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What's Your EQ?

What's Your EQ?, April 1964 Radio-Electronics - RF CafeFinish up your week by considering these three "What's Your EQ" circuit challenges that appeared in a 1964 issue of Radio-Electronics magazine. They were submitted for consideration by readers, and sometimes by staff writers. The first is yet another form of the Black Box mystery component. Kendall Collins sort of gives away part of the answer in the problem statement. The second is a fairly straight-forward switching circuit. You'll get it with no problem. The third is most challenging. Don't be put off by the presence of a vacuum tube in the schematic. Mentally replace it with a FET and go from there. Interestingly, there is a lot of forum chatter about the Dynakit "Stereocator" feature regarding stereo reception...

GaN HEMT Hits 85.2% PAE at 2.45 GHz

GaN HEMT Hits 85.2% PAE at 2.45 GHz - RF Cafe"Japan-based Fujitsu Ltd has reported gallium nitride (GaN) high-electron-mobility transistors (HEMTs) on free-standing GaN substrates operating at 2.45 GHz in the industrial, scientific & medical (ISM, 2.4–2.5 GHz) reserved band with 85.2% power-added efficiency (PAE) and 89.0% drain efficiency (DE) [Toshihiro Ohki et al, Appl. Phys. Express, p18, p034004, 2025]. The team reports: 'To the best of our knowledge, our device sets a new record for the highest power-added efficiency and drain efficiency among discrete GaN HEMTs, highlighting the superior potential of GaN-on-GaN HEMTs for highly efficient RF power amplifiers..."

Our Electronic Future

Our Electronic Future, May 1967 Radio-Electronics - RF CafeIn his 1967 Radio-Electronics magazine column, editor Forest Belt envisioned the 1970s as a decade of radical electronic transformation, where homes would become "total-electronic" environments controlled by advanced technology - from computer-assisted cooking and video communicators to 3D television, laser communications, and even sleep-enhancing atmospheric systems. He urged electronics professionals, experimenters, and service technicians to prepare for this future, emphasizing that innovation and broad technical expertise would be critical to meeting consumer demands for ever-newer gadgets and conveniences. Belt warned that technicians who failed to adapt would be left behind, while those mastering emerging fields like fuel cells and heatless...

Negro Pilots Get Wings at Tuskegee Institute

Negro Pilots Get Wings at Tuskegee Institute, March 23, 1942 Life - RF CafeAt Tuskegee, Alabama, March 7, Colonel Frederick V. H. Kimble, U. S. A., pinned wings on the blouses of five young Negro lieutenants, members of the first graduating class of the Army's first Negro air school. Since last July they had undergone all the primary and advanced training to which white Army cadets at Randolph and Kelly fields are subject. Now they are charter members of the Air Force's 99th (all Negro) Pursuit Squadron, established last summer at a $2,000,000 airdrome near Alabama's famed Tuskegee Institute and now developing into one of the Army's biggest training bases...

Engineering & Tech Headlines <Archives>

• 3% 2025 Chip Capex Growth

• Drink Coffee Every Day to Reduce Cancer Risk

• Deutsche Telekom Quantum Internet Record

• Satellite-Hungry Orange Taps Telesat

• UK Invests £23M in Telecoms R&D

News Briefs

News Briefs, August 1968 Radio-Electronics - RF CafeIn August 1968, Radio-Electronics magazine's "News Briefs" reported on RCA's groundbreaking development of liquid crystal displays (LCDs), demonstrating how an electric field could turn transparent liquid crystals opaque - a key step toward flat-panel TVs. The article explained that these displays, just 0.001" thick and requiring minimal power, could be driven by integrated circuits and were visible even in bright light, unlike traditional CRTs. That "Radar Colander" photo looks like an out-of-this-world being - the lady's hairdo that is, not the metal hemisphere! Additionally, the Supreme Court ruled 7-0 that the FCC had authority to regulate CATV systems, reversing a lower court decision and impacting cable operations nationwide...

