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Today in Science History

Howard W. Sams Photofact "Win-a-Mustang" Contest

Howard W. Sams & Co., Inc. Photofact "Win-a-Mustang" Contest, December 1964 Radio-Electronics - RF CafeSam's Photofact® was the world's premier publisher of service documentation for nearly every make and model of radio, television, tape deck, projector, phonograph, and other domestic type products. By 1964 when this ad appeared in Radio-Electronics magazine, a service shop which owned a copy of every service pack ever printed had probably half a dozen file cabinets filled with folders. Manufacturers typically did not make such information available to the general public or even to shops that did not have service agreements with them. Except for some condensed versions published by magazines, and a couple other minor datapack vendors, Sam's was it. A contest drawing was used when the Ford Mustang first came out that offered a free car to the first place winner. As the ad thumbnail shows, the initial MSRP for the 1965 Mustang was a whopping $2,368 --- the equivalent of about $23,408 in 2024 money. That, of course, was the base price. It's hard to believe, but the base 2024 Mustang is only $30,920. That's 32% more than the 1965 base model, but the base today has a lot more features than in 1965. Fortunately, the new Mustangs do not feature an explode-on-impact gas tank behind the rear seat...

Dig That Reel Flat Response!

Dig That Reel Flat Response!, May 1956 Popular Electronics - RF CafeThis 1956-vintage Popular Electronics magazine article by techno-kidder Carl Kohler taught me a new word - "darb," as in "Isn't that a darb, now." According to Merriam-Webster, a darb is a slang term for something superlative. Mr. Kohler penned many tongue-in-cheek stories for Popular Electronics in the 1950s and 1960s, all of them based on his antics involving the latest electronics gadget and Mrs. Kohler's reaction to them. Maybe they are real (in this case, "reel") and maybe not, but regardless, they are funny and even if made up, could easily be actual experiences. A list of the other Kohler sagas is given below...

Dumb Move Spawned the x86 and Kickstarted PC Revolution

How a Dumb Move Spawned the x86 and Kickstarted the PC Revolution - RF Cafe"What was once considered a bad business venture, the 8008's lasting legacy went on to drive the technological world we live in today. Computer Terminal Corporation (now defunct Datapoint) launched the DataPoint 3300 computer terminal in 1969 as a platform to replace teleprinters, or the precursors to fax machines. The machine was implemented using TTL logic in a mix of small- and medium-scale integrated circuits (ICs), which could produce an enormous amount of heat during operation. When the terminal was announced in 1967, RAM was extremely expensive (and heavy). So, the DataPoint terminal stored its display of 25 rows of 72 columns of upper-case characters using fifty-four 200-bit shift registers, arranged in six tracks of nine packs each, providing shift register memory for 1,800 6-bit characters. To address the excessive heat and other issues, CTC designed the DataPoint 3300's predecessor with a CPU, placing all of those ICs on a single chip. CTC co-founder Austin Roche looked to Intel to help with the endeavor, as the company was well known for being a primary vendor of RAM chips at the time..."

Thin TV Display Panel

Thin TV Display Panel, January 1973 Popular Electronics - RF CafeAlthough not routinely referred to as plasma displays at the time, the "thin TV displays" reported in this 1973 article in Popular Electronics magazine was one of the first instances of commercially viable schemes. According to Wikipedia, Fujitsu introduced the first full-color plasma display panel (PDP) in 1992 - with a 21" screen - two decades after this device 80x212-pixel monochrome designed by Zenith. I remember seeing the 42" Fujitsu plasma TVs in Best Buy with a $10,000 price tag sometime in the mid 1990s, which jives with Fujitsu's stated plan of selling the first units at around 1 million yen (~$8,800 at today's exchange rate). Prior to the advent of plasma displays, rear-projection screen televisions were the main way to get really large displays. While rear-projection displays suffered from narrow viewing angles, plasma displays suffered from pixel burn-in that gradually reduced contrast to annoyingly low levels. Both options carried a relatively large price tag compared to 25" and 27" CRT televisions...

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...

In's and Out's of Lead-Ins

In's and Out's of Lead-Ins, August 1967 Radio-Electronics - RF CafeMy family's house where I grew up (well, got older) was probably typical of most when it came to mounting television antennas on the roof and running the twin−lead, 300-ohm transmission cable down to a point where it entered the house, and then from there to the TV set. In retrospect, it was a miracle the system worked any better than just hooking up the rabbit ears on top of the set. If nothing else, it demonstrated how much better a roof-mounted antenna was than just rabbit ears (unless you lived very close to the broadcast tower). If I remember correctly, the first picture in the article showing how "not" to run your cable into the house is the way we did it. I didn't even know there was a socket and plug available for the twin−lead, nor did it occur to me or my father that drilling a hole through the side of the house was an option (our house had too many unplanned holes as it was). This 1967 Radio−Electronics magazine article covers the basics of the proper method for routing the twin-lead cable. While it does mention the use of impedance matched power splitters, no instruction is offered on why or how to do it. Neither is there mention of the need to properly terminate unused jacks in order to keep everything working at an optimal level...

