Homepage Archive - March 2026 (page 2)

Tuesday the 31st

How to Use Imaginary Operator "j"

Complex numbers have served the function of weeding out prospective electronics technician and electrical engineer degree-seeking people for a long time. I do not recall ever seeing such a beast until taking college courses. In high school and USAF tech school, we calculated reactive circuit parameters using well-established formulas that already accounted for the "imaginary" part of complex impedance. You can only go so far with circuit analysis without complex number math, though. All of the electronics magazines at some time (often every couple of years) ran articles introducing readers to the manipulation of the real and imaginary parts of reactive impedance. I have posted many of them here on RF Cafe...

Crosley "Fortyfive" Tabletop Radio Advertisement

According to the Bureau of Labor Statistics' Inflation Calculator, this Crosley "Fortyfive" tabletop radio advertisement appearing in a 1932 issue of Radio-Craft magazine which was priced at $45 (which coincidently happened to be the name of the model) at the time would cost more than a kilobuck in 2025 dollars. That's a lot of money for a tabletop radio - even for a fine quality floor model console - but after all it was a newfangled superheterodyne model containing seven vacuum tubes. The superhet feature made tuning a lot easier since baseband filters could remain fixed. Cheaper models were available at about half the price, but even that was a lot of dough to lay out for entertainment. Radios were considered a luxury item - like a third car is today...

High-Speed Trapped-Light Photodetector

"A new ultrathin photodetector captures light across the full spectrum in just 125 picoseconds, opening the door to faster, smarter imaging technologies. Engineers at Duke University have b

uilt the fastest pyroelectric photodetector ever demonstrated, a device that senses light by capturing the heat it produces when absorbed. This ultrathin sensor can detect light across the entire electromagnetic spectrum. It runs at room temperature, requires no external power, and can be integrated directly into on-chip systems. The technology could lead to a new generation of multispectral cameras with applications in skin cancer..."

Stenode's Selectivity Revolutionary

By the early 1930s when this Stenode vacuum tube article appeared in Radio-Craft magazine, commercial broadcast stations were still working out what would be the best combination of channel bandwidth and spacing to enable a maximum number of adjacent transmissions while achieving sufficient selectivity to enable acceptable reception. 5 kHz was deemed reasonable to reproduce the human voice as well as musical instruments. An accompanying 10 kHz channel separation (still in effect today) was adopted to accommodate upper and lower sidebands that amplitude modulation creates. Interestingly, if you read carefully, the Stenode's high level of selectivity, made possible by an integrated crystal, was intended to remove modulation sidebands and thereby significantly narrow the required bandwidth...

Six-Inch Radio Waves

2.1 GHz (5.6-inch, or 14 cm wavelength) radio waves were an almost totally unexplored realm in 1930, with it and higher frequencies being the domain of theoretical research laboratories. Signals generators capable of producing much more than a few hundred megahertz were rare even in commercial applications. As reported here, centimeter-length electromagnetic waves were "according to the theories of Barkhausen and Kurz, [the] result of purely electronic vibrations, whose frequency was determined only by the operative data of the tube and was not dependent on any internal or external oscillation circuit." A half-wave receiving antenna picked up the transmitted signal with a simple diode detector to enable, after a couple...

Many Thanks to Anatech Electronics for Long-Time Support!

Anatech Electronics (AEI) manufactures and supplies RF and microwave filters for military and commercial communication systems, providing standard LP, HP, BP, BS, notch, diplexer, and custom RF filters, and RF products. Standard RF filter and cable assembly products are published in our website database for ease of procurement. Custom RF filters designs are used when a standard cannot be found, or the requirements dictate a custom approach for your military and commercial communications needs. Sam Benzacar's monthly newsletters address contemporary wireless subjects. Please visit Anatech today to see how they can help your project succeed. 

Monday the 30th

Parfum Elektronique

<-- This is the colorized and enhanced AI-generated version of one of the drawings in the story. John Frye routinely used his Carl and Jerry column in Popular Electronics magazine to mix various assortments and portions of science, humor, adventure, ham radio, and human nature in what I have dubbed a technodrama. Sometimes the topics are a little off-beat, as with this "Parfum Elektronique" story - that's French for "Electronic Perfume," although you probably already guessed that. The pair of high-school-aged electronics experimenters enlisted the assistance of classmate Norma, a babe who often agreed to help them with boy-girl relationship pranks, to try out their odor-producing contraption. Integral in Mr. Frye's lesson is that there are seven categories of odors...

