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New & Timely

New & Timely, December 1969 Radio-Electronics - RF CafeThe December 1969 issue of Radio-Electronics magazine's "New & Timely" column reported that at the National Electronic Association conference, technicians reported burns and eye damage caused by X-radiation from color TV sets under repair. Night vision scopes for commercial use were introduced by Raytheon, suitable for law enforcement, industrial security, and nature study. A joint U.S.-Indian plan planned to beam TV directly to millions of Indian villagers via a stationary applications satellite in 1972. The French Atomic Energy Commission used a superpowerful laser to create minute thermonuclear explosions, fusing deuterium...

Anatech Intros 3 New Filter Models for April 

Anatech Electronics Intros 3 New Filter Models for April 2025 - RF CafeAnatech Electronics offers the industry's largest portfolio of high-performance standard and customized RF and microwave filters and filter-related products for military, commercial, aerospace and defense, and industrial applications up to 40 GHz. Three new filter models have been added to the product line in April, including a 5500 MHz WiFi cavity bandpass filter, a 3437-3537 MHz ceramic duplexer filter, and a 1425 MHz cavity bandpass filter. Custom RF power filter and directional couplers designs can be designed and produced with required connector types when a standard cannot be found, or the requirements are such that a custom approach is necessary...

The Electron Microscope

The Electron Microscope, May 1955 Popular Electronics - RF CafeThis article published in a 1955 issue of Popular Electronics magazine is a really good primer on the history and working principles of the electron microscope. It also explains why such a device is needed; i.e., why an optical microscope cannot do the job when really high levels of magnification are required. As object dimensions are spaced at distances near to or less than the optical wavelength being observed, it becomes impossible to resolve into separate features. Accordingly, when observing at the upper end of the visible light spectrum at around 400 nm, under ideal conditions you would not be able to clearly discern two feature less than about 800 nm apart. Current (2019) CMOS gate thicknesses run about 5 μm, so visible light cannot be used to image those structures. Another resolution limiting factor is aperture size, which, depending on the wavelength causes diffraction patterns of two objects to overlap...

Pacific T.V. Vacuum Tube Supply

Pacific T.V. Vacuum Tube Supply - RF CafeIf you are a seasoned vintage electronics equipment aficionado, restorer, hobbyist, etc., then you most likely already have your own list of supply sources for vacuum tubes. Contrary to what others might think, there is still a healthy stock of tubes available from private websites like Pacific T.V. (hat tip to Bob Davis), as well as collective sites like eBay, Facebook Marketplace, Craigslist, and vintage electronic equipment forums. Prices for common tubes are surprisingly low if you shop around. If you need an output power amplifier for a commercial radio station, be prepared to shell out major wampum, though. Many NOS (new old stock) varieties in original boxes can be had, as well as used tubes. Most have been tested for specification compliance.

Westinghouse Wartime Products

Westinghouse Wartime Products, May 1943 Popular Mechanics - RF CafeWestinghouse is yet another bulwark company of America's foundational industrial age, beginning in the late 19th Century. George Westinghouse founded eponymously-named company, Westinghouse Electric & Manufacturing Company, in 1886, during the time he was working with Nikola Tesla (I wonder whether any of the current-day anti-Tesla nimrods are stupid enough to vandalize NT statues and monuments?) to institute a commercial electrification infrastructure. Mr. Westinghouse began his life of fame and fortune with a locomotive air brake design. During World War II, Westinghouse's many locations designed and manufactured many types of products to facilitate troops in all Theaters of Operation. This 1943 issue of Popular Mechanics magazine carried a full-page...

What's Your EQ?

What's Your EQ?, January 1963 Radio-Electronics - RF CafeThis set of three circuit analysis challenges appeared in the January 1963 issue of Radio-Electronics magazine. Readers, staff, and even come companies submitted the "What's Your EQ?" (EQ = Electronics Quotient) content. As an example of the latter, Cleveland Institute of Electronics provided "Draw the Waveform." Don't let the diode vacuum tube deter you from the puzzle. Just mentally replace the tube with a solid state diode symbol with the anode at the top where the tube's plate (anode) is shown. The negative element of a tube is called the cathode, same as the solid state diode. "Capacitor Charge" is easy enough. "Another 2-Box Light"...