The Rechargeable Alkaline Battery

The Rechargeable Alkaline Battery, November 1972 Popular Electronics - RF CafeNickel cadmium (NiCd or NiCad) and nickel metal hydride (NiMH) batteries are classified as secondary cells because they are rechargeable. Primary cells like carbon and standard alkaline are not rechargeable. Those were the most common types of batteries- at least for consumer products - up through the late 1980s. The now-common lithium ion (Li-Ion or LiIon) and lithium polymer (Li-Po or LiPo) are also secondary types. Devices designed to use either lithium chemistry are meant to work at integer multiples of the nominal 3.7 V cells potential. In the mid 1980s, when NiMH was gaining popularity as a high energy density rechargeable battery, a lot of people (including myself) began using them instead of standard alkaline batteries in cameras, radios, toys, etc. The problem was, though, that both NiCd and NiMH cells have a nominal voltage of just 1.2 V, which meant that the operation time of the device was often less than with a disposable alkaline or carbon battery. A lot of electronic devices designed for 1.5 V per cell barely function at 1.2 V. Rechargeable alkaline batteries, which still had a 1.5 V nominal voltage, were/are the compromise solution to that scenario. Energy density of an alkaline compared to a NiMH battery is typically much less, but they still provide better economy than using disposable batteries...

"NASA Spinoff" Technology Transfer Program

NASA Technology Transfer Program - RF CafeEver since the manned space exploration programs began at NASA (National Aeronautics and Space Administration), controversy over both the financial costs and the cost in lost opportunity for other government funded programs has existed. Many people, myself included, have always championed the efforts and believe the axiom of the whole being greater than the sum of the parts applies to the efforts. Opponents say resources would be better spent here on Earth. In fact, we have always done both. To address the issue, NASA Spinoff was created to publicize the byproducts of the space program that benefit other areas of research, manufacturing, and society. Since at least the 1970s, NASA has published a monthly magazine entitled NASA Tech Briefs to inform the public on their activities, inviting readers to submit ideas and to request information on how to apply NASA research to commercial applications. I have been a regular reader since around 1980...

The Challenge of Slow-Scan TV

The Challenge of Slow-Scan TV, August 1973 Popular Electronics - RF CafeYou would be forgiven if you think a technology as crude as slow-scan television (SSTV) has gone out of vogue with live YouTube videos and webcams, but such is not the case. What has changed is the portion of Amateur Radio spectrum allocated to SSTV and which classes of license holders may use it. Of course the equipment used has been modernized, but vintage systems still work. Originally, only Advanced class ticket holders were allowed access, but nowadays all Hams may operate SSTV, including the entry level Technician class. SSTV was used extensively on space exploration platforms including Apollo; in fact the historic Apollo 11 video feed of astronauts Armstrong and Aldrin hopping around on the moon were transmitted via SSTV. ARISS (Amateur Radio on the International Space Station) regularly transmits via SSTV...

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...

Phase, Feedback and Instability

Phase, Feedback and Instability, December 1964 Radio-Electronics - RF CafePhase, feedback, and instability, which happens to be the title of this 1964 Radio-Electronics magazine article, has never been my forte. The controls course I had in college was one of the most challenging of all, along with semiconductor physics. For some reason, I had trouble figuring out how to construct the formulas properly in the more complex systems. It was an intensive exercise in applying LaPlace transforms. Controls class was one of the very few courses in which I did not receive at least an A-. Anyway, the math presented in this article is very basic and will not be a stumbling block to understating the basic principle of feedback. You cannot study feedback and instability without being comfortable with a little geometry and trigonometry, so be prepared. Author Crowhurst does not get into poles and zeroes in the right-half and left-half regions of the complex plane, so that will prevent a few anxiety attacks from his readers ;-) ...