Oldest Electronics Companies Crossword

This week's engineering crossword puzzle features the names of some of the world's oldest electronics companies. Many of them began life with a primary business focus other than electronics, then ended up being known universally for their high tech products. If you're like me, until now you had no idea that one of the world's leading cellular equipment makers originally was a wood pulp mill, and another made playing cards. Clues with asterisks (*) are the featured companies...

GaN: Hybrid Structures, HEMT, Substrates

"This article series on gallium nitride (GaN) fundamentals described crystal structures and the formation of the two-dimensional electron gas (2DEG), along with material figures of merit and the transition from depletion-mode to enhancement-mode GaN HEMTs. Part 2 will outline hybrid structures and the RDS(on) penalty, as well as provide further details on GaN HEMTs and substrate choices for GaN. It will also make the case for the path to monolithic integration while showing how ohmic contacts, metallization, and packaging advantages are facilitating this design roadmap. An alternative to monolithic enhancement-mode GaN transistors is the hybrid cascode..."

Simple Radio Mathematics for the Service Man

Included in this first of a series of the "Simple Mathematics for the Serviceman" articles that ran in Radio-Craft magazine is another "cheat sheet" full of oft-used formulas. It begins with basic Ohm's law, resistance, inductance, and capacitance, then builds from there. What was valid in 1930 is still valid in 2022. Prior to a smartphone in every pocket, notes were pinned to a lab wall or kept in a hand-written notebook...

432-Mc. Solar Patrol

NASA (and its predecessor NACA), and private and public operators have been monitoring solar events in the optical realm for many decades while attempting to correlate terrestrial phenomena with it. Auroral light displays in the extreme polar regions have long been known to be caused by solar flare and coronal mass ejections (CME). With the advent of radio, the electrical nature of the upper atmosphere became evident when static (AM) and long range propagation affected long range communications. Extreme CME activity eventually was associated with behavior of the electrical power grid; indeed, massive blackouts and brownouts are to blame for many. Last but not least came concern for sun-sourced electrons regarding satellites...

Friday the 27th

Antennas for Satellite Reception

This 1958 Popular Electronics magazine article provides practical instructions for constructing high-gain antennas to receive 108 MHz satellite signals, detailing four designs ranging from simple folded dipoles to complex Yagi arrays. The author emphasizes that success requires precise impedance matching, careful orientation, and weatherproofing, often utilizing modified television hardware to capture weak transmissions from early space vehicles. While the fundamental RF physics of signal gain and directivity remain unchanged, "listening" to satellites today has shifted from manual, labor-intensive construction of metal arrays...

Men Who Have Made Radio - E. F. W. Alexanderson

The name Ernst Frederick Werner Alexanderson (1878-1975) might not seem overly familiar to you, but he is credited with designing the first high frequency alternator for transmitting longwave audio modulation over long distances. His device preceded the spark and arc type transmitters that infamously spewed harmonics and noise all over the spectrum and were therefore a great nuisance when broadcast at high power levels. It was a relatively (for the time) narrowband scheme that permitted more stations to be co-located in a given service area. He went on the develop one of the first successful television projectors as well. Read a short biography on Mr. Alexanderson in the "Men Who...

ARRL Is Hiring!

The National Association for Amateur Radio® (ARRL) is seeking talented individuals to join our team and help advance the Amateur Radio Service. We are currently hiring for several impactful positions: • RFI Lab Engineer Support ARRL's mission to protect and enhance spectrum access by managing and resolving Radio Frequency Interference (RFI) cases • W1AW Station Manager This is a rare opening and exciting opportunity to lead operations at W1AW • Public Relations & Outreach Manager • Awards Program Supervisor • Development Associate • IT Support Specialist • Logbook of The World Support Associate • Membership Manager...

Visions of 1946

December is traditionally the issue for magazines to sum up accomplishments of the ending year and make predictions for the next year. Radio-Craft magazine was no exception, but in 1936 they went ten steps farther and prognosticated a decade into the future - all the way to 1946! It is actually a tongue-in-cheek reprint from Pathe News magazine. However, note the drawing of "professor teaches 2 million pupils," where he is instructing via television and the railroad company boss checking in on the conductors en route via wireless teleconferencing. It might have seemed like a pipe dream in 1936, but now it is commonplace. Not only do we now have live classroom broadcasts, but millions of YouTube videos of instruction for performing...

