Neutral in a Single-Phase Electrical Service

Open Neutral in a Single-Phase, 120/240 Volt Electrical Service: Kirt's Cogitations™ #366 - RF CafeA neighbor approached me the other day regarding a strange occurrence with the electrical supply to his workshop, which is not attached to the house. The overhead lights were dim, and his small refrigerator was straining. Turning on or off various tools and lights caused changes in everything else. This guy is one smart cookie (and an excellent woodworker), and has handled all his own household electrical and plumbing issues for many decades, but he had never experienced such a situation. Fortunately, I have. Upon hearing his description, I immediately recognized it as a case of an open neutral in the circuit breaker panel. I have seen that before. Understanding what is happening can be made simple by realizing that once the neutral reference is gone, the two "legs" (phases) are in series with each other rather than in parallel...

Electronics-Themed Comics

Electronics-Themed Comics, August 1962 Radio-Electronics - RF CafeThree more electronics-themed comics here, these from a 1962 issue of Radio-Electronics magazine. They represent a good spectrum of consumer electronics service issues of the era. The page 41 comic scenario is not likely to occur with a television today; it's more likely with a Li-Ion powered cellphone sitting in your pocket. The page 60 comic, on the other hand, is more likely to happen today with all the anti-theft devices used on in-dash devices like radios, GPS navigation units, and Ham (Amateur) and CB radios. Even without the anti-theft devices, good luck getting the dashboard apart enough to service the device. I recently replaced an in-dash air vent valve motor in my daughter's truck...

Material Perfectly Absorbs All Electromagnetic Waves

Material Perfectly Absorbs All Electromagnetic Waves - RF Cafe"A team of scientists from the Korea Institute of Materials Science (KIMS) has developed the world's first ultra-thin film composite material capable of absorbing over 99% of electromagnetic waves from various frequency bands, including 5G/6G, WiFi, and autonomous driving radar, using a single material. This novel electromagnetic wave absorption and shielding material is less than 0.5mm thick and is characterized by its low reflectance of less than 1% and high absorbance of over 99% across three different frequency bands..."

Making Circuit Components

Making Circuit Components, July 1969 Radio-Electronics - RF CafePart 1 of this "All About IC's" series titled, "What Makes Them Tick," author Bob Hibberd introduced the concept of semiconductor physics and doped PN junctions. It appeared in a 1969 issue of Radio-Electronics magazine. In Part 2, he discusses methods used to fabricate monolithic, integrated circuits (IC's) on silicon chips. Transistors, diodes, resistor, capacitors, and to some extent, inductors, can be built using a combination of variously doped junction regions, metallization, and oxidation (insulators). Technology has come a long way since 1969, including mask techniques, 3-D structures, doping gradients, feature size, dielectric breakdown strength...

Are You Ready for CONELRAD?

CONtrol of ELectromagnetic RADiation (CONELRAD) - RF CafeBefore the Emergency Alert System (EAS) was activated on January 1, 1997, which followed the August 5, 1963 activation of the Emergency Broadcast System (EBS), there was the 1951 implementation of the CONtrol of ELectromagnetic RADiation (CONELRAD). Born out of the Cold War era, CONELRAD was devised in order to not just provide timely forewarning of enemy nuclear and/or bomber and/or submarine-based attacks, but also to silence all commercial broadcasters whose transmitting installation could potentially be exploited as homing signals for the aforementioned bad guys. The Germans had used just such a scheme during the recently concluded...

Hallicrafters: Here's to a Good Old Fashioned Christmas

Hallicrafters: Here's to a Good Old Fashioned Christmas, January 1942 QST - RF CafeAs was customary for U.S. businesses, Hallicrafters ran a Christmas advertisement in the January issue of magazines where they appeared. The January edition, as is common even now, is typically mailed in early December, getting it in the hands of readers in time for Christmas. This "Here's to a Good Old Fashioned Christmas" (which many state governors want to end beginning this year) message appeared in the January 1942 issue of QST magazine. Halli(gan) and (hand)crafters was founded in Chicago in 1932 by William J. Halligan. The company designed and manufactured radio equipment for hobby, commercial, and military applications and quickly became very popular amongst their users...