Monocrystalline Gold Electronic Devices Near Efficiency Limit

Monocrystalline Gold Electronic Devices Near Efficiency Limit"Gold has long been a popular way of enhancing the photosensitivity of electronic devices such as biosensors, imaging systems, energy harvesters and information processors. So far, the gold used has been polycrystalline, but in the past few years various research groups have finessed techniques for producing monocrystalline gold. Researchers led by Anatoly Zayats at King's College London, UK and Giulia Tagliabue at École Polytechnique Fédérale de Lausanne in Switzerland are now reporting that electrons in these new monocrystalline gold films behave significantly differently from electrons in polycrystalline gold. 'We had surprises that we did not expect,' Zayats tells Physics World. The differences, he adds, could bring significant benefits for applications. Gold makes a useful photosensitizer because it supports a resonant response in which the oscillating electromagnetic field of the incident light makes electrons slosh back and forth collectively. This collective motion is termed a plasmon, and as the oscillation comes out of phase, energy in the plasmon passes on to electrons and positively-charged holes in the gold. Thanks to this transfer of energy, the electrons develop an effective temperature much higher than the material's equilibrium temperature. It is these 'hot' electrons that are so useful at initiating chemical reactions, signaling photon detection, stashing energy and so on..."

TV Show Features "Wires and Pliers"

TV Show Features "Wires and Pliers", April 1956 Popular Electronics - RF CafeWhen I first saw this picture of Dr. Martin L. Klein, I though he was Superman. No, it doesn't take a superman to teach electronics on television, but the familiarity of George Reeves as the star of the "Adventures of Superman" series in from 1953 through 1958 would have been a good reason to use him in the "Wires and Pliers" TV show. Dr. Klein and his techie sidekick Aram Solomonian performed a weekly show presenting basic electronics to the audience. BTW, as long as I am on a roll with misidentifications, I also looked up whether Dr. Klein is related to the Klein Tools family. Klein has long been a producer of very high quality hand tools for electricians (and others), hence, wires and pliers. Alas, wrong on that one, too. I still own and use the Klein lineman's pliers, dikes, screwdrivers, etc., that I bought nearly five decades ago when first entering the realm of electricianhood [sic]...

Anatech Electronics February 2024 Newsletter

Anatech Electronics February 2024 Newsletter - RF CafeSam Benzacar of Anatech Electronics, an RF and microwave filter company, has published his February 2024 newsletter that, along with timely news items, features his short op−ed entitled "Satellites Join Terrestrial 5G," in which he summarizes the state of the art for satellite direct to cell[phone] (DTC) communications. The massive satellite constellations that are beginning to clutter the night sky (and the day sky, but that doesn't matter much to visible light astronomers) have orbits low enough to make signal travel time latency negligible compared to the quarter second or so for geostationary satellites. LEO satellites be at around 330 miles above sea level and geostationary be at around 22,236 miles, so LEO latency is roughly 2% that of geosynchronous. Of course the latency also depends on how far from the phone's zenith the satellite lies. While data rates for the mini Earth stations with a parabolic dish are in the neighborhood of 10-20 Mbps, for a cellphone the rates are good enough for text messaging (SMS), but that's about it. It's considered by many to be an emergency mode at this point in DTC communications...

Volta and His "Electric Pile"

Volta and His "Electric Pile", January 1973 Popular Electronics - RF CafeThis 1973 Popular Electronics magazine article has got to be one of the most concise and interesting summaries published of Alessandro Volta's path to the discovery of battery cells, aka "piles." Author David Heiserman covers not just the technical aspects of Volta's experiments, but the personal and political tip−toeing he needed to endure with contemporary physicist Luigi Galvani and conqueror Napoleon Bonaparte, respectively. Alas, that has been the case throughout history regarding not offending certain powerful people. Although such unnecessary struggles continue to impede scientific advancement, at least the unfettered access to the Internet has provided a venue for otherwise undiscoverable work to be aired. Today, though, while you might not be tortured, imprisoned, or murdered for your work, you can still be "cancelled" through delisting, denying access to funds, blocking, and any number of other nefarious tactics.

Get Your Custom-Designed RF Cafe Gear!

Custom-Designed RF-Themed Cups, T-Shirts, Mouse Pads, Clocks (Cafe Press) - RF CafeThis assortment of custom-designed themes by RF Cafe includes T-Shirts, Mouse Pads, Clocks, Tote Bags, Coffee Mugs and Steins, Purses, Sweatshirts, Baseball Caps, and more, all sporting my amazingly clever "RF Engineers - We Are the World's Matchmakers" Smith chart design. These would make excellent gifts for husbands, wives, kids, significant others, and for handing out at company events or as rewards for excellent service. My graphic has been ripped off by other people and used on their products, so please be sure to purchase only official RF Cafe gear. I only make a couple bucks on each sale - the rest goes to Cafe Press. It's a great way to help support RF Cafe. Thanks...