Meters for Beginners

Meters for Beginners, November 1964 Radio-Electronics - RF CafeThis 1964 Radio-Electronics magazine article details the operation of common electrical meters - voltmeters, milliammeters, and ohmmeters - all based on Ohm's law (I = E/R). The core component is the d'Arsonval movement, a DC-sensitive mechanism that can measure AC when paired with rectifiers. Voltmeters use multiplier resistors for different ranges, while ohmmeters employ an internal battery, producing a nonlinear scale. AC measurements rely on rectifiers to determine RMS voltage (0.707 of peak sine wave), though this method only works for pure sine waves. The article also explains practical circuits, including protection features like fuses, and discusses voltmeter sensitivity (ohms/volt), emphasizing that higher input resistance minimizes measurement errors by reducing circuit loading. Full-wave rectification improves sensitivity compared to half-wave setups...

Next-Gen Copper Alloy Pushes Past Limits

Next-Gen Copper Alloy Pushes Past Limits - RF Cafe"A team of researchers from Arizona State University, the U.S. Army Research Laboratory (ARL), Lehigh University, and Louisiana State University has developed a groundbreaking high-temperature copper alloy with outstanding thermal stability and mechanical strength. Their study, published in the journal Science, presents a novel bulk nanocrystalline alloy, Cu-3Ta-0.5Li, that demonstrates exceptional resistance to grain coarsening and creep deformation, even at temperatures approaching its melting point. 'Our alloy design approach mimics the strengthening mechanisms..."

What's Your EQ?

What's Your EQ?, February 1963 Radio-Electronics - RF CafeThree more problems await your attention here to challenge your Electronics Quotient (EQ), compliments of the February 1963 issue of Radio-Electronics magazine. First in line is figuring a way to determine which of five boxes of resistors contains mismarked components. It's a variation on a fairly common way to test components. The second is another Black Box; it's a bit simpler than usual. Hint: WWTD? (What would Thévénin do?). The third is a typical method of wiring a series of switches so that a device can be turned on or off from any number of locations. I recently implemented such a wiring job to control basement lights from four doorways - no big deal. Have fun...

Nation-Wide Television is Now in the Making

Nation-Wide Television is Now in the Making, January 1948, Radio-Craft - RF CafeDr. Allen Du Mont played a huge role in making television practical because of the improvements he made to the cathode ray tube (CRT). Prior to his work, the lifespan of a CRT was measured in tens of hours, and they were expensive, so their use was limited to special military and research applications. Du Mont's interest in "wireless" began at an early age, and he earned his commercial radio operator's license at the age of 14 (in 1915). He designed and produced oscillographs (i.e., oscilloscopes) that incorporated his CRTs. His involvement in the television industry was a natural evolution and extension of the work done in related industries. The DuMont Television Network was formed...

Thanks to PCB Directory for Continued Support!

PCB  Directory - RF CafeThe leading website for the PCB industry. PCB Directory is the largest directory of Printed Circuit Board (PCB) Manufacturers, Assembly houses, and Design Services on the Internet. We have listed the leading printed circuit board manufacturers around the world and made them searchable by their capabilities - Number of laminates used, Board thicknesses supported, Number of layers supported, Types of substrates (FR-4, Rogers, flexible, rigid), Geographical location (U.S., China), kinds of services (manufacturing, fabrication, assembly, prototype), and more. Fast turn-around on quotations for PCB fabrication and assembly.

Electronics-Themed Comics

Electronics-Themed Comics, August 1966 Radio-Electronics - RF CafeThese two electronics-themed comics appeared in a 1966 issue of Radio-Electronics magazine. The page 40 comic is especially funny, IMHO. The term that best fits this scenario is "anachronism," which is an object or concept that is out of its proper historical time period. You'll concur once you see the comic. In 1966, real-world lasers - as opposed to those found in science fiction - had output powers in the range of watts or tens of watts. Maybe a hundred watts from a CO2 laser in a laboratory setting like in the page 93 comic. Still, the concept of a laser powerful enough to be used as a weapon - capable of vaporizing an enemy - was reality in most people's minds...

DNA Circuits Come Alive

DNA Circuits Come Alive - RF Cafe"DNA strand displacement circuits are inching closer to becoming cellular machines. Scientists are finding ways to make these programmable nanodevices stable and functional inside living cells. If successful, they could revolutionize how we interface with and control biology at the molecular level. A recent review published in Intelligent Computing, titled 'From the Test Tube to the Cell: A Homecoming for DNA Computing Circuits?' outlines major advances in the effort to bring DNA computing circuits into living cells. The authors describe how dynamic nanodevices powered by DNA strand displacement reactions could soon perform..."