2025 UK Engineering Salary Survey

2025 UK Engineering Salary Survey - RF Cafe"Despite increasingly intense competition for skills across all sectors of industry and a growing appetite amongst engineers for a new challenge, engineering salaries appear to have stagnated over the past 12 months. This is just one of the key findings of The Engineer's tenth annual salary survey, which is published in full on The Engineer's website in a new interactive digital format. Attracting responses from 621 engineers working across 12 different sectors, this year's survey was carried out between December 2024 and January 2025. As ever, the results provide a fascinating insight into UK engineering salaries and how engineers are feeling about their careers..."

Television and Sound

Television and Sound, January 1963 Radio-Electronics - RF CafeIn this 1963 issue of Radio-Electronics magazine, editor Hugo Gernsback reflects on the early days of television, noting that the first regular daily TV broadcast began on August 13, 1928, over radio stations WRNY and W2XAL, which were associated with his former publication, Radio News. Initially, these broadcasts were silent, featuring only moving images the size of a postage stamp, and it wasn't until 1931 that TV broadcasts included sound. Gernsback critiques the slow progress in improving the audio quality of television receivers, pointing out that despite advancements in high-fidelity and stereo audio technology, most TV sets still lacked these features due to regulatory restrictions by the FCC. He expresses hope that recent petitions to the FCC...

Exodus AMP20081, 80-1000 MHz, 500 W SSHPA

Exodus AMP20081, 80-1000 MHz, 500 W SSHPA - RF CafeExodus Advanced Communications, is a multinational RF communication equipment and engineering service company serving both commercial and government entities and their affiliates worldwide. Exodus' model AMP20081 high power solid state power amplifier (SSHPA) is ideal for broadband EMI-Lab, communications, and EW applications. Class A/AB linear design accommodates all modulations & industry standards. It covers 80-1000 MHz, producing 600 W nominal, with a 500 W P1dB and 56 dB minimum gain. Excellent flatness, optional monitoring parameters for forward/reflected power, VSWR, voltage, current & temperature sensing for superb reliability and ruggedness...

Electronics-Themed Comics

Electronics-Themed October 1944 & May 1945 Radio-Craft - RF CafeIn that these comics from Radio-Craft magazine have an electronics theme, you can claim looking at them is work-related. The themes of the comics reflect common scenarios of the 1944-1945 era in which they were published, but with not much modification can be applied to today's environment. People will always expect more features from products, will be critical of everything presented to them, and will want to haggle for the best deal from the used camel salesman. You might consider using one of them for your next conference or project status presentation. There is a list of many more similar comics at the bottom...

World's 1st Quantum Entanglement Communications Service

World's First Quantum Entanglement Communications Service Offered by QentComm - RF CafeIn a groundbreaking announcement that will forever transform global communications, QentComm®©™ (Quantum Entanglement Communications) has unveiled the world's first commercially viable quantum entanglement communication system. Dubbed QeG®©™ (Quantum entanglement Generation, pronounced kwee-gee), supplementing the traditional 4G, 5G, and 6G nomenclature, this revolutionary technology eliminates the limitations of traditional radio-based systems, delivering instantaneous, unlimited connectivity across any distance without reliance on satellites, cell towers, or fiber optics. Under the leadership of Kirt Blattenberger, QentComm (pronounced kwent-kahm) has created a system that defies conventional physics by utilizing quantum entanglement for real-time, secure communication between devices anywhere in the universe - including here on Earth...

Carl & Jerry: Secret of Round Island

Carl & Jerry: Secret of Round Island, March 1957 Popular Electronics - RF CafeIn this "Carl & Jerry" technodrama from a 1957 issue of Popular Electronics magazine, the two boys start out enjoy a casual day of kite flying, using a homebrew radio-controlled camera attached to the kite to capture an aerial view of Round Island in a lake. After successfully taking a picture, they develop the film and discover two men and an odd setup on the island. Curious, they return the next day, find a hidden tunnel, and stumble upon an illegal liquor still. As you might expect, the teens run into a heap of trouble when the moonshiners nab them. Using their combined ingenuity and knowledge of communications methods common to Ham radio operators of the era, contact was made and help was on the way. Read about Carl and Jerry's exploit and exactly what it was that saved the day - and their hides!