Mac's Service Shop: Automation and the Technician

Once transistorized computers made desktop-sized systems a reality, the sure eventuality of humans being replaced by their electronic equivalents became a popular theme of media pundits. News reports and "special features" on TV at the same time scared citizens concerned for their jobs and assured them that by the year 2000, humans wouldn't need to work anymore anyway because computers and robots would be doing everything for them. The millennium crossover occurred a quarter of a century and a half ago, and looking back it is true that computers and robots have usurped a lot of what used to be done manually, but, as Mac presciently predicts in this story...

Thursday the 26th

Talent Hunt Unearths Junior Scientists

You have been warned not to believe anything you see, hear, or read anymore, because of the ability of AI (artificial intelligence) to alter and/or create just about anything. I offer in support of that thesis the two photos shown here. The black and white image was scanned from a 1958 issue of Popular Electronics magazine. I fed it exactly as shown to Gemini 2.5 Flash, along with these simple instructions: "Please clean up the 1958 magazine photo to remove noise, sharpen, and colorize it." You see the result. The AI beast not only perfected the picture, but interpreted its content (an amateur cyclotron, per the article) as a science laboratory scenario and added the appropriate background. Yikes!

Radio Set Prints Newspaper!

Writing about "outdated" methods of radio-based facsimile machine implementation in 1934 seems a bit incredible considering how relatively new both technologies were at the time. Nevertheless, Radio-Craft magazine editor Hugo Gernsback reported on the new era of fax machines that were on display at the 1933 World's Fair in Chicago. Of course fax machines of that time were not exactly desktop models that could be located in a corner of your office or cubicle (not that cubicles were common). If you substitute transistors for vacuum tubes, stepper motors for simple DC motors and solenoids, and solid state lasers and LEDs for incandescent light sources, the fundamentals have not...

ARRL Field Day 2026

"It's not too early to gear up and get ready for ARRL Field Day! Field Day 2026 takes place June 27 – 28 and will bring together more than 30,000 amateur radio operators for one of the most popular on-the-air events in the US and Canada. This year's Field Day theme is 'Amateur Radio: A National Resource.' Combined with the ARRL Year of the Club, it provides the perfect opportunity for radio clubs to set up stations in public places to demonstrate ham radio's science, skill, and service to our communities and our nation. All of the information you need to get started..."

Radio à la Cortlandt Street!

New York City has forever, it seems, been the place to be for street vending. A famously large pedestrian populace creates an ideal venue for hacking goods of all sorts to passers-by. A phenomenon in radio was created in the early 1930s with the rapid advances in technology and high volume manufacturing techniques, coupled with increasingly efficient transportation of goods on interconnecting roadways and delivery trucks. The photos included in this Radio-Craft magazine story illustrate the level of enthusiasm by the public for radio. A plethora of replacement components for repairing malfunctioning sets and for scratch-built sets at fantastically low prices helped fuel the fire. An offer of "aluminum chassis" with pre-punched and drilled holes was really surprising not because of the holes, but for...

Wireless Engineering Crossword Puzzle

This week's Wireless Engineering crossword puzzle contains the usual collection of science, math, and engineering terms. Also included are a couple topics that have been in the technical news headlines lately and the names of two new companies advertising on RF Cafe. 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., Reginald Denny or the Tunguska event in Siberia). The technically inclined cruciverbalists amongst...

Wednesday the 25th

Operation Blub

Once again, the undaunted, indefatigable husband of "friend-wife" - maybe even the alter ego of story-teller and artist Carl Kohler - embarks on another grand and glorious electromechanical project, always meeting with near - but never total - success. This time around, the subject of his passion is a giant radio-controlled model cruiser. In the 1950s and 1960s, the great size of such a boat was perfect for the great sizes of model engines and model R/C systems. Vacuum tubes and rather large, leaded resistors and capacitors comprised the electronics of both transmitters and receivers, and at least two batteries were required for power...

Glass-"Metal" Tube Shield

While working on vacuum tube based USAF air traffic control radar and radio systems, and having seen many tube television and radio sets I never recall seeing one of these form-fitting metal shields. All the ones I've seen are simple cylinders that slide over the tube and either twist into a receiving rim slot or they have spring metal fingers that grab the glass envelope. As you might guess, utilizing a metal shield around a tube for anything other than a low frequency application like an audio amplifier or poser supply requires circuit design that takes into account the capacitive effects of the large metal plates...