Mathematical Puzzles, 1985 OFA

Mathematical Puzzles, 1985 Old Farmer's Almanac - RF CafeHere is another set of "Old and New Mathematical Puzzles," compliments of the 1985 edition of the Old Farmer's Almanac. All of the puzzles from Difficulty 1 through Difficulty 3 can be worked out without much trouble. Puzzle number 3 is a variation on an optical illusion based on the Möbius strip, or maybe more like a Klein bottle. Of course, being a farmer thing, there's a puzzle involving the number and price of produce at the market. There are four Difficulty 5 puzzles for which no solutions are given. They are the ones where readers are invited to submit solutions, and the winner for each receives a $50 award and honorable mention in the next year's edition. The winning solutions are never shown, but you can write to request a copy of them. It would be interesting to see what the solutions look like for this year's puzzle 13. You need to be good at three-dimensional drawing to render them...

Comic with an Electronics Theme

Comic with an Electronics Theme, June 1972 Popular Electronics - RF CafeClose out this day with a tech-themed comic from a 1972 issue of Popular Electronics magazine (only one this time). Those of you who entered the engineering realm sometime after the 1990s might not recognize the strange looking surface the guy is sitting behind. It was an early tabletop touch-type display where the stylus with which the user created an image (drawing) was a wooden stick with a round shaft of graphite located coaxially in the center. The pointed, relatively soft tip wore down rather quickly and required frequent reshaping to maintain a constant pixel width in the lines. Portions of drawings made on those devices could only be erased and redrawn a few times as with modern solid-state drives. Cutting and pasting required physical cutting and pasting (or taping). Clipboards were often used to hold frequently replicated snippets of renderings (title blocks, standard drawing notes, etc.) for pasting into a drawing. One big drawback of those older drawing programs was that after a day's work you usually went home with a layer of graphite on your palm and shirtsleeve...

Silicon Electro-Optical IC Narrowband Multi-GHz Filtering

Silicon Electro-Optical IC Narrowband Multi-GHz Filtering - RF Cafe"It's a very safe bet that a wireless or wired system uses at least one filter - and likely many more - in their various forms: low-pass, high-pass, notch, or bandpass. As operating frequencies increase into the gigahertz and tens of gigahertz range, it's increasingly difficult to create filters with narrow bandpass or notch performance, especially using discrete-device versions which are almost always impractical in that range. While there are ways to create such filters using surface-acoustic-wave (SAW) and bulk-acoustic-wave (BAW) technologies, even these technologies struggle to keep up with the demands for narrow bandwidth filtering at these ever-higher frequencies. Recognizing the need and opportunity, the photonic and electro-optical (E-O) community is doing a great deal of research to overcome these barriers. For example, researchers at the University of Sydney (Australia) Nano Institute devised a compact semiconductor chip that provides for the heterogeneous integration of chalcogenide glass with silicon to create specialty filters. Their effort has resulted in a notch filter with narrow 37-MHz 3-dB bandwidth..."

RF Energy Powers Incandescent Lamp

R.F. Energy Powers Incandescent Lamp, April 1956 Popular Electronics - RF CafeWireless power distribution has been in the news a lot for the last few years. It began with a goal of just wirelessly charging mobile devices like cellphones, smart watches, and tablet computers. Next came articles about charging electric cars wirelessly while sitting in a parking lot or garage, or even at a stop light. In each instance, the item being charged needed to sit in close proximity to an electric induction coil to be effective. Just a couple days ago, however, a new item appeared where Disney Research has come up with a "quasistatic cavity resonance" system that covers an entire room. This story from a 1956 edition of Popular Electronics magazine reports on an incandescent lamp powered wirelessly by an RF energy source. It's not quite the same thing, but is the same basic principle...

RF & Electronics Stencils for Visio

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

More Meters for Beginners

More Meters for Beginners, December 1964 Radio-Electronics - RF CafePrior to the advent of meters with a super high input impedance (>1 MΩ) featuring field effect transistors (FETs), accurate use of a voltmeter or ohmmeter required knowledge of the meter's internal resistance and the resistance of the device under test (DUT). As can be seen in Figure 2, various range settings on the meter resulted in different internal resistances. The internal resistance of the meter in series with the resistance of the DUT form a voltage divider where the indicated voltage is less than that which would be indicated if the meter's internal resistance was much higher. Author Robert Middleton presents examples of possible errors when measuring voltage, current, and resistance. Many modern digital multimeters (DMMs) have an input impedance of at least 10 MΩ, so very few scenarios would require minding the meter characteristics. With DMMs there is also no need to learn how to interpret the multiple needle scale markings, or to take care to avoid parallax error as a result of not looking at the needle from directly perpendicular to the scale markings, or keeping track of the reading units (mV, V, mA, A, Ω, kΩ, MΩ...