China Bans Exports to U.S. of Ga, Ge, Sb over Chip Sanctions

China Bans Exports to U.S. of Ga, Ge, Sb over Chip SanctionsGuess we'll just need to start mining our own again, and stop exporting our technology to them: "China announced Tuesday it is banning exports to the United States of gallium, germanium, antimony and other key high-tech materials with potential military applications, as a general principle, lashing back at U.S. limits on semiconductor-related exports. The Chinese Commerce Ministry announced the move after the Washington expanded its list of Chinese companies subject to export controls on computer chip-making equipment, software..."

Postwar Citizens' Radio

Postwar Citizens' Radio, May 1945 Radio-Craft - RF CafeFor the last two centuries our wars have been fought to secure freedom from oppressive regimes, either for our own citizens or for citizens of allied countries requesting our assistance. In the entire history of the United States, no land has ever been claimed during or after the conclusion of the conflicts. Although the human cost has been tragic - especially for those who have lost family members or suffered injuries - one undeniable benefit has been the advancement of technology. "Necessity," it has been said, "is the mother of invention." World War II resulted in significant advances in wireless communications, and the civilian radio industry was quick to exploit the new devices and methods. Futurists wasted no time prognosticating about how the postwar technology world would shape up, and of course radio figured significantly into the vision. This 1945 article from Radio-Craft magazine is an early example...

Please Thank Empower RF for Their Support

Empower RF Systems - RF CafeEmpower RF Systems is the technological leader in RF & microwave power amplifier solutions for EW, Radar, Satcom, Threat Simulation, Communications, and Product Testing. Our air and liquid cooled amplifiers incorporate the latest semiconductor and power combining technologies and with a patented architecture we build the most sophisticated and flexible COTS system amplifiers in the world. Solutions range from tens of watts to hundreds of kilowatts and includes basic PA modules to scalable rack systems.

News Briefs

News Briefs, July 1962 Radio-Electronics - RF CafeAmongst the noteworthy items announced in the July 1962 "News Briefs" column in Radio-Electronics magazine was the impending end of the DoD's CONELRAD early warning defense system. It was being replaced with the Emergency Broadcast System in 1963, which was later replaced by the Emergency Alert System in 1997. Changing names for essentially the same service was - and remains today - a shining example of government waste. Westinghouse debuted its slow-scan TV system for transmitting still images via telephone wires - sort of an early Internet means of downloading pictures that could be stored on magnetic tape...

Remler Model No. 36 6-Tube Dual-Wave Auto-Radio

Remler Model No. 36 6-Tube Dual-Wave Auto-Radio Radio Service Data Sheet, September 1935 Radio-Craft - RF CafeInstalling commercial broadcast radio receivers in cars and trucks was a big deal in the 1930s - even bigger than having one in your home. Having an ability to receive the popular shortwave bands was a real sign of success (as was merely owning a car). An advantage to auto radios was not needing an AC-to-DC rectification circuit like in-home models that required at least one additional vacuum tube and a hefty transformer - although many people in non-electrified rural areas had DC radios in their homes as well (the Rural Electrification Act wasn't passed until 1936). In its service instructions, Remler suggested to owners that if poor reception was experienced, the auto should be parked somewhere that a 50-foot secondary aerial couldn't be deployed. I could locate any examples of restored...

After Class: Power Transformers & Electrostatic Speakers

After Class: Power Transformers & Electrostatic Speakers, August 1955 Popular Electronics - RF CafeBasic transformer circuits have not changed in the more than sixty years since this article was published in Popular Electronics magazine. The applications have definitely changed, though, since active circuits of the day required a relatively low voltage (step-down) for vacuum tube cathode heaters, and at least one relatively high voltage (step-up) for biasing the tube plate. Most transformers for today's consumer applications perform a single step-down operation for 3.3 V, 5 V, 12 V, etc. In many applications, transformers are done away with altogether in favor of solid state rectifiers and regulators. A 5-question quiz is provided at the end. There is also a short tutorial on electrostatic speakers and some analog and digital signal info. Digital circuits were still a relatively new (and scary) concept to most people at the time...

Building Your Own Audio Frequency Choke Coils

Building Your Own Audio Frequency Choke Coils, October 1932 Radio-Craft - RF CafeOne very satisfying aspect of 'rolling your own' audio frequency coils (aka chokes, aka inductors), is how well the simple inductance equations match measured end results. Unless you really manage to mangle the job, if you use the right equation and are reasonably careful to observe wire size, spacing (including insulation), and core diameter, you will be amazed at how close practice matches theory. Although strictly speaking audio frequencies run from a few Hertz up to maybe 15 kHz for people with really good hearing. My experience is that similar success can be had even into the low MHz realm with just a little tuning required. It's not until you get into the realm of self-resonance that everything starts falling apart with basic equations...