DAVINCI Venus Mission Ceramic Sensor

"Venus is often described as Earth's twin, but that comparison quickly falls apart at the surface. With temperatures hot enough to melt lead and pressures that rival the deep ocean, Venus's harsh environment has required NASA and other space agencies to orbit the planet, studying it remotely while sustained surface exploration has remained elusive. ​If NASA intends to deploy landers capable of operating for days or even weeks on Venus, it must rely on a fundamentally different class of sensing and control systems. Exploration would require high-temperature ceramic sensors built from wide-bandgap materials and advanced structural ceramics..."

Measuring Distortion in Audio-Frequency Amplifiers

As with so many topics, the basics of topics like harmonic distortion (and other forms of distortion) in an amplifier circuit has not changed much - if at all - over the decades. Test equipment and circuits being measured get more advanced, but, especially if you are new to the concept, articles like this one on audio-frequency distortion from a 1941 edition of Radio-Craft magazine are as useful today as it was when it was written. When studying, in particular, harmonic distortion, having a knowledge of the Fourier series for common waveforms like triangle waves, sawtooth waves, square waves, and even a semi-circle- shaped wave is especially enlightening since it explains a lot of waveform shapes where harmonics are present...

A Stationary Reversible Beam

A vertical antenna can have a significant advantage over a horizontal antenna from a maintenance perspective, since, depending on how high the antenna is mounted off the ground, the "business end" where electrical connections are made are more accessible. The configuration shown here would be difficult to implement if a mast rotator is to be used because of the stabilizing guy wires on the lower frame. Although it should be possible to achieve the necessary rigidity without guys by using an aluminum or fiberglass tubing frame rather than wood, preventing weathervaning in strong winds could prove difficult. A nifty feature of this "reversible beam" antenna is that reciprocal directivity is implemented simply by swapping out a short...

Tuesday the 24th

What the Sputniks Said

A 1958 report in the Russian journal Radio detailed early scientific findings from Sputnik I and II, marking a significant advancement in space-based electronics. Analysis of Sputnik I's radio transmissions revealed complex propagation patterns, including refraction and reflection off the ionosphere's F2 layer, which allowed signals to travel far beyond direct visibility and occasionally produce a round-the-world echo. These observations provided researchers with critical data regarding how radio waves behave in relation to atmospheric layers and satellite positioning. Furthermore, the article discussed findings from Sputnik II concerning solar radiation intensity beyond the earth's atmosphere. The researchers utilized actinometry - the science of measuring electromagnetic radiation, particularly solar radiation...

An 18 Metal-Tube All-Wave Superhet

As I have written in a couple articles recently, there was a huge push in the mid 1930s to adopt the revolutionary new metal-encased vacuum tubes over established glass-encased tubes. Today, interest in vacuum tube amplifiers is building among audio enthusiasts both from a nostalgic perspective and from a long-perpetuated belief that sound from vacuum tube circuits have a distinctively richer quality than that of solid state devices. I post this stuff for the benefit of those who otherwise might not be able to find the information otherwise. Your patience indulgence is appreciated...

Utilities Prepare for Drone Attacks

"In the fictional nation of Beryllia, the 2026 World Chalice Games were set to begin as the country faced an unrelenting heat wave. The grid, already under strain from the circumstances, was dealt a further blow when a coordinated set of attacks including vandalism, drone, and ballistic attacks by an adversary, Crimsonia, crippled the grid's physical infrastructure. This scenario, inspired by the upcoming 2026 World Cup and the 2028 Olympic Games in Los Angeles, was an exercise in studying how utilities can prevent and mitigate, among other dangers, physical attacks on power grids..."

WMC-2-18-15dB-S Coupler for 2-18 GHz

Werbel Microwave began as a consulting firm, specializing in RF components design, with the ability to rapidly spin low volume prototypes, and has quickly grown into a major designer and manufacturer. The WMC-2-18-15dB-S is a directional coupler that covers 2-18 GHz with a flat response over the band. Features 15 dB coupling response with broadband flat coupling response, high directivity, and excellent return loss performance. Coupling flatness ±0.35 dB typical. Insertion loss 0.8 dB typical. Directivity 17 dB typical. "No Worries with Werbel!"

A New English All-Metal Tube

The saga continues... Please bear with me even if you have no interest in the much-hyped (at the time) history of the advent of all-metal vacuum tubes in the mid 1930s. They were predicted to make glass-encased tubes obsolete. It never happened. Believe it or not, there are a few folks out there (like moi) who like reading about the history. Posting this on the RF Cafe homepage helps the search engines find and register it faster. If you also happen to care, then you might be interested to know this article was...