Ham Radio Students at DSES Radio Telescope

Amateur Radio Students Visit DSES Radio Telescope - RF Cafe"In late January 2025, 17 students and staff members from Las Animas High School (LAHS) in Colorado visited the Deep Space Exploration Society Radio Telescope (DSES) located at the Plishner Radio Astronomy and Space Sciences Center near Haswell, Colorado. They also got an introduction to amateur radio. 'This first field trip visit of high school students reflected the dreams of Michael Lowe, former DSES board president, who sought to create a center for radio astronomy and space science education in southeast Colorado,' said DSES President Myron Babcock, KL7YY..."

Old World Standards Breaking Through

Old World Standards Breaking Through, April 1966 Popular Electronics - RF CafeMaking format changes to magazines after many years of an established standard always ruffles the figurative feathers of a significant portion of regular readers. Two magazines I read monthly, Model Aviation and QST, recently underwent a format change - both of which I considered very nice. However, reader comments in the aftermath showed a few who were not impressed. Popular Electronics magazine in 1966 made announcements regarding plans to adopt some of the newer base units for physical measurements, including this one for beginning to use "Hertz" (Hz), along various numerical prefix forms, instead of "cycles per second" (cps). The editors give sound reason...

Harold Beverage of the Eponymously Named Antenna Type

Harold Beverage of Eponymously Named Antenna Type, August 1944, Radio-Craft - RF CafeThe Beverage Antenna, very familiar to amateur radio operators, is a simple but efficient, highly directional, non-resonant antenna that consists of a single straight wire of one or more wavelengths that is suspended above the ground. It is orientated parallel to the direction of intended reception. One end is terminated to ground through a resistor, and the other is connected to the receiver. The following quote comes from the patent (US1,81,089) text: "In accordance with theoretical considerations, if an antenna were to be freely suspended and if the surface of the earth constituted a perfectly conducting parallel plane, current waves would travel through...

Dear Mr. Fips: 30-Day Record Response

Dear Mr. Fips: 30-Day Record Response, June 1961 Radio-Electronics - RF CafeThis letter was sent to Hugo Gernsback, publisher of Radio-Electronics magazine, in response to the "30-Day Record Response" article penned by noted scientist and inventor Mohammed Ulysses Fips. In it, Stephen A. Kallis, Jr. heaped laud upon the "Most Revered and Esteemed Fips" for his long-term recording device (remember, 1961 was many decades before microminiature terabyte memory and microprocessors) were available, and chastises Mr. Gernsback for evidently calling into question the authenticity of the recorder. Kallis, a self-proclaimed stereo enthusiast, bolsters Fips' case by citing "A Proposed Listening Area," by the Institute of Synergistic Statics Proceedings...

Ulano Masking Films - Rubylith

Ulano Masking Films, December 27, 1965 Electronics Magazine - RF CafeRaise your hand if you're old enough to remember doing printed circuit board layout using Rubylith tape. My hand is up. Back in the early 1980s, I did prototype PCB designs in an engineering development lab at Westinghouse Electric's Oceanic Division. Most of it was for analog and RF substrates that would be photographically reduced in size for use with bare integrated circuit die and surface mount passive components (Rs, Ls, and Cs), upon which I would later epoxy-mount those components and wire-bond everything using 1-mil gold wire. However, there were projects where full-size leaded components were used on a through-hole PCB that used not only the Rubylith tapes but also sheets with special electronics shapes for solder pads around the holes for components leads, ground and power planes, board-edge connectors...

Mind-Bending Quantum Phase Flip

Mind-Bending Quantum Phase Flip - RF Cafe"Quantum systems don't just transition between phases - they do so in ways that defy classical intuition. A new experiment has directly observed these dissipative phase transitions (DPTs), revealing how quantum states shift under carefully controlled conditions. This breakthrough could unlock powerful new techniques for stabilizing quantum computers and sensors, making them more resilient and precise than ever before. A new frontier phase transitions, like water freezing into ice, are a familiar part of everyday life. In quantum systems, however, these transitions can be far more extreme, governed by principles like Heisenberg's uncertainty..."