RF Millimeter Wave Body Scanners

everything RF Millimeter Wave Body Scanners - RF Cafeeverything RF is the Internet's largest source for mmWave scanners, with helpful search function for your specific needs. mm-Wave Security Scanners use high-frequency millimeter waves to create detailed 3D images of objects and identify objects concealed under layers of clothing. mmWaves can penetrate clothing but not the skin or other dense materials, making them ideal for detecting hidden objects without revealing detailed body contours, thus addressing privacy concerns. This makes them ideal as security scanners in Airports and other venues like stadiums, train stations and other high-traffic venues. mmWave security scanners from the leading manufacturers are listed here.

News Briefs

News Briefs, June 1963 Radio-Electronics - RF CafeA pair of items from this June 1963 Radio-Electronics magazine "News Briefs" column stands out: "Born 15 years ago this month were the transistor, June 30, and the long-playing record, June 21." Hard to imagine being there to reading that back in the day. Also noted was the world's first IEEE convention, held March 25-28 in New York City. Subjects presented 250 papers at 54 session. This online document discusses the IRE's award recipients to be honored at that March 1963 meeting. This doc is typical of the extremes corporations go to in order to specify and control their "brand," in this case the simple IEEE "kite" logo and text - sheesh! More TV sets were then in use abroad than in the U.S., reported Television Factbook. At the end of 1961, there were 54 million sets in foreign countries. By October, 1962, the total was 65 million, as compared to 60 million in the U.S. That, of course, is the sum of all countries other than the U.S.

Extra-Terrestrial Relays, by Arthur C. Clarke

Extra-Terrestrial Relays, by Arthur C. Clarke - RF CafeAsk and ye shall receive... at least sometimes. I posted a request for an article by science fiction writer Arthur C. Clarke, of 2001: A Space Odyssey fame, describing a geostationary satellite system that was published in the October 1945 edition of Wireless World magazine. Thanks to RF Cafe visitor Terry W., from the great state of Oklahoma, it is now available for everyone to enjoy. Clarke was not just a sci-fi writer, but also an educated visionary and card-carrying member of the British Interplanetary Society, who proposed many technological solutions to issues of his day. In this instance, the challenge was developing an efficient means to distribute TV signals across Europe and the world. Clarke's calculations for the necessary number of repeater towers proved that concept impractical, so he proposed using modified surplus German V2 rockets to launch Earth-orbiting "artificial satellites," powered...

Thanks Once Again to everythingRF for Long-Time Support!

everything RF Searchable Database - RF CafePlease take a few moments to visit the everythingRF website to see how they can assist you with your project. everythingRF is a product discovery platform for RF and microwave products and services. They currently have 333,423 products from more than 2198 companies across 460 categories in their database and enable engineers to search for them using their customized parametric search tool. Amplifiers, test equipment, power couplers and dividers, coaxial connectors, waveguide, antennas, filters, mixers, power supplies, and everything else. Please visit everythingRF today to see how they can help you.

What's Your EQ?

What's Your EQ?, August 1966 Radio-Electronics - RF CafeHere are two more circuit problems for you from the August 1966 issue of Radio-Electronics magazine. The first is a fairly familiar tapered resistance network where you are asked to determine the input resistance of the infinite network. Out of curiosity, I asked Arya, ChatGPT 4.1, Grok 3, and Gemini 2.5 Pro, to calculate the given formula to 75 decimal places. I received four different answers. All agreed to 33 decimal places, and three of them agreed to 51 places, then everything fell apart. Once again I warn: Do not blindly trust the results of AI clients. Verify everything important!!! The other problem is to determine the output waveform of a duo-diode vacuum tube circuit. The semiconductor equivalent is a pair of PN junction diodes with the anodes at the top.