Radio-Radar-Sonar in Naval Applications

World War II was the "necessity" that elicited the "mother of invention" activity responsible for many huge leaps in technology - not the least of which was electronic verbal and non-verbal communications. Along with radio and radar, Loran had become a major means of ocean and air navigation. A fair description of the operational details, including timing diagrams, is included in the text. Loran-A, the original system as it came to be known, was fully decommissioned in 1980, thereafter supplanted by Loran-C. With the advent of GPS, Galileo, and Glonass navigation systems and their low and their low equipment and installation costs...

Monday the 23rd

Carl and Jerry: Whirling Wheel Magic

In this 1960 Popular Electronics magazine adventure, teenage inventors / hobbyists Carl and Jerry explore the mechanics of Space Inertial Reference Equipment (SPIRE), a sophisticated navigation system using gyroscopes, pendulums, and clocks to track position autonomously. Inspired by a television program featuring Dr. Charles S. Draper, Jerry demonstrates how a gyro-stabilized platform maintains spatial orientation regardless of external movement. The duo soon applies this scientific knowledge to a practical mystery when a local factory manager seeks their help in catching an employee stealing expensive alternators. By placing a timer-controlled, battery-operated gyroscope inside a bait package, they successfully trap the thief. As the culprit exits the factory, the activated gyroscope creates unexpected torque during a turn, causing the lunch box to move erratically and reveal the stolen goods. The story concludes with the boys reclaiming their device, leaving the factory manager delighted by his opportunity to experiment with the powerful "toy." This plot is a lot like "The Hot Hot Meter" story.

Microwave & RF Engineering Crossword Puzzle

This week's Microwave and RF Engineering crossword puzzle contains the usual collection of science, math, and engineering terms. Each week for more than two decades I have created a new technology-themed crossword puzzle using only words (1,000s of them) 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, find someone or something in the otherwise excluded list directly related to this puzzle's technology theme, such as Hedy Lamarr or the Bikini Atoll, respectively. Avid cruciverbalists amongst us: the gauntlet has been thrown down.

GaN-on-Silicon HEMTs for mm-Wave 5G

"Researchers based in Singapore and Belgium have reported record high peak power-added efficiency (PAE), of more than 60%, for moderately scaled gallium nitride (GaN) on silicon (Si) high-electron-mobility transistors (HEMTs) at 30 GHz operation. At the same time, the devices perform with state-of-the-art noise figures (NFs) as low as 1.1 dB. 'These results suggest that moderate scaling could deliver competitive GaN-on-Si HEMT technology, when combined with optimized epitaxial structure and process..."

Signal Splitting Pads

Designing resistive impedance-matched signal splitting networks is nowadays mostly done with the assistance of computer software. In fact, odds are pretty high that the designer either has no idea what the formulas behind the "magic" are, or at least it has been a very long time since working them with pencil and paper. There's no shame in that, though, just as there is no reason to expect someone using a cellphone must know the intricacies of the internal circuits or the network to which it is connected. We've moved past that. For those of us who still appreciate a refresher on the behind-the-scenes calculations being performed at lightning speed...

Listening to the World

During and immediately following World War II, the "Monitoring Service" of the British Broadcasting Corporation (BBC) relentlessly listened to radio broadcasts from all over the world in order to be able to break headline news and, if appropriate, pass strategic military information on to Allied command centers (who were simultaneously doing their own monitoring). This article tells of some of the more significant messages intercepted and how the facility was a highly guarded secret in order to prevent sabotage and infiltration. At the height of activity, 32 languages were being transcribed into English daily, consisting of more than...

Friday the 20th

Familiar Farces - by Carl Kohler

We have all known at least one of these guys in our lives. Truth is, some of us - myself included - might have been considered to be one (or more) of these guys by someone else at some time. Carl Kohler produced these kinds of comic/real-life pieces for Popular Electronics magazine for many years. They usually featured a technohobbyist husband frustrating his mostly-accommodating wife (aka "wife-friend") with wild-haired inventions and projects. I am always open to someone else offering an idea or opinion, so long as it is not delivered in an obnoxious manner. On more than one occasion, a person without even specific technical knowledge will toss out a great idea that had not occurred...

RF Cafe Website Categories Crossword Puzzle

OK, I admit that this week's crossword puzzle is a little self-serving and self-promoting, but what the hey. All of the clues with an asterisk (*) after them are categories in the table of contents at the tops of RF Cafe website pages, so that should help a bit. To make it even easier, they are all on the "Main" TOC menu. 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!