DX Hams Do Get Around

DX Hams Do Get Around (November 1940 Boys' Life Article) - Airplanes and RocketsIn this November 1940 issue of the Boy Scouts Boys' Life magazine, amateur radio operators, or "hams," are described as having the ability to communicate across vast distances, connecting far-flung locations such as Goulds, Florida, Cali, Colombia, Cairo, Kenilworth, England, Bombay, and Brisbane. These operators, licensed by the Federal Communications Commission, engage in various activities such as talking to distant stations, participating in contests, and providing emergency communication during natural disasters. With call letters assigned by international treaty, these stations use a combination of code and phone to make contact, exchanging reports and QSL cards. The Radio merit badge was first offered in 1918 and has been...

Thanks Again to ConductRF for Continued Support!

ConductRF coaxial cables & connectors - RF CafeConductRF is continually innovating and developing new and improved solutions for RF Interconnect needs. See the latest TESTeCON RF Test Cables for labs. ConductRF makes production and test coax cable assemblies for amplitude and phased matched VNA applications as well as standard & precision RF connectors. Over 1,000 solutions for low PIM in-building to choose from in the iBwave component library. They also provide custom coax solutions for applications where some standard just won't do. A partnership with Newark assures fast, reliable access. Please visit ConductRF today to see how they can help your project! 

Electronic Razor

Electronic Razor, April 1962 Radio-Electronics - RF CafeThe date approacheth when, according to Western customs, every body needs to stand a vigil against the attempt of another body to make him or her a fool. That date is of course April 1st, aka, April Fools' Day. Many of the technical magazine we grew up with - and some still today - engage in the ruse. Innovator and publisher Hugo Gernsback, who's long list of accomplishments includes this Radio-Electronics magazine, often contributed his own wit to the April editions. The usual scheme is to make the article just authentic enough to be possibly real, while including features outrageous enough to clue the read that he is being "had." Experienced subscribers knew that the Mohammed Ulysses Fips byline was sure to deliver an April Fools delight. Here, Mr. Fips expounds on the newfangled "Electronics Razor..."

Photon Entanglement Miniaturizes Quantum Computers

Photon Entanglement Miniaturizes Quantum Computers - RF Cafe"Quantum computing has long struggled with creating entangled photons efficiently, but a team of researchers has discovered a game-changing method using metasurfaces - flat, engineered structures that control light. By leveraging these metasurfaces, they can generate and manipulate entangled photons more easily and compactly than ever before. This breakthrough could open the door to smaller, more powerful quantum computers and even pave the way for quantum networks that deliver entangled photons to multiple users..."

Waveguide Temperature Rise

Temperature Rise in Rigid Waveguide, January 17, 1964 Electronics Magazine - RF CafeHere is a chart you don't see every day - "Temperature Rise in Rigid Waveguide." The company, Engineering Antenna Systems, of Manchester, New Hampshire, that published the chart in a 1965 edition of Engineering magazine, does not exist anymore. They were probably bought by someone else, but I could not even find an honorable mention of them in a Google search. Given the very low attenuation of properly sized and installed waveguide, it is hard to imagine a temperature rise of 500°F; however, when megawatts are pumped into it even a couple tenths of a decibel of attenuation per 100 feet results in a lot of power loss. Noted is how attenuation - and therefore temperature rise - is greater for frequencies at the lower end of the waveguide's operational range. Temperature rise numbers are for natural convection in free air...

everything RF Interviews Ernest Werbel

everything RF's Interview with Ernest Werbel from Werbel Microwave - RF CafeHere is an inspiring interview of Werbel Microwave's Ernest Werbel - a case of pulling oneself up by one's own bootstraps --- everything RF recently interviewed Ernest Werbel, the Chief Design Engineer of Werbel Microwave. He is from Livingston, NJ, and got his associates in EE Technology, at County College of Morris. Ernest completed his Bachelors in Electronics and Computer Engineering Technology from NJ Institute of Technology. He founded Werbel Microwave in 2014. Q. Can you tell us about Werbel Microwave? When did you start the company and how has it evolved over the years? Ernest Werbel: Firstly, thank you for the opportunity to participate in the everything RF community. I appreciate everything that Raghav and his team have done for us since the beginning, getting our products listed on everything RF and featuring our products in the email blasts... As a child and teen in the 90s, I was always interested in electronics. When I was very young, a radio was a magical box with a voice. Later, when my grandparents passed in '97, my parents and I were cleaning out their home in Brooklyn. Among other things were many old and broken consumer electronic items...

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...