Hugo Gernsback on Radio Astronomy

Radio Astronomy, March 1953 Radio-Electronics - RF CafeHugo Gernsback wrote this editorial about the state of the art of radio astronomy in a 1953 issue of his Radio-Electronics magazine. He cites Dr. Jansky's discovery of radio frequency signals emanating from the center of our Milky Way galaxy, and the subsequent work done by radio astronomers in the interim. Little did Gernsback know that a mere decade later later, Bell Telephone Labs engineers Dr. Wilson and Dr. Penzias would serendipitously discover, using the company's "sugar-scoop" antenna, the ubiquitous cosmic microwave background radiation (CMBR) believed to be a signature of the "Big Bang" era. He predicted that, as is true for most realms of theoretical research, much collateral technology would be created as a result. Ultra low noise, cryogenically cooled receivers are an obvious example...

Editorial: Money in Radio Gadgets

Editorial: Money in Radio Gadgets, February 1933 Radio-Craft - RF CafeListen to this on the RF Cafe Podcast. Substitute "cellphone" for "radio" in this title ("Money in Radio Gadgets") and editorial by Hugo Gernsback and it would fit right in with today's market of wondrous gadgetry. Prescient as always, Mr. Gernsback describes in this 1933 issue of Radio-Craft magazine, among other things, what we now refer to as energy harnessing to power ancillary devices and props. He also recommends a scheme for causing 'dancing dolls' on the surface of a table vibrated and mobilized by the sonic waves of a large speaker - a lot like the way years later vibrating football games were made (remember them?) where the men danced randomly across the painted metal playing field. It sounded like a pair of electric hair clippers running...

Engineering & Science Crossword for November 24

Engineering & Science Crossword Puzzle November 24, 2019 - RF CafeFor two decades, I have been creating custom engineering- and science-themed crossword puzzles for the brain-exercising benefit and pleasure of RF Cafe visitors who are fellow cruciverbalists. This November 24, 2019, puzzle has a holiday message for you. A database of thousands of words is used which I have built up over the years and contains only clues and terms associated with engineering, science, physical, astronomy, mathematics, chemistry, etc. You will never find a word taxing your knowledge of a numbnut soap opera star or the name of some obscure village in the Andes mountains. You might, however, encounter the name of a movie star like Hedy Lamarr or a geographical location like Tunguska, Russia, for reasons which, if you don't already know, might surprise you. The jury is out on whether or not this type of mental challenge...

Bell Telephone Laboratories Ad - Coaxial Electron Tube

Bell Telephone Laboratories Ad, Coaxial Electron Tube June 1954 Radio & Television News - RF CafeFor a given semiconductor compound, the maximum operational speed of a transistor is governed pretty much by its gate thickness. Capacitance and impurities along with lithography precision and accuracy are the culprits. Shrinking gate sizes and growing crystals with greater purity has driven operational speeds upward significantly over the years. An equivalent set of issues plagued vacuum tube development a century ago. The physical spacing of grid elements wrt each other as well as to the cathode and plate placed an upper limit on amplification bandwidth. As always, judicious study of the underlying causes led to the development of new designs that, along with improved manufacturing techniques, overcame existing barriers and, also as always, exposed yet a new set of limiting criteria for conquering...

RF Cafe Engineering & src="../miscellany/homepage-archive/2019 Puzzle April 22

RF Cafe Engineering & src=Each week, for the sake of all avid cruciverbalists amongst us, I create a new technology-themed crossword puzzle using only words from my custom-created lexicon related to engineering, science, mathematics, chemistry, physics, astronomy, etc. You will never find among the words names of politicians, mountain ranges, exotic foods or plants, movie stars, or anything of the sort. You might, however, see someone or something in the exclusion list who or that is directly related to this puzzle's theme, such as Hedy...