Working Motor from Multimaterial 3D Printer

"Most 3D printers are designed to produce plastic parts, such as prototypes, housings for electronics, or decorative objects. Building a working electric machine is far more complicated. Unlike a typical plastic print, devices like motors need different regions to do different jobs: some conduct electricity, others insulate it, some generate or guide magnetic fields, and others provide structural support or flexibility. In a paper published last month in Virtual and Physical Prototyping, the [MIT] group introduced a multimaterial 3D-printing system capable of producing a working electric linear motor in about three hours. The platform processes five functional materials used in the printed motor..."

Checkers by Radio

Game playing with a remote opponent is routine these days thanks to the Internet, but a couple decades ago it was not quite so easy. A checkers or chess match via telephone, snail mail, or even fax machine were the venues available to the common man, but Hams had another means - radio! Using either Morse code or voice and a playing board set up like the one shown in this article, two players could easily match wits anywhere in the world where signals could be exchanged. Evidently the participants could get so wrapped up in the game that they risked forgetting to broadcast their call signs at the legally required interval (every 10 minutes), so author Utterback provides a friendly...

FM Broadcast Licenses Issued to First 15 Stations

This edition of National Radio News announces the FCC's approval of the first 15 FM broadcast licenses for stations spread across the country. It is also the first issue following America's entrance into WWII and includes a question from a Ham regarding whether simply listening to radio reports was allowed. As you might know, the FCC prohibited amateur radio operators from transmitting for any reason during both World War I and World War II. The reasons given were clearing the airwaves to make monitoring easier, to prevent intentionally encoded messages from being sent, and to keep homeland status information from being broadcast. Homeland status could be ascertained by assimilating reports of who was being drafted and entering service and...

Thursday the 19th

The Stabistor Diode

The Stabistor, a specialized semiconductor device introduced in the 1960s, functions as a voltage-dependent switch that remains an open circuit until its specific "break over" voltage is reached, at which point it conducts current effectively. Popular Electronics magazine highlighted its versatility, showcasing practical circuits for sensitive meter overload protection, linear temperature-sensing bridges, signal volume compressors, noise-squelching limiters, and voltage regulation. By utilizing the forward conduction characteristics of silicon junctions, the Stabistor provided a cost-effective alternative to more complex components of the era. Despite its utility, the Stabistor is largely obsolete today...

An Automatic Program Censor

The effort to block advertising on radio broadcasts has been going on for about as long as advertising has been in use, as evidenced by this 1934 article in Radio-Craft where a 'robot' advertising silencer' device is presented for removing "superfluous advertising." Headlines from a few weeks ago announced Apple's program for blocking ads that appear on websites, causing a big to-do about how all the "free" content would be jeopardized since it is the advertisers who pay for the music and other programming to be delivered to the user. Without the convenience and economy of software to do the job in 1934, however, fairly complex discriminator circuits were used to detect and mute the 'garrulous announcer or advertiser' between regular programming. It's pretty funny to...

Will Satellite D2D Work Indoors?

"Direct-to-device (D2D) satellite services were to the fore at Mobile World Congress 2026 in Barcelona. One of the main questions that remain, however, is how well they will work indoors. Starlink talked about their version 2 satellites at the show. Starlink and AST SpaceMobile must prove whether satellite services can actually offer service indoors. The indoor question Some industry analysts are still unconvinced by the possibility of indoor satellite data and cell offerings..."

Space Demand Rising for Next-Gen TVAC Testing

TotalTemp Technologies maximizes our combined 40 years of experience in this highly specialized field to create new, alternative, "Next Generation" temperature chambers and temperature testing equipment. In order to best serve our customers, TotalTemp Tech publishes a technical Blog where our designers post informative articles on the industry and our unique products. A new blog post has been added titled "Space Demand Rising: Powering up with Next-Gen TVAC Testing," wherein is discussed the growing need for efficient, small-scale thermal vacuum (TVAC) testing equipment as the U.S. space economy expands toward 2026. Key Takeaways Include: Market Drivers: Increased activity from NASA, the Space Force, SpaceX, and global satellite initiatives...

An Inside Story About Metal Tubes

The advent of metal-encapsulated vacuum tubes was supposed to be the death knell for traditional glass tubes. This 1935 article from Radio-Craft spelled out the many virtues of 'metal' tube and how in short order their superiority would obviate the need - even desire - for "glass" tubes. I'll let you read the article for the details, but want to make note of an evidently archaic term used that could potentially be really popular in today's manufacturing world if duly resurrected - "quantiquality" (aka "quanti-quality" or "quanti quality"). The connotation is a process of high quantity in conjunction with high quality. The only references I could easily find to quantiquality was from late-19th-century newspaper archives. If sometime within the next few years you start seeing some...

Wednesday the 18th

Replacing Underground Service Cable and Breaker Panel

If you have been an RF Cafe website visitor for a long time, you might recall back in 2010 when I posted How an Electrical Engineer Spends "Vacation." It showcased the extensive electrical wiring I did on my daughter's horse riding business. A few years ago, she and her husband, a major in the USANG, moved to an old former diary farm property. The buildings are old and dilapidated, but we are slowly patching and improving them. Earlier this month, the new submersible pump we just installed late last summer stopped working. When I measured the panel bus voltage, one leg read 120 V, and the other leg was at about 70 V. Turns out the current that would normally be supplied by the other 120 V leg was being supplied in series with the submersible pump motor. This task was within my purview. Having performed many electric service heavy-ups..

New Batteries: Progress or Confusion?

Battery technology experienced a major technology evolution in the late 1950s similar to the one that took place in the late 1990s. Prior to the 50s, most common portable batteries were of the carbon-zinc type and were not rechargeable. Nickel cadmium (NiCad) cells existed, but were not in widespread use largely because little was known about the chemistry and how it responded to various charge and discharge cycles. Mercury, NiCad, nickel metal hydride (NiMH), alkaline-manganese, began gaining popularity in applications requiring longer battery life and more consistent discharge characteristics. In the 2000s, lithium polymer (LiPo) and lithium ion (LiIon) underwent a similar evolution. Still, all the aforementioned battery types are in use today...

High-Density PCBs Without Bigger Boards

Since 2005, San Francisco Circuits has been a trusted U.S. provider of advanced PCB manufacturing and assembly solutions for R&D innovators, prime contractors, and integration experts. Double-Sided Ball Grid Array (BGA) assembly allows designers to maximize component density without increasing the board size. From smartphones and IoT devices to medical and industrial electronics, this approach delivers higher pin counts in a smaller footprint. BGA technology replaces traditional pins with solder balls under the package, and placing BGAs on both sides of the PCB increases the usable area, letting engineers create more compact and complex designs...

Ford-Philco Radio, Model FT9, 6-Tube Auto-Radio Receiver Data Sheet

This Radio Service Data Sheet covers the Ford-Philco radio model FT9, 6-tube auto-radio receiver. A large list is included at the bottom of the page of similar documents from vintage receiver schematics, troubleshooting tips, and alignment procedures. They were originally published in magazines like Radio-Craft, Radio and Television News, Radio News, etc. I scan and post them for the benefit of hobbyists who restore and service vintage electronics...

How Are Shortwaves Propagated?

Prior to atmospheric sounding rockets and orbiting satellites, all information gained and theories developed on the nature of Earth's upper atmosphere and its interaction with electromagnetic waves were purely academic, not the result of empirical data. That is not to say the theories were wrong (although some were), just that they were incomplete. For that matter, even today there is still much to be learned and, according to an excellent article in the October 2015 issue of the ARRL's QST magazine titled "Five Myths of Propagation Dispelled," there is still a lot of misinformation being believed and promulgated about shortwaves and how they travel in the atmosphere. This work is a great testament to the level of expertise that exists in the realm of Amateur Radio, and the...

Tuesday the 17th

Easy-to-Build Beam Antenna

I wonder whether Mr. Jim Fahenstock, author of this 1960 Popular Electronics magazine article titled "Easy-to-Build Beam Antennas," was related to Archer Pleasant Fahnestock, president of the Fahnestock Electric Company, maker of the famous Fahnestock Clips? A Web search turns up plenty of Fahenstocks all over the country now (including some convicted criminals!), but how many could there have been in 1960. But I digress... This article highlights the growing necessity of beam antennas for amateur radio operators facing increasing spectrum congestion. By utilizing readily available hardware store aluminum, hobbyists can construct...

Blonde QRM

Ok, here's a little dose of Ham comedy for your Friday afternoon. It's a little bit kooky by today's standards, but in 1940 the style of humor it fits right in. This could easily have been the plot in an old TV show like The Honeymooners, or one of the radio situation comedy (sitcom) programs like The Life of Riley. QRM, by the way, is Ham lingo for man-made signal interference, as opposed to QRN, which is atmospheric or "natural" signal interference. Enjoy...

Supercharging Atomically Thin Semiconductors

"Atomically thin semiconductors such as tungsten disulfide (WS₂) are emerging as key materials for next-generation photonic technologies. Although they consist of just a single layer of atoms, they support tightly bound excitons, which are electron-hole pairs that interact strongly with light. These materials can also produce new colors of light through nonlinear optical effects such as second-harmonic generation. Because of these capabilities, they are considered promising for quantum optics, sensing, and compact on-chip light sources. However, their atomic-scale thickness also presents..."

Carl and Jerry: "The Hand of Selene"

This "The Hand of Selene" Carl and Jerry adventure appeared in the November 1960 issue of Popular Electronics just in time for Halloween. The magazine would have arrived in mailboxes on newsstands sometime in October. With the great popularity of zombies and the undead these days (in which I personally have zero interest), the scheme outlined here to make the hand of Selene (an Egyptian moon goddess) tap out answers to a soothsayer's questions would be a great scheme to use at a Halloween party. Read on to discover the tech savvy teenagers' clever implementation...

International Model 66 and 666, 6-Tube Superhet Radio Service Data Sheet

This "Radio Service Data Sheet" covers the International Kadette Model 66 and 666, superheterodyne receiver. Most - if not all - electronics servicemen had subscriptions to these magazines because they were a ready source of not just these service sheets, but because of the extensive articles offering advice on servicing radios and televisions. In fact, many electronics manufacturers had a policy of supplying service data only to bona fide shops. A large list is included at the bottom of the page of similar documents from vintage receiver schematics, troubleshooting tips, and alignment procedures. They were originally published in magazines like Radio-Craft (this April 1936 issue), Radio and Television News...

Monday the 16th

WWV - Free Government Test Signals

Compared to the 1960 era, when users relied on complex manual tuning, analog "whistles," and periodic signal cycles, modern WWV signals remain broadcast by the NIST but are now accessed by automated hardware and software-defined radios. This 1960 Popular Electronics magazine article serves as a technical guide for using NBS WWV radio transmissions as a precision tool for home laboratory calibration. By tuning a short-wave receiver to WWV's specific frequencies, hobbyists could perform direct or harmonic comparisons to calibrate signal...

How to Use Your Radio

This 1934 edition of Tower Radio magazine was thrown in with a batch of vintage radio magazines I bought on eBay. Most of the content pertains to entertainers of the day rather than with technical issues. Reportedly, it was only sold at Woolworth's stores. Ironically, the number of households with over-the-air radio listeners today, at least as a percentage of the population if not in absolute numbers, is probably about the same as in 1934 when commercial radio broadcasting was just getting a foothold. These days, a majority of people listen to radio and podcasts via cellphone and/or Internet streaming media than from over-the-air broadcasts, even while in their cars. Organizations like the National Association of Broadcasters are...

"Mouse Bite" Defects Inside Computer Chips

"Researchers at Cornell University have achieved something chipmakers have long wanted. Using advanced high-resolution 3D imaging, they have directly observed atomic-scale defects inside computer chips for the first time. These tiny flaws can interfere with performance and reliability in modern electronics. The new imaging approach was developed in collaboration with Taiwan Semiconductor Manufacturing Company (TSMC) and Advanced Semiconductor Materials (ASM). Because computer chips power everything from smartphones and cars to AI data centers and quantum computers..."

Mac's Radio Service Shop: Mac Quotes Benjamin Franklin

Well I'll be darned, old Mac the master radio repairman taught me something else new this month. Along with giving sidekick Barney a lesson on business ethics and how honest dealing can pay dividends as societal conditions change, he also put on his Sherlock Holmes cap and deduced a surprising cause for circuit failure based on the physical location of a lady's radio; read on to learn the details. As usual, the exact scenarios of the stories do not apply to today's environment and/or equipment, but the troubleshooting logic certainly does...

Make Extra Profits Changing Push-Button Radios

The old pushbutton radio tuners were an ingenuous bit of electromechanical wizardry. For those too young to have experienced them, operation was simple - turn the radio tuning knob to your broadcast station, pull out the lever/button, and then push it all the way back in. Done. The next time you pushed that button, the mechanism would slew the tuning dial to that position, taking the tuning elements (usually just a variable capacitor) with it. For most modern electronic radios, you program the station button by pushing and holding it for a few seconds until a beep is heard. My father never quite got the hang of tuning the pushbutton radio in his old Rambler (vacuum tubes) or even his 1972 Chevy pickup...

These archive pages are provided in order to make it easier for you to find items that you remember seeing on the RF Cafe homepage. Of course probably the easiest way to find anything on the website is to use the "Search RF Cafe" box at the top of every page. Some quoted items have been shortened to save space. About RF Cafe.

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