Homepage Archive - April 2024 (page 2)

See Page 1 | 2 | 3 | 4 | of the April 2024 homepage archives.

Friday the 12th

The Radio That Was Shot from a Gun

Coming - The Radio That Was Shot from a Gun, March 1948 Popular Science - RF CafeThis article is a good indicator of how prevalent cigarettes were back in 1948 when it appeared in Popular Science magazine. Transmitter, receiver, and hearing air amplifiers were referenced to be "about the size of a pack of cigarettes." The peanut vacuum tubes used within are said to be "smaller than a half-smoked cigarette." Those of us who lived back in the days when smoke-filled restaurants, buses, grocery stores, and houses was the norm easily compare the sizes to such a familiar entity. We even know what it means to be "smaller than a bread box." Nowadays, references to the size of electronic components would be to something like a grain of sand, which is a form of irony since that's what the chip is made from (essentially). The article's title, "The Radio That Was Shot from a Gun," derives from the miniaturization technology developed for anti-aircraft shell proximity fuses...

SmallSat GEO Solution for Satellite Communications

SmallSat GEO Solution for Satellite Communications - RF CafeI wonder if this this is an actually representative of the SmallSat mentioned in the article. It looks like someone Photoshopped a set of PV panels on a standard subsystem module package. "Terran Orbital Corporation has made a significant move into the geosynchronous orbit (GEO) small satellite market with its unveiling of the SmallSat GEO solution, designed for satellites weighing over 500kg. This cutting-edge solution will be showcased at the upcoming SATELLITE 2024 trade show from March 18-21 at the Walter E. Washington Convention Center, Washington D.C., featuring an immersive augmented reality experience. The SmallSat GEO solution is specifically crafted for the communications sector, capable of operating in geosynchronous orbit to deliver unprecedented power and performance, a demand that has surged in the GEO sector's gradual shift towards smaller satellites. Leveraging a state-of-the-art 94,000 sq. ft. manufacturing facility equipped with advanced automation in both construction and testing, along with the experience gained from three prior GEO missions..."

Electromaze Puzzle

Electromaze Puzzle, June 1966 Popular Electronics - RF CafeRobert Radford's (not