Space Electronics

Space Electronics, September 1961 Popular Electronics - RF CafeSuccess won in the realm of space-based communications has been fraught with many failures. As with most endeavors, it is thanks to the relative few who have sacrificed and endured against overwhelming odds to bring significant technological advances in communications to the many. Space presents a particularly difficult venue because of the harsh deployment and operational environment, and inaccessibility after deployment. Personal sacrifice has taken the form of depression, financial ruin, lost opportunity for other endeavors, broken families, sickness, substance abuse, and other maladies brought on by an obsession with success. Such sacrifice has built the modern world...

Variable-Voltage Tuning: How It Works

Variable-Voltage Tuning, April 1969 Radio-Electronics - RF CafeHave you ever used any of these voltage-variable capacitor (VVC) types: varicaps, epicaps, minicaps, voltacaps, capistors and varactrons? If you answered "no, but I have used varactor diodes," then the more correct answer would have "yes, I have, but by a different name." Construction was similar for all variations. This article from a 1969 issue of Radio-Electronics magazine reports on some of the earliest forms of diodes specifically designed to use a reverse bias on the PN junction to control the effective capacitance of the device for use in frequency tuning circuits. The first uses were for electronically tuning local oscillators in mixing stages, and then for making tunable filters. Capacitance ratios greater than 10:1 with some VVCs allowed tuning over a very wide range. At the time the article was written, there was not universally agreed upon schematic symbol for the VVC, as illustrated in Figure 2. Varactor-tuned television channel selectors...

Tip for Copying Images from Websites

Editing Image URL for Copy / Paste - RF CafeIn my daily routine of perusing the WWW (World Wide Web - remember that?) for good information to post, I need to copy images into which thumbnail versions are made. A very recent trend has evolved for the sake of mobile device displays which appends some sizing directives to the end of the otherwise normal URL, and that prevents doing a copy and paste with right-click -> Copy Image, and then paste it into a graphics editor. Instead, do a right-click -> Copy Image Location and then paste that URL into your browser. Click the thumbnail image above for an example. Note the appendage after the ".png" file extension:

?auto=format&fit=crop&h=432&w=76"

That prevents the normal Image Copy from working. Delete everything after .png and then hit enter. You should now be able to copy and paste the image into your editor.

RF & Electronics Stencils for Visio

RF & Electronics stencils for Visio r4 - RF CafeWith more than 1000 custom-built stencils, this has got to be the most comprehensive set of Visio Stencils available for RF, analog, and digital system and schematic drawings! Every stencil symbol has been built to fit proportionally on the included A-, B-, and C-size drawing page templates (or use your own page if preferred). Components are provided for system block diagrams, conceptual drawings, schematics, test equipment, racks, and more. Page templates are provided with a preset scale (changeable) for a good presentation that can incorporate all provided symbols...

Bell Telephone Laboratories Advertisement

Bell Telephone Laboratories Advertisement, October 1949 Radio & Television News - RF CafeBell Telephone Laboratories used to run some pretty interesting advertisements in magazines back in the 1940s through 1960s that touted the many communications innovations coming from their scientists and engineers. They built what was indisputably the worlds best, most reliable telephone network. It, along with the Interstate Highway System, is credited for a large part of what fueled America's growth so significantly after World War II. This ad from a 1949 issue of Radio & Television News magazine tells how repairmen used a specially designed sensor to trace out faulty phone lines by listening for a test signal sent out by the central office. What caught my attention about this ad was the uncanny resemblance the man in the photo has to Melanie's father - especially with the ball cap and glasses...

Dots and Dashes, July 1934 Radio News and the Short-Wave

Dots and Dashes, July 1934 Radio News and the Short-Wave - RF CafeIf you read through this "Dots and Dashes" column from the July 1934 issue of Radio News, you will find many familiar topics -- and a couple weird ones. Among the familiar are transmitting electrical power via RF waves, an electronics industry convention and exposition being held in Chicago, elevator control with electric sensors to assure the cars stop at floor level, global communications, the closing of a historic radio station (how 'historic' can a radio station be in 1934?), earth-moon-earth (EME) experimentation, and remote control of beacon stations with radio signals. The weird ones? How about an "electric woman" with glowing breasts and a "queer-acting" radio microphone, do they qualify?...