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Turn Your Vertical Antenna into a Rotatable Beam

Turn Your Vertical Antenna into a Rotatable Beam (QST) - RF CafeI'm always aware of the old saying that it is better to remain silent and thought a fool, than to open your mouth and remove all doubt, but I'll take the risk here. The ARRL's QST magazine has for decades in the April issue published at least one unannounced "April Fool" item. I think I found at least two for 2025. While enthusiastically reading "Turn Your Vertical Antenna into a Rotatable Beam," (p60), it didn't occur to me that this was the April issue, and I was in awe of Jay Kolinsky's (NE2Q) intuition and creativity in devising a scheme to get directivity from his standard vertical whip antenna. By sliding a carbon fiber tube with a narrow slit along the length over top of the antenna, a 14 dB increase was realized in the direction of the slit. NE2Q has named his invention the Loof Lirpa Slot (LLS). What's in a name - Juliet?. Is a patent in the works?
CW Corporation of America's "Snappy Training Key" - RF CafeThe other suspect is the CW Corp. of America's "Snappy Training Key," reported on page 95 by Ellwood Brem (K3YV). You need to log in to read the articles, or borrow a hard copy from a Ham friend.

Today in Science History

Today in Science History - RF Cafe

Espresso Engineering Workbook™ for Excel

RF Cafe Espresso Engineering Workbook™ for Excel - RF CafeThe newest release of RF Cafe's spreadsheet (Excel) based engineering and science calculator is now available - Espresso Engineering Workbook™. Among other additions, it now has a Butterworth Bandpass Calculator, and a Highpass Filter Calculator that does not just gain, but also phase and group delay! Since 2002, the original Calculator Workbook has been available as a free download. Continuing the tradition, RF Cafe Espresso Engineering Workbook™ is also provided at no cost, compliments of my generous sponsors. The original calculators are included, but with a vastly expanded and improved user interface. Error-trapped user input cells help prevent entry of invalid values. An extensive use of Visual Basic for Applications (VBA) functions now do most of the heavy lifting with calculations, and facilitates a wide user-selectable choice of units for voltage, frequency, speed, temperature, power, wavelength, weight, etc. In fact, a full page of units conversion calculators is included. A particularly handy feature is the ability to specify the the number of significant digits to display. Drop-down menus are provided for convenience...

Shell "Greenhouses" for the Boys "Upstairs"

Shell "Greenhouses" for the Boys "Upstairs", March 23, 1942 Life - RF CafeIn the run-up to World War II and during the battle, a lot of plastics research and production was considered classified defense information. Poly(methyl methacrylate) (PMMA), also know by the trade names of Plexiglas, Lucite, Crystallite, and others, was a crucial component for aircraft where the weight and brittleness of regular glass made it practically useless (and dangerous). A full-page ad by Shell Oil in this 1942 issue of Life magazine promoted plastic used in a bomber. When I see this, it reminds me of "It's a Wonderful Life," where Sam Wainwright offers George Bailey a position in his fledgling soybean-based plastic canopy factory in Buffalo, New York. Being primarily a petroleum product, plastic was promoted heavily by oil companies like Shell Oil, Standard Oil, American Oil, partially due to patriotism, but no doubt also for the profits. Those places, of course, were part of the "Military-Industrial Complex" identified by President Dwight Eisenhower. In fact, an Internet search turns up many claims that those same companies conspired to sell oil to Axis powers prior to America's official entry into WWII on December 7, 1941, when the Japanese bombed Pearl Harbor...

A Short Course in Practical Electronics

A Short Course in Practical Electronics, April 1944 Radio-Craft - RF CafeThe probability-based quantum mechanical model of atoms has been in existence since around 1932 when Robert Mulliken coined the term "electron orbital." It superseded the Bohr model that modeled the atom as a proton/neutron nucleus that was surrounded by electrons orbiting like planets around a star. For many decades thereafter, text books - particularly those used in beginner level courses - continued to present the Bohr model and only gave passing reference, if at all, to the quantum model. The Bohr model was and still is easier for most people to envision, although as time goes on the percentage of people who even recognize a planetary model is probably rapidly decreasing. This article from a 1944 edition of Radio-Craft magazine chooses to use the Bohr model as part of an introduction to electronics. Today, you might need to start from a lower point and talk about groupies swarming around rock stars for most people...

Computing the Harmonic Content of Any Given Periodic Complex Waveform

Computing the Harmonic Content of Any Given Periodic Complex Waveform, Kirt's Cogitations #331 - RF CafeI found a copy of the 1941 Radio Engineering Handbook, by McGraw-Hill Book Company at a Goodwill store. The cover was beat-up, but the inside pages are all good. The "Mathematical and Electrical Tables" section has an interesting method for calculating up to the sixth harmonic of any periodic waveform by dividing the period into twelve equal parts (in time) and noting the amplitudes at each point - aka "The Twelve Ordinate Scheme." Those values are plugged into a host of equations that yield essentially the Fourier coefficients for a 12-element polynomial describing the curve. The text also provides equations for calculating harmonic content. Calculating the polynomial coefficients is a simple process of doing iterations of sums and differences of amplitudes, a la the Fourier analysis. Care must be taken to get the numbers right or the resulting equation will not reproduce the original waveform. In 1941, the user needed to look up in a table or find on a slide rule the sines and cosines of nωt angles associated with each term, then multiply that by the calculated coefficient. Finally, after all twelve points were figured...

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...

Sawtooth Sticklers Quiz

Sawtooth Sticklers Quiz, November 1960 Radio-Electronics - RF CafeHere is an unusual twist in waveform recognition presented by Radio-Electronics' and Popular Electronics' quizmaster, Robert Balin. If you happen to be a former analog television repairman, then you will probably recognize the answers based on your many years of diagnosing faulty horizontal or vertical sweep circuits. If not, then you might need to strain the "little gray cells" a bit, as Agatha Christie's premier sleuth Hercule Poirot might say. The instructions say to assume that if you choose the horizontal sweep sawtooth to be the errant signal, then assume the vertical sweep sawtooth is correct, and vice versa. Right off the bat, waveform 8 is unique enough to easily identify the sweep that would produce it since only one has two repeating components. Most of the others can be readily deduced, too, by mentally following the x and y points as the "correct" sweep...

TV Circuits Crossword Puzzle

TV Circuits Crossword Puzzle, May 1958 Radio News - RF CafeIf you happen to be a retired television repairman from the era of analog broadcast and cathode ray tube (CRT) displays, or if you have studiously read the many articles I have posted from vintage electronics magazines about TV, then you will probably breeze right through this themed crossword puzzle from a 1958 issue of Radio & TV News. I have to admit to having done poorly myself, even after having been the one who posted all that stuff. Just having a general knowledge of electronics doesn't help much here since all the clues and words are very specific to television circuits. Still, it's worth the challenge and if nothing else you'll learn a little more about old time television- it really was a quite ingenious scheme for cramming ...

Behind the U.L. Label

Behind the U.L. Label, August 1955 Popular Electronics - RF CafeThe Underwriter's Laboratory (UL) is an entity that seems to have been around forever. A lot of people - maybe most people - assume that it is a government entity. In fact, it is a non-profit organization sponsored by the National Board of Fire Underwriters (later changed to American Insurance Association, then to APCIA). Its roots are traceable back to the Chicago World's Fair in 1893. Concern over the potential fire hazard of Edison's light bulbs was the impetus for the effort. Another aspect of the UL that a lot of people don't know is that the UL label of approval is no guarantee that the device works properly, only that is passes standards of safety as it relates to fire hazards. This article in the August 1955 edition of Popular Electronics magazine gives a brief history.

Electronics-Themed Comics

Electronics-Themed Comics, July 1945 Radio & Television News - RF CafeIf you like the radio-themed comics from vintage electronics magazines, then you'll appreciate the jackpot of them (5) in the July 1945 issue of Radio Craft magazine. Being the era in which it was published, many of the comics at the time had military-electronics themes as well. A lot of them are credited to subscribers providing ideas. One of my favorite features is "Radio Terms Illustrated," where readers write in with suggestions for how common lingo in the radio realm can have an alternate interpretation. Such is the case with "Wave Trap" in the first comic. I think Frank Beaven was the illustrator for all of them. Look in the big list of other technical-themed comics at the bottom of the page for others which include "Radio Terms Illustrated."

Changing the Light Bulb on a 1,500' Tower - A Drone's-Eye View

Changing the Light Bulb on a 1,500' Tower - RF CafeBack in 2012, I posted a video of the PBS "Frontline" show (Cell Tower Deaths) that highlighted the dangers cell tower climber technicians face while working for very low wages. Other news stories since then have reported on new regulations from OSHA and other agencies that have helped make the safety issue better, but I haven't seen anything on whether the pay has gotten any better. There are lots of videos and photos online of tower climbers all over the world, but this one showing tower climber Kevin Schmidt making the ascension to the very top of the now inactive KDLT TV analog broadcast antenna near Salem, SD, is unique in that the recording was made from a drone platform. It has more than 12 million views. Capturing this kind of video requires a drone with a wireless live feed so the pilot...

1957 Popular Electronics Crossword Puzzle

Crossword Puzzle, October 1957 Popular Electronics - RF CafeHere is a vintage crossword puzzle from the October 1957 edition of Popular Electronics magazine. Being created at a time solidly into the semiconductor era, you do not need a knowledge of vacuum tube terminology. This one contains mostly words relating to electronics similar to the weekly electronics, math, science, technology, and RF & microwave theme crosswords from RF Cafe. It won't take you too long to complete...

Espresso Engineering Workbook™ for Excel

RF Cafe Espresso Engineering Workbook™ for Excel - RF CafeThe newest release of RF Cafe's spreadsheet (Excel) based engineering and science calculator is now available - Espresso Engineering Workbook™. Among other additions, it now has a Butterworth Bandpass Calculator, and a Highpass Filter Calculator that does not just gain, but also phase and group delay! Since 2002, the original Calculator Workbook has been available as a free download. Continuing the tradition, RF Cafe Espresso Engineering Workbook™ is also provided at no cost, compliments of my generous sponsors. The original calculators are included, but with a vastly expanded and improved user interface. Error-trapped user input cells help prevent entry of invalid values. An extensive use of Visual Basic for Applications (VBA) functions now do most of the heavy lifting with calculations, and facilitates a wide user-selectable choice of units for voltage, frequency, speed, temperature, power, wavelength, weight, etc. In fact, a full page of units conversion calculators is included. A particularly handy feature is the ability to specify the the number of significant digits to display. Drop-down menus are provided for convenience...

Natural Code Non-Ambiguous Optical Encoder

Wayne-George Corporation Advertisement, February 28, 1964 Electronics Magazine - RF CafeAdmittedly, the only thing I remember about Gray Code (aka reflected binary) from college courses is that successive count values change only one bit per increment, saving power in some digital circuits. The power savings comes from the fact that, especially for CMOS circuits, current only flows during the transition of a state change from "0" to "1" or from "1" to "0." Shaft position encoders were and still are a primary application of Gray Code switching. If the encoder output digital code is going to be used in a binary computation system, then there is an advantage in generating a direct binary ("natural") count that does not require a Gray-Code-to-Binary conversion circuit (or software routine). When the Wayne-George Corporation introduced its paradigm-changing "Natural Code Non-Ambiguous Optical Encoder" in 1964, those conversion circuits were probably not simple, compact, inexpensive semiconductor IC's...

Can You Pay Yourself a Salary?

Can You Pay Yourself a Salary?, June 1952 Radio & Television News - RF CafeThose of you who have or have had a business where you employed workers can relate to this article which appeared in a 1952 issue of Radio & Television News magazine. Never having had that responsibility, I cannot relate directly. Small business owners I have known have told me about how their first responsibility is to pay employees before paying themselves, and no one who has never been in that position can truly relate to it. What I find interesting in these kinds of vintage articles is the cost of goods and services back in the day, with the help of the Bureau of Labor Statistics' Inflation Calculator. For instance $100 per week ($5,200/year) income back in 1952 is supposedly equivalent to $1,024 per week ($53,248/year), which really is pretty good. I don't know how generous fringe benefits were in 1952 compared to today...

Calls Home from Auto

Calls Home from Auto by Short Wave, August 1935 Short Wave Craft - RF CafeThis could be one of the earliest reports of mobile communications between a private automobile and a home base station. Using a personally designed and installed 5-meter transceiver both at home and in his car, Mr. Wallace is able to talk to his 12-year-old son on the way from work. My guess is that in 1935 there were not too many traffic jams, even in Long Beach, California, so it is doubtful that was the cause for his announced expected later-than-normal arrival home. The article states the automobile power supply needed to produce 300 mA of current at 525 V, which is ~160 W per Ohm's law, which seems unlikely considering car batteries were 6 V at the time...

Is Fair Trade the Answer to TV Price Cutting Problem?

Is Fair Trade the Answer to TV Price Cutting Problem?, October 1949 Radio & Television News - RF Cafe"Fair Trade" was a policy established in the post-WWII era in response to what consumer retail groups considered business-ruining cost cutting by dealers who offered to sell products at or barely above cost in order to steal profit from other stores. So-scheming stores planned to make up for the low profit margin with high sales volumes. Doing so drove a lot of the local competition out of business, leaving the crafty dirty dealers to later raise prices. Stores that had manufacturer-sanctioned service shops often got screwed because they were obligated to repair items like TVs and radios that were bought from another dealer who did not do service work. Profit margins on repair work - at least from honest shops - were typically very low, so the owners depended on new product sales to help raise the bottom line...

Calculus and Its Application in Radio

Calculus and Its Application in Radio, March 1933 Radio News - RF CafeIt has been a while since I saw the quotient rule for derivatives applied. Probably the last time was in a college text book, because I'm pretty sure I haven't had the occasion to use it since then - except maybe back in the days when I was writing my RF Workbench software and needed to derive closed form solutions for group delay in filters. This 1933 article from Radio News magazine presented the quotient rule as part of a discussion for finding the impedance of a load for maximum power transfer. Pure resistances were used in the example, but the method applies as well to complex impedances...

Quiz on AC Circuit Theory

Quiz on AC Circuit Theory, December 1970 Popular Electronics - RF CafeHere is a fairly simple quiz on AC circuit analysis. If you are not already comfortable with adding series and parallel circuits containing resistors, capacitors, and inductors, you will appreciate the simple formula presented that will keep the sweat level down ;-) . An even simpler form that solves explicitly for the four variables are as follows:

VTotal = √ [(VL - VC)2 + VR2]

VR = √ [(VT)2 - (VL - VC)2]

VL = VC + √ [VT2 - VR2]

VC = VL - √ [VT2 - VR2]

    OK, pick up your pencils... now...

Radium-Radio Receiver

Radium-Radio Receiver, April 1944 Radio-Craft - RF Cafe"Necessity is the mother of invention," is a common saying that proves itself to be particularly true in times of war. World War II launched scientists and engineers belonging to both the Axis and the Allied powers into inventive frenzies in their efforts to hasten an end to hostilities; of course each side also wanted to be the victor. We all know how the story ended. Although some countries were not immediately able to capitalize on their countrymen's technical advances, within about a decade normalized relations had been established between former foes, and the exchange of products, services and scientific information proceeded. Some discoveries were deemed too valuable to national security and were therefore not divulged even, in some instances, to friendly nations. Many scientists consider themselves to be "citizens of the world" and vehemently object to not sharing all available knowledge out of a belief...

Allied Radio: Hallicrafters Receivers

Allied Radio: Hallicrafters Receivers, April 1941 Radio News - RF CafeLittle did Ham radio operators know in April of 1941 when they were enthusiastically buying equipment for their shacks that a year later the Federal Communications Commission (FCC) would ban them from broadcasting from their transmitters. This advertisement for a high-end Hallicrafters receiver appeared in the April issue of Radio News magazine. Part of the feature definition includes "calibrated bandspread inertia controlled," and "micrometer scale tuning inertia controlled." I'm not sure what the "inertia controlled" part is, unless it refers to how massive metal disks were sometimes installed inside the chassis on the tuning shaft in order to give a more solid feel to the control knob, as well as to enable the dial to be spun and released to rapidly move through a large distance between adjustment points...

Great Britain Interference Survey

Great Britain Interference Survey, November 1976 QST - RF CafeWhen I began reading this piece I wasn't sure whether it was reporting on interference caused to amateur radio operation or interference caused by amateur radio operation. It turns out to be the latter. Ever since radio operation began in the days of Marconi, unintentional interference has been a problem. The problem has always been a combination of improper transmitter and/or receiver filtering. Electromagnetic spectrum regulatory agencies attempt to assess and address interference through operational band assignments for particular segments of the spectrum, including how much residual (unintentional) power can be emitted outside of band or within a defined power mask. Amateur radio operators are often the first group to be suspected of causing interference, no doubt due to the "amateur" part of their moniker. In truth, many amateurs are some of the most knowledgeable and responsible users of the airwaves...

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