Transistor Topics

Transistor Topics, January 1956 Popular Electronics - RF CafePopular Electronics magazine ran their "Transistor Topics" column for many years, and this is the third in the series. Unfortunately, I do not yet have the previous two editions, but someday... Transistors were a relatively new phenomenon at the beginning of 1956, so there was a lot to learn and a lot of people to teach about them. It might have been easier to make converts of dedicated tube users if the JFET (junction field effect transistor) had been commercialized before the BJT (bipolar junction transistor), since the JFET (voltage on the gate controls current flow) acts more like the familiar vacuum tube (voltage on the control grid controls current flow) than the BJT (current on the base controls current flow)...

Integrated Satellite with Mobile Devices

Integrated Satellite with Mobile Devices - RF Cafe"The formation of the Mobile Satellite Services Association (MSSA) marks a significant stride towards enhancing global connectivity through the emerging Direct-to-Device (D2D) and Internet of Things (IoT) services. Leading entities in the satellite communications sector, including Viasat, Inc., Terrestar Solutions, Ligado Networks, Omnispace, and Al Yah Satellite Communications Company PJSC (Yahsat), have come together to establish this non-profit industry consortium. The MSSA's mission is to harness over 100 MHz of L- and S-band spectrum-already allocated and licensed for mobile satellite services (MSS)-to build a robust global ecosystem that integrates seamlessly into a wide array of mobile devices. The Association's alignment with 3rd Generation Partnership Project (3GPP) standards is a critical move to broaden terrestrial mobile coverage, including for Mobile Network Operator (MNO) and Over-the-Top (OTT) internet services. This strategic initiative underscores the inherent advantages of MSS licensed spectrum, such as the capability for existing space networks to instantly provide Narrowband Internet of Things (NB-IoT) services..."

Electronics Crossword Puzzle

Electronics Crossword Puzzle, March 1973 Popular Electronics - RF CafeRegular RF Cafe visitors know I have a penchant for creating and solving crossword puzzles. Since around 2001, I have personally generated a new crossword almost every week - hundreds in total. Some studies have suggested lower rates of dementia in people who regularly exercise their brains, but that is not the primary reason I work crossword, word scramble, and Sudoku puzzles - I enjoy the challenge. A couple times each year, Popular Electronics magazine published an electronics-themed crossword puzzle; however, unlike the crosswords I make, not all of the words and clues have to do with technology and science. Still, they're a good pastime activity...

Promote Your Company on RF Cafe

Sponsor RF Cafe for as Little as $40 per Month - RF CafeBanner Ads are rotated in all locations on the page! RF Cafe typically receives 8,000-15,000 visits each weekday. RF Cafe is a favorite of engineers, technicians, hobbyists, and students all over the world. With more than 17,000 pages in the Google search index, RF Cafe returns in favorable positions on many types of key searches, both for text and images. Your Banner Ads are displayed on average 280,000 times per year! New content is added on a daily basis, which keeps the major search engines interested enough to spider it multiple times each day. Items added on the homepage often can be found in a Google search within a few hours of being posted. If you need your company news to be seen, RF Cafe is the place to be...

Westinghouse Radio

Westinghouse Radio, August 13, 1945 Life - RF CafeWestinghouse, headquartered in and around Pittsburgh, Pennsylvania, was a major force in all aspects of commercial broadcast radio. The company designed, manufactured, installed, and managed broadcast studios and transmission equipment. They also made some of the greatest complexity and quality receivers. Many were truly masterpieces that complimented rooms outfitted with high end furniture. Other companies like Crosley also made very large, multi-featured consoles with record-changing phonographs, AM and shortwave receiver bands with pushbutton tuning, AGC and AFC circuits, ample storage space for records, built-in antennas, AC or DC operation, and other bells and whistles. Curvaceous solid and plywood construction was solid and finishes had a deep luster. This full-page 1945 Life magazine advertisement was a pitch for what would have been one of the first new radios sold at the end of World War II, during which all resources had been dedicated to military equipment thanks to the War Powers Act of 1941. Although not mentioned, I'm guessing the girl is the daughter of either John Charles Tomas or Ted Malone...

Plasma Stealth Device Takes Aircraft off the Radar

Plasma Stealth Device Takes Aircraft off the Radar - RF Cafe"A new-generation plasma stealth device that can make almost any military aircraft vanish from a radar screen is claimed to have been developed by a team of scientists and engineers from western China. Unlike its predecessors, which generate a cloud of plasma draped over a plane, this innovation can be tailored to fit a sensitive section of a military aircraft - areas like the radar dome, cockpit or other spots that are most prone to enemy radar detection. This 'closed electron beam plasma stealth device,' which focuses on protecting key areas instead of the entire aircraft, can be switched on at a moment's notice to fool radar operators. It has many advantages such as 'simple structure, wide power adjustable range and high plasma density,' Tan Chang, a scientist involved in the project, wrote in a peer-reviewed paper published in the Chinese Journal of Radio Science in December. Chinese scientists say they can use foreign military radar to track ships. Plasma, composed of electrically charged particles, interacts with electromagnetic waves in a unique way. When electromagnetic waves - such as those emitted by radar - interact with plasma, they cause the particles to move rapidly and collide, dissipating the waves' energy and reducing the strength of the reflected signal. This interaction converts the energy... (line 546 in page source view for non-subscribers)

Transistor Selection Guide for Experimenters

Transistor Selection Guide for Experimenters, June 1974 Popular Electronics - RF CafeBelieve it or not, there are still people out there - engineers and hobbyists - who design circuits using discrete transistors. Sure, there is a plethora of integrated circuits that combine multiple functions into a single package that performs often nearly like ideal components, and for a lot less money than building an equivalent circuit from individual components. Still, sometimes a lone transistor with a couple biasing resistors will do the job, and sometimes the designer just wants to do something different. There are also plenty of instances where you need to find a replacement of a failed transistor that has similar form, fit, and function. This article from a 1974 issue of Popular Electronics magazine might be just the aid you need if you have found yourself in need of selecting a transistor. Of course if your application is for high frequency, there are parameters to consider other than those presented here, but it's a good start...

Home-Brew Double Balanced Mixer

Home-Brew Double Balanced Mixer - RF CafeDouble-Balanced Mixer Schemtatic - RF CafeWhen RF Cafe visitor Ed W. saw the photo I posted of the très cool looking miniature isolation transformers from "Exploring Uncommon Applications of Isolation" it reminded him of a double balanced mixer his company designed back in the 1970s for a line of high frequency (HF) radios like the Cubic Astro 200. At the time, it was considered more economical than a commercially made mixer. Unless exceptionally high power handling is required, a modern integrated double balanced mixer like this one from Marki Microwave will have better higher performance because the diodes will all be nearly perfectly matched. The same is true, of course, for triple balanced mixers. Double balanced mixers tend to suppress odd order spur products to a greater degree than even order products, while triple balanced mixers tend to suppress even order spur products to a greater degree than odd order products.

Sylvania General Telephone and Electronics

Sylvania General Telephone and Electronics Ad, February 1970 Popular Electronics - RF CafeIn 1970, Sylvania ran this 2-page advertisement in Popular Electronics magazine touting the accomplishment of reducing the equivalent of 60,000 discrete components to a mere 60 - thanks to integrated circuits. That 1,000:1 ratio is miniscule compared to this year (2017) where AMD's 24-core EPYC 7401P sports 19,200,000,000 transistors. If Moore's Law continues, we can expect nearly 40 billion in another year and a half. Sylvania was not claiming to be able to replace all components with integrated circuits, just to drastically reduce the number of parts needed to stock for prototyping and production. Even AMD's gigaprocessor needs a large handful of capacitors sprinkled around its periphery to function in the presence of electrical noise and power fluctuations, and also a few steering diodes and pull-up resistors. I don't dare make a statement like, "There will always be a need for discrete passive components," because bioelectronics might easily replace both discrete and integrated components with gelatinous blobs of synapse-filled gray matter, powered by pseudo stomachs fed by frankenpellets of nutrition...

RF Cascade Workbook

RF Cascade Workbook - RF Cafe RF Cascade Workbook is the next phase in the evolution of RF Cafe's long-running series, RF Cascade Workbook. Chances are you have never used a spreadsheet quite like this (click here for screen capture). It is a full-featured RF system cascade parameter and frequency planner that includes filters and mixers for a mere $45. Built in MS Excel, using RF Cascade Workbook is a cinch and the format is entirely customizable. It is significantly easier and faster than using a multi-thousand dollar simulator when a high level system analysis is all that is needed...

News Briefs: Telephone Switching Networks & Fluid Amplifiers

News Briefs: Telephone Switching Networks & Fluid Amplifiers, December 1964 Radio-Electronics - RF Cafe"Semipermanent" magnetic memory is reported here in this 1964 Radio−Electronics magazine news item. The term semipermanent is an awfully good, clearly confusing, but seriously funny example of an oxymoron, akin to jumbo shrimp, old news, random order, and unbiased opinion. An electronic switching system is announced which will replace the massive network of electromechanical switches in the nation's telephone system. Once implemented, the cacophony of clicking relays heard inside the switch rooms containing thousands of of the noisy little buggers would go silent. I remember being in such a facility in the mid-to-late 1970s where the electromechanical relays were still being used, so it was well over a decade before a total switchover (see what I did there?) was completed. Also covered was a computer built by Univac that used fluid amplifiers (literally a fluid, including air). Also, there was news of the "World's Greatest Amateur," John L. Reinartz, W1XAM, having attained Silent Key status...

New Radio Rucksack for U.S. Army

New Radio Rucksack for U.S. Army - RF Cafe"The Army is testing a new rucksack that was purpose-built for radio operators to reduce damage to systems on drops, add space, improve fit and cut down on heat. The Radio Carrier Rucksack was assessed in airborne drops with soldiers at Yuma Proving Ground, Arizona, according to an Army release. The radio ruck is being developed by Natick Soldier Systems Center under the Army's Combat Capabilities Development Command. Soldiers evaluated the ruck with both the AN/PRC-158 and AN/PRC-162 radios in 'combat-realistic scenarios' to see whether the new setup could prevent damage to radios during parachute jumps. Developers have modified the existing Modular Lightweight Load-carrying Equipment assault pack that's fielded across the service. 'The radio harness allows the radio to be connected to the existing assault frame, while the side pouches allow for individualized space to store antennas away from other equipment and gear,' explained Bob Cohen, Manpack Lead Test Engineer..."

Why Use a Triac?

Why Use a Triac?, April 1974 Popular Electronics - RF CafeThe Triac (triode for alternating current) is not a component often used in RF and microwave circuit design, but being conversant in its operation could make you popular at nerd parties. A triac is basically the equivalent of two SCRs (silicon-controller rectifier, aka thyristor) connected back-to-back, allowing it to conduct on both the positive and negative half-cycles of an AC connection. Both devices are most commonly used in switching applications. The unique feature of an SCR and triac is that once the gate voltage is sufficiently high to begin conduction between the anode and cathode, it can be removed and conduction will continue until the anode-cathode voltage is removed (i.e., holding current removed). This 1974 Popular Electronics magazine article introduces and explains the operation and applications for triacs...

Sora Cinematic AI Generator

Sora Cinimatic AI Generator - RF CafeI, for one, do not fear the emergence of artificial intelligence (AI). The fact is we have been living through an evolutionary process in AI since the beginning of the computer age - it just wasn't called AI at the time. Electronic and mechanical CAD/CAE software with optimization routines are AI. PCB layout autorouting is AI. Weather prediction algorithms are AI. MRI and x-ray images processing is AI, as is tax preparation software. I'd say "get used to it," but you already have. This Sora project by OpenAI (the ChatGPT folks) is basically a real-life rendition version of what Pixar is for cartoon animation. "We're teaching AI to understand and simulate the physical world in motion, with the goal of training models that help people solve problems that require real-world interaction. Sora can generate videos up to a minute long while maintaining visual quality and adherence to the user's prompt. Sora is able to generate complex scenes with multiple characters, specific types of motion, and accurate details of the subject and background. The model understands not only what the user has asked for in the prompt, but also how those things exist in the physical world. The current model has weaknesses. For example, a person might take a bite out of a cookie, but afterward, the cookie may not have a bite mark..." The movie industry is crying foul, but honestly, would many people care if the egotistical, largely ignorant, bloviating Hollywood actors went away?

New Hologram Crystals Permanently Store Images

New Hologram Crystals Permanently Store Images, August 1972 Popular Electronics - RF CafeLithium niobate is used today as the substrate for surface acoustic wave (SAW) filters, oscillators, optical waveguides, and many other applications. It, along with barium niobate, was used experimentally by Radio Corporation of America (RCA) for storing optical images that can be read out later using a laser. This 1972 issue of Popular Electronics magazine included a brief news item referencing the work being done. I could not locate any information that indicates any significant commercialization of the process. Patent US3799642 was awarded in 1974 to RCA Corporation for "Holographic Recording on Photochromic Lithium Niobate." We've come a long way since then with optical data storage, with CDs, DVDs, Blu-rays, and much greater density into the petabit realm...

How to Target RFCafe.com for Your Google Ads

Google AdSense - it makes good sense - RF CafeOne aspect of advertising on the RF Cafe website I have not covered is using Google AdSense. The reason is that I never took the time to explore how - or even whether it is possible - to target a specific website for displaying your banner ads. A couple display opportunities have always been provided for Google Ads to display, but the vast majority of advertising on RF Cafe is done via private advertisers. That is, companies deal with me directly and I handle inserting their banner ads into the html page code that randomly selects and displays them. My advertising scheme is what the industry refers to as a "Tenancy Campaign," whereby a flat price per month is paid regardless of number of impressions or clicks. It is the simplest format and has seemed to work well for many companies. With nearly 4 million pageviews per year for RFCafe.com, the average impression rate per banner ad is about 280k per year (in eight locations on each page, with >17k pages)...

Bell Telephone Laboratories: Electrical Pipe-Line

Bell Telephone Laboratories: Electrical Pipe-Line, July 1946 Popular Mechanics - RF CafeOnce World War II was over, a flood of technical information poured out of government, academic, and corporate research and manufacturing institutions. Making available such data was a promise made by the Department of War to a citizenry which largely supported the wartime effort to maximize resource usage for defeating Axis powers. People and businesses provided raw and recyclable materials as well as services in the interest of assuring our fighting men had every tool at their disposal while fighting for the folks back home. To today's unpatriotic and selfish population it might seem like a Pollyanna and even unlikely view of the world, but that was the case back in the day. Bell Telephone Laboratories (aka Bell Labs) contributed Big League (not "bigly," as ignoramuses claim Trump said) to the pushing forward of technical frontiers. A major development was use of waveguide for microwave systems like radar. As mentioned in this 1947 Popular Mechanics magazine infomercial, their engineers had already figured out how to not only transport radio frequency signals within the confines of waveguide...

Speaking of TVI Issues...

The Severn Bore Tidal Wave: TV Interference - RF CafeHere's a great bit of TVI (television interference) sleuthing for you, as told by RF Cafe visitor Andrew B. "A customer called me with a strange issue, back in the analogue transmission days (UHF). Twice a day at roughly the same time [12 hours apart], BBC channels would completely disappear, only to reappear around 30-45 minutes later. I replaced the antenna, the cable, even the chimney bracket and pole, but nothing fixed the issue. I then arranged with the customer to be on the roof at the time that the issue usually happened. I plugged my meter into the aerial and waited. Sure enough, the SNR shot up and as it did I looked around to see what it could be. Luckily I noticed something from my excellent viewpoint on the ridge next to the chimney! We have a tidal river called the River Severn, and twice a day we get a bore wave as the water rises and recedes. The transmitter was on the other side of this river, around 40 miles away. I then read about how reflections could cause ghosting due to multipathing, and in some cases caused complete loss of desired signal, and how a stacked array could solve these issues. Long story short, using the horizontal stack method, we managed to eliminate the issue completely!"

Mac's Service Shop: TVI from the Victim's Viewpoint

Mac's Service Shop: TVI from the Victim's Viewpoint, March 1972 Popular Electronics - RF CafeWhen I read this installment of Mac's Service Shop, in the March 1972 issue of Popular Electronics magazine, the first thing that came to mind was my own experience with television interference (TVI) when I was a kid. In that case, the transmitter of my radio control system for a model airplane was the culprit. The frequencies and channels are almost exactly the same as reported in this infodrama™. In the 1970s, citizen band (CB) radios operated in the 27 MHz realm, as did my R/C transmitter. During summer vacation from junior high and high school, I would run my model airplanes up and down the street in front of my house, getting up just enough speed to lift off and then immediately chopping the throttle and landing. As soon as the transmitter was switched on, nearby housewives would lean out their doors and yell at me for screwing up "As the World Turns" or "All My Children." They were not particularly happy with noise from the engine, either. I eventually adjusted my operation times to avoid the afternoon soap opera prime time...

"NASA Spinoff" Technology Transfer Program

NASA Technology Transfer Program - RF CafeEver since the manned space exploration programs began at NASA (National Aeronautics and Space Administration), controversy over both the financial costs and the cost in lost opportunity for other government funded programs has existed. Many people, myself included, have always championed the efforts and believe the axiom of the whole being greater than the sum of the parts applies to the efforts. Opponents say resources would be better spent here on Earth. In fact, we have always done both. To address the issue, NASA Spinoff was created to publicize the byproducts of the space program that benefit other areas of research, manufacturing, and society. Since at least the 1970s, NASA has published a monthly magazine entitled NASA Tech Briefs to inform the public on their activities, inviting readers to submit ideas and to request information on how to apply NASA research to commercial applications. I have been a regular reader since around 1980.

withwave microwave devices - RF Cafe

About RF Cafe

Kirt Blattenberger - RF Cafe Webmaster

1996 - 2024


Kirt Blattenberger,


RF Cafe began life in 1996 as "RF Tools" in an AOL screen name web space totaling 2 MB. Its primary purpose was to provide me with ready access to commonly needed formulas and reference material while performing my work as an RF system and circuit design engineer. The World Wide Web (Internet) was largely an unknown entity at the time and bandwidth was a scarce commodity. Dial-up modems blazed along at 14.4 kbps while tying up your telephone line, and a nice lady's voice announced "You've Got Mail" when a new message arrived...

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