Resistivity (ρ) & Conductivity (σ) of Metals, Alloys, Rocks, and Soils

Resistivity (ρ) & Conductivity (σ) of Metals, Alloys, Rocks, and Soils - RF CafeI recently created a new reference page titled "Resistivity (ρ) & Conductivity (σ) of Metals, Alloys, Rocks, and Soils." Values for materials are pulled from my copy of Reference Data for Radio Engineers, Sams Publishing. Resistivity, also referred to as specific resistance, is dependent on the nature of the material as well as its volume definition (shape and size). Resistivity is expressed in units that are the product of resistance and length; e.g., Ω·cm. As an example of calculating a volume's resistance, consider the drawing to the left. Assume 12 AWG copper wire with a resistivity of 1.72x10-6 Ω·cm, a cross-sectional area...

Mac's Radio Service Shop: Intermittents Still Pursue

Mac's Radio Service Shop: Intermittents Still Pursue, February 1949 Radio & Television News - RF CafeMac McGregor, owner of Mac's Radio Service Shop, can always be counted on to provide his apprentice technician, Barney, with a lesson from his own life-long attendance at the School of Hard Knocks. Barney is your stereotypical young buck whose level of seriousness needs occasional alignment, just as do the radio and television sets he services. In this episode, I can't find where Mac actually solved the intermittent electrical condition believed to be causing the problem - weird. The "Mac's Radio Service Shop" series ran in Radio & Television News magazine for many years prior to a similar electronics story series called "Carl & Jerry" that appeared in Popular Electronics. Both were created by consummate storyteller John T. Frye.

Engineering Theme Crossword Puzzle for August 8th

Engineering Theme Crossword Puzzle for August 8th, 2021 - RF CafeThis Engineering Theme crossword puzzle for August 8th, 2021, contains only words and clues related to engineering, mathematics, chemistry, physics, and other technical words. As always, this crossword contains no names of politicians, mountain ranges, exotic foods or plants, movie stars, or anything of the sort unless it/he/she is related to this puzzle's technology theme (e.g., Hedy Lamarr or the Bikini Atoll). The technically inclined cruciverbalists amongst us will appreciate the effort. Enjoy!

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

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. Most Hams do their part from home-based "shacks" while others join in during Hamfest gatherings. Some adventuresome and hardy souls set up temporary (and sometimes fixed) stations in remote locations around the world in order to provide rare and exotic contact opportunities, where coveted QSL cards can be collected...

What Ground?

What Ground?, August 1967 Popular Electronics - RF CafeEstablishing a good ground connection is more important than ever with all the vulnerable electronics devices connected to house wiring for the Internet of Things (IoT). The old saying of "Ground is ground the world around" is only true if you actually have a good path to that ground potential. This article discusses methods for determining whether or not you have a low resistance ground interface, and how to establish one if needed. However, that is only the below-grade part of the equation [ground rod(s) and possibly conduction-enhancing chemicals]. Installing a low resistance and equally important low inductance path above grade to the below grade component(s) is essential for maximum protection. Lightning is a transient phenomenon, so the di/dt part of the v(t) = L * di/dt equation governing voltage across an inductor...

A New Antenna Rotor

A New Antenna Rotor, January 1960 Electronics World - RF CafeAt the end of the last century (the 20th), aside from the impending total collapse of the world's electrical infrastructure due to Y2K computer date issues, technovisionaries (a word I just made up) predicted the near-term demise of local over-the-air (OTA) broadcasting of both commercial radio and television. Cable and satellite was going to supplant it all. For a short while things seemed to be going that way, particularly as both forms of media (radio and TV) began being available via smartphones. The FCC (Federal Communications Commission) was so sure OTA television was dead that it wanted to reallocate unused spectrum (white space) for other uses. It also mandated a conversion of all TV broadcasting to be done in digital form. The plan forced either trashing of existing television sets and purchase of new models or the purchase of analog-to-digital conversion boxes. The compliant public folded like a cheap suit...

Theory and Application of UHF

Theory and Application of UHF, December 1944 Radio News - RF CafeThis is part 8 of a series authored by Milton Kiver entitled, "Theory and Applications of UHF," that appeared in Radio News magazine in the mid 1940s. As you might expect it is a very extensive delve into the relatively new realm of UHF generation, transmission, propagation, and reception. You might not know that up through the 1930s, UHF circuit and practice had been relegated to the amateur radio operators because those frequencies from 300 MHz to 3 GHz were considered too unexploitable for professional use. It was not until Hams did the hard work of figuring out practical methods of building circuits and antennas and characterizing geographical and atmospheric conditions that affected propagation that suddenly industry and government decided UHF might be useful after all...

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