Engineering AI Jobs in 2025

Engineering AI Jobs in 2025 - RF Cafe"It seems AI jobs are here to stay, based on the latest data from the 2025 AI Index Report. To better understand the current state of AI, the annual report from Stanford University's Institute for Human-Centered Artificial Intelligence (HAI) collects a wide range of information on model performance, investment, public opinion, and more. Every year, Spectrum summarizes our top takeaways from the entire report by plucking out a series of charts, but here we zero in on the technology's effect on the workforce. Much of the report’s findings about jobs..."

Inventors of Radio: Boris Rosing

Inventors of Radio: Boris Rosing, April 1966 Radio-Electronics - RF CafeIn the mid 1960s, Radio-Craft magazine ran a series of articles on "Inventors of Radio." This April 1966 issue featured Boris Lvovitch Rosing (1869–1933), a Russia-born physicist and pioneer of television technology. Rosing was born in St. Petersburg, where he studied under Heinrich Friedrich Emil Lenz and later taught at the Technological Institute. Beginning in 1902, he experimented with cathode-ray tubes for image transmission, developing the first electronic television device by 1907, which used rotating drums and a modulated electron beam to produce images. His breakthrough came in 1911 when he successfully displayed simple images, earning him recognition and awards. Despite interruptions from World War I and the Russian Revolution, Rosing continued refining his designs, achieving higher-resolution scans...

Multicolor Radar

Multicolor Radar, June 1955 Popular Electronics - RF CafeWhat's the big deal about multicolor radar, you might ask? Not much today, but in 1955 color displays were in their infancy. The earliest color cathode ray tubes (CRTs), developed by John Logie Baird in the early 1940s, used just two phosphor colors (magenta and cyan), illuminated by two separate electron guns, to produce a limited color display. Ernest Lawrence came along later in the decade with his tri-color Chromatron CRT, which had separate red, blue and green phosphor dots deposited in a triangular pattern across the inner face of the tube. That is the scheme employed in this first multicolor radar system. It was a major improvement for air traffic controllers since it facilitated...

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. Take a good look at the people in these photos, and remember they are the ones who laid the foundations for the modern world we take for granted. Such sacrifice has built the modern world...

LEO Networks Push Geostationary Giants to Innovate

Low Earth Orbit Networks Pushing Geostationary Giants to Innovate - RF Cafe"For decades, Geostationary Earth Orbit (GEO) operators were in the communications catbird's seat 22,000 miles above the Earth, but the arrival of Low Earth Orbit (LEO) networks, like Elon Musk's Starlink, is bringing the Old Guard in satellite com down to terra firma. 'The proprietary and specialized GEO infrastructure of the past is now weighing down space industry incumbents that find themselves needing to rapidly innovate against mounting competition,' ABI Research Senior Analyst Andrew Cavalier wrote in a recent research report. An indicator that innovation..."

What's Your EQ?

What's Your EQ?, February 1966 Radio-Electronics - RF CafeIf it seems like I've been posting a lot of these "What's Your EQ?" features, there's a good reason... I have been posting a lot of them lately. I had created the pages long ago, and somehow I forgot to go back and complete them with the drawings. Expect to see a dozen or so more in fairly short order. The circuit challenges are usually submitted by Radio-Electronics magazine's readers, but occasionally one of the columnists will contribute. "How Wide?" seems like you would need the value of L to calculate, but given that the problem is presented without it, there must be a way, right? With the Series-Parallel circuit, I got as far...

New: Espresso Engineering Workbook v4.20.2025

Espresso Engineering Workbook v4.20.2025 - RF CafeRF Cafe's spreadsheet-based engineering and science calculator - Espresso Engineering Workbook™ (click to download) - is a collection of surface area and volume calculators for many geometric solids. RF Cafe Espresso Engineering Workbook™ is provided at no cost, compliments of my generous sponsors. The newest additions are calculators for Opamps, FM Sidebands, and FM Modulation. That makes 41 worksheets containing hundreds of calculation. There are many online calculators for these and other functions, but sometimes having a convenient desktop version makes life easier. While developing Espresso Engineering Workbook, I conduct extensive research and testing to help assure the correct equations are used and accurate results are displayed. Download your copy today, and pass the word onto a friend...

QST: I.O.U. News

I.O.U. News, April 1933 QST - RF CafeI have noted in the past how humor in the days of yore was somewhat, shall we say, different, than what it is today. My vintage aviation, mechanics, and electronics magazine from the early to middle part of the last century contained comics and humor pieces that in a lot of cases were not very funny because of a lack of cleverness, and in some cases were downright stupid. A search of both RFCafe.com and AirplanesAndRockets.com will bear out my assertion. Look at the stuff from before 1950. This 1933 QST magazine, flagship publication of the American Radio Relay League (ARRL), is a good example. It was the April edition, which means it was chock full of puns, comics, gags, and faux articles and news bits. Some of them are pretty good, but you might need to adopt an alternate frame of mind to "get" them...

Thanks Again to LadyBug for Continued Support!

LadyBug Technologies RF Power Sensors - RF CafeLadyBug Technologies was founded in 2004 by two microwave engineers with a passion for quality microwave test instrumentation. Our employees offer many years experience in the design and manufacture of the worlds best vector network analyzers, spectrum analyzers, power meters and associated components. The management team has additional experience in optical power testing, military radar and a variety of programming environments including LabVIEW, VEE and other languages often used in programmatic systems. Extensive experience in a broad spectrum of demanding measurement applications. You can be assured that our Power Sensors are designed, built, tested and calibrated without compromise.

Electronics-Themed Comics

Electronics-Themed Comics, October 1964 Radio-Electronics - RF CafeIt's Friday afternoon as I prepare this trio of vintage electronics-themed comics for posting. They all appeared in the October 1964 issue of Radio-Electronics magazine. All three reflect the home entertainment craze of the era, in particular TV. Color TV was making inroads into homes, despite the relatively high cost, and in 1964, many programs were still being broadcast in black and white (B&W). Stereo systems were huge as well, and you will find many comics depicting stereo themes in the large list at the bottom of the page. The love-hate relationship the public had with electronics equipment repairmen (it worked both ways) is evident here. Millennials will never be able to relate to the slings and arrows suffered by those of us who lived during the CRT TV times, but then we Boomers...

Today in Science History

Today in Science History - RF Cafe

Quiz #40: Introduction to Antenna Analysis Using EM Simulation

RF Cafe Quiz #40: Introduction to Antenna Analysis Using EM SimulationThis quiz is based on the information presented in Introduction to Antenna Analysis Using EM Simulation, by Hiroaki Kogure, Yoshie Kogure, and James C. Rautio, published by Artech House. It is written for novice engineers and engineering students. This easy-to-comprehend resource offers readers thorough introductory-level treatment of antenna analysis using electromagnetic (EM) simulators. This richly-illustrated book shows how to use EM software to analyze and tune wireless antennas to meet specific requirements. Readers learn important wireless antenna design terminology and gain a detailed understanding of how antennas work. Moreover, the book offers guidance in troubleshooting problems with wireless antenna designs...

Meet Mr. FET ... the Transistor That Thinks It's a Tube

Meet Mr. FET ... the Transistor That Thinks It's a Tube, February 1967 Popular Electronics - RF CafeYesterday was the 71st anniversary of the announcement of the transistor's invention by Drs. Shockley, Bardeen, and Brattain at Bell Labs, but it was a Sunday so not as many RF Cafe visitors saw the commemorative title graphic I used. Their transistor was a current-controlled signal amplifying device as opposed to the field-effect transistor (FET) which is a voltage-controlled signal amplifying device - as is the vacuum tube. I never thought about it before, but maybe that had something to do with the electronics world's hesitancy to adopt the transistor as a replacement for the tube. Early in the transistor's history, practical applications were limited due to low reliability, low power handling, low frequency, lack of ruggedness in harsh operating conditions, and other shortcomings compared to established and much refined vacuum tubes was reason enough to shun the newfangled technology, but that current-controlled thing...

Short Waves of Tomorrow

Short Waves of Tomorrow, January 1938 Radio-Craft - RF CafeHugo Gernsback, in a 1938 issue of his Radio-Craft magazine, lampooned his contemporaries who boldly declared that by then (1938) there was nothing left to be invented regarding radio equipment for shortwave communications. Wisely citing the well-known instance of a patent examiner who quit his post in 1870 because, as the man put it, all useful things had been invented and there was nothing meaningful left to patent, Mr. Gernsback challenged his readers to keep this article for 25 years and then go back and read it while being aware of all the new and wonderful short wave devices that had been invented since 1938. It has now been more than 80 hence since the challenge was issued, and not only has the state of the art of short waves advanced beyond any of their wildest dreams, but entire new realms of radio and optical communications have been born and evolved that only futurist like Hugo Gernsback, H.G. Wells, Jules Verne, and Edgar Allen Poe (Poe was considered a great sci-fi writer) could ever have even imagined.

RF Cafe Engineering Puzzle for December 30

RF Cafe EngineeringEach 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 Lamarr or the Bikini Atoll, respectively. Enjoy...

Mac's Service Shop: Keeping Abreast of Your Field

Mac's Service Shop: Keeping Abreast of Your Field, April 1969 Electronics World - RF CafeMac and Barney discuss with some degree of trepidation the alarmingly increasing rate at which new electronics technology is being developed and marketed. As service shop owner and technician, respectively, they needed to constantly educate themselves on new components and circuits in order to stay current and be efficient enough to turn a profit. Mac recounts his lengthy background beginning with the days of mainly battery-powered AM radios, and progressing through AC-DC, FM and all-band (shortwave) radio, B&W television and the color TV, CB radios, and a new breed of appliances with electronic controls...

RF & Electronics Symbols for Office™

RF & Electronics Schematic & Block Diagram Symbols for Office™ r2 - RF CafeIt was a lot of work, but I finally finished a version of the "RF & Electronics Schematic & Block Diagram Symbols"" that works well with Microsoft Office™ programs Word™, Excel™, and Power Point™. This is an equivalent of the extensive set of amplifier, mixer, filter, switch, connector, waveguide, digital, analog, antenna, and other commonly used symbols for system block diagrams and schematics created for Visio™. Each of the 1,000+ symbols was exported individually from Visio in the EMF file format, then imported into Word on a Drawing Canvas. The EMF format allows an image to be scaled up or down without becoming pixelated, so all the shapes can be resized in a document and still look good. The imported symbols can also be UnGrouped into their original constituent parts for editing...

Low Plate-Potential Tubes

Low Plate-Potential Tubes, January 1957 Radio & Television News - RF CafeOnce radios in the family car became a standard accessory, a push ensued to make them cheaper, more reliable, and service-free. A major Achilles' Heel was the high voltage power supply required to energize vacuum tubes. Known as vibrator power supplies due to using an oscillator to convert the battery's 12 DC supply (some autos still used 6 V systems) into AC that could be transformed up to the 300 volts used by most tubes of the day, most early failures were attributed to the circuits. They also caused annoying noise in the audio output if careful filtering and installation was not performed. Having been invented only a couple years earlier, transistors were being designed into the power supplies, but low-voltage tubes were still needed for the electronics. In response to the demand, low-voltage tubes...

Math Logic Puzzles from the 1961 Old Farmer's Almanac

Math Logic Puzzles from the 1961 Old Farmer's Almanac (Kirt's Cogitation #304) - RF CafeFarmers must be a lot smarter than we tend to give them credit for being. These math and logic puzzles that appeared in the 1961 Old Farmer's Almanac are not a duffer's task to complete. Be careful to consider units of measure based on the venues. Puzzle I is a relatively simple trigonometry problem, although the wording of the problem statement is very confusing; it took some head scratching to figure out what was meant. Puzzle III required me to opt for a graphical solution since I could not come up with enough independent equations for the number of unknowns. If you look at the OFA page scan...

Destiny and Geomagnetism

Destiny and Geomagnetism, July 1971 Popular Electronics - RF CafeIf you read the physics and geographic news of the day, most likely you have seen articles on the rapidly increasing migration rate of the geomagnetic "north pole" over the past few decades. Magnetic north has never exactly lined up with geometric north (as borne out in geological samples of rocks), and neither has it ever been uniformly distributed across the globe. Ancient explorers on terra firma and at sea knew that a magnetic compass needle did not align with the same stars, moon, or sun position for every location, after accounting for difference in longitude. That is because the earth's magnetic field is very nonuniform in strength and does not follow straight lines from pole to pole as they more generally do from outer space. A correction factor must be applied to any magnetic north indication based ...

Satellite Electronics

Satellite Electronics, March 1958 Radio Electronics - RF CafeEcho 1 was put into orbit on August 12, 1960. This article was written 2½ years earlier in 1958 by Radio-Electronics editor Hugo Gernsback. A technology visionary and prolific inventor and writer, Mr. Gernsback astutely outlined the vast number of advantages that had already been and would in the future be afforded the science community by virtue of a satellite's perspective from space. Two of the Soviet Union's Sputnik satellites had revealed the surprisingly irregular shape and gravitational influence of the Earth, information about the upper atmosphere, and aspects of space environment effects on radio communications. America was scrambling to catch up. Gernsback and others postulated the configuration of active relay transceivers powered by solar cells and storage batteries, satellite-based television and radio...

Room Acoustics for Stereo and Entertainment Systems

Room Acoustics for Stereo and Entertainment Systems, February 1960 Electronics World - RF CafeHome entertainment is as big of a deal (or bigger) today as it was in the 1960's and 1970's when high fidelity personal sound gear was coming into the mainstream. Capability and features were going up while the price was coming down on really nice equipment. In order to achieve theater quality sound from your stereo and/or large screen television, thought and planning is essential or you will end up with a confusing mess of directed and reflected sounds. This article contains very valuable information on room configuration and sound absorbing materials and strategies. A fairly extensive table of common floor, wall, and ceiling sound absorption coefficients is provided, as are charts of reverberation times of various venues and volumes...

Reverse Current Keeps Ferry Afloat

Reverse Current Keeps Ferry Afloat, December 1965 Popular Electronics - RF CafeA news story with a title about a boat and reverse current is more likely to be referring to water flow in a river or stream than about electrical current in a conductor. Having grown up in a neighborhood next to a tributary of the Chesapeake Bay, I spent quite a bit of time around boats, both large and small. Salt water is particularly destructive to metal hulls due to cathodic corrosion, exacerbated by the salt water's conductivity. While working as an electrician in the 1970s, I installed electrical supplies for a few dockside cathodic protection system that probably functioned like the one described in this 1965 issue of Popular Electronics magazine. The principle is fairly simple whereby anodes are placed in the water around the hull and a counter-current is induced...

Microwaves Part V - Waveguide

Microwaves Part V - Waveguide, September 1949 Radio-Electronics - RF CafeAlthough the subtitle of Part V of the 1949 Radio-Electronics magazine "Microwaves" introductory series in refers to Special Sections of Waveguide Are Employed as Transformers, author Palmer is discussing not impedance transformers but physical configuration transformations. That includes in-between rectangular, circular, and oval cross-sections, in-between waveguide and coaxial cable, and rotary joints. Signal injection and extraction via stubs are also covered. He provides a high level introductory description of how microwave frequency waveguide works without delving into the scary mathematics required to design the components...

Applications of Small High-Voltage Selenium Rectifiers

Applications of Small High-Voltage Selenium Rectifiers, October 1956 Radio & Television News - RF CafeSelenium rectifiers were the first widely used as other-than-vacuum-tube circuit elements for various power supply designs. They were not very practical as detectors in receiver circuits unless signal levels were high. Properly manufactured selenium rectifiers were much more rugged and reliable than the tube equivalents, but generally were more expensive. Since the power supply is such a critical part of any electronic assembly, the tradeoff could be justified if only for the boost in a product's reputation for having fewer breakdown issues. While it is true that there are not many applications anymore for selenium rectifiers, vintage materials and methods sometime experience a reincarnation in some other form using modern formulations and manufacturing techniques. Having knowledge of previous work can help spawn ideas for research and development toward solving new problems...

Mac's Service Shop: Motorola's 1974 Color TV Receivers

Mac's Service Shop: Motorola's 1974 Color TV Receivers, November 1973 Popular Electronics - RF CafeEven if you are not, never were, and don't plan to be a color television serviceman, this installment of Mac's Service Shop that appeared in a 1973 issue of Popular Electronics provides an interesting insight into the manner in which the electronics industry was rapidly changing in the 1970s. By 1973 most manufacturers had fully committed to all solid state circuitry (except for the CRT, of course), and the competition was focusing on customer satisfaction. Point-to-point wiring of chassis with leaded resistors, capacitors, inductors, and interconnecting wires and coaxial cable gave way to multiple printed circuit boards (PCBs) with a maze of interconnecting wire harnesses. In theory the scheme was much more reliable and serviceable, and for the most part it was. The problem was that a lot of service guys were still struggling to come up to speed on the newfangled technology. Trying to use a 500 watt soldering iron...

Understanding Transistor Circuits

Understanding Transistor Circuits, August 1959 Popular Electronics - RF CafeIt had been only a little over a decade since the transistor was invented when this article appeared in the August 1959 edition of Popular Electronics. Transistors were still a mystery to most people, including engineers, technicians, and hobbyists. Author James Butterfield takes a unique approach in presenting the material by writing it as a dialog between an instructor and a student. If you are also new to transistors, this will be worth your while to read. The basics will never change. As an aside (and mentioned in the article), while still a technician I had a manager one time who actually told an engineer working for him that a transistor could be made by soldering two diodes together and using the center node as the base connection...

The Longitude Problem

Longitude: The True Story of a Lone Genius Who Solved the Greatest Scientific Problem of His Time - RF CafeKnowing 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...

Electronic Switching Quiz

Electronic Switching Quiz, October 1967 Popular Electronics - RF CafeI found one more electronics quiz in a copy of my vintage Popular Electronics magazine collection. Robert P. Balin published scores of these quizzes over the span of a couple decades. Unless you have created a few quizzes yourself, it might seem like there is nothing to it, but even relatively simple ones like this requires the creator to think up the problems and then guarantee that the answers given are correct. No, it's not rocket science, but try creating a dozen quizzes with 8 to 10 questions; it could take a while. Anywho[sic], this Electronic Switching Quiz requires you to consider the switch positions and then determine which lamps will turn on...

Television in Space

Television in Space, August 1965 Electronics World - RF CafeA mere five years elapsed from the time Echo, a gas-filled metallized plastic sphere that passively reflected radio signals back to Earth, was launched and the time that 35 television cameras had been launched into space. The Space Race was at a fever pitch. Although the Ruskies beat us in being the first to launch both an active satellite (Sputnik) and a man (Yuri Gagarin) into space, America's deep pool of intellectual resources, consisting of both native scientists and many of the world's top scientists who chose to flourish in freedom here rather than oppression behind the Iron Curtain, fostered the advantage that in short order established the U.S. as the leading super power both in space and on terra firma. TIROS satellites began providing real-time visual data on the Earth's weather in 1960. Not only were cameras transmitting images of the Earth, but a month before this issue of Electronics World went to press the Mariner spacecraft sent close-up images of the planet Mercury's surface...

Have You Seen Him?

Have You Seen Him?, April 1935 Short Wave Craft - RF CafeToday we have missing persons notices printed on milk cartons and computer-aged pictures of missing kids on bulletin boards at Walmart, and of course the Internet with all its various forms of publicity. In 1935, evidently, an electronics magazine was a proper venue for placing a missing person ad. At the time there was no convenient and accessible way for family members to reach out to a nationwide audience other than to place ads in magazines and/or newspapers in remote locations. I thought it odd to see such a placement in this edition of Short Wave Craft magazine, but considering the aforementioned, doing so is entirely reasonable for a worried family. I wonder how much it cost to place the notice? It's heartbreaking, really...

Homepage Archives for December 2022

Homepage Archives for December - RF CafeHomepage Archives for December 2022. Items on the RF Cafe homepage come and go at a pretty fast rate. In order to facilitate fast page loading, I keep the size reasonable - under a megabyte (ebay, Amazon, NY Times, etc., are multiple megabytes). New items are added at the top of the content area, and within a few days they shift off the bottom. If you recall seeing something on the homepage but now it is gone, fret not because many years I have maintained Homepage Archives.

LadyBug LB5954L Power Sensor with LAN Option - RF Cafe
RF Cascade Workbook 2018 by RF Cafe

withwave microwave devices - RF Cafe

Innovative Power Products Cool Chip Thermal Dissipation - RF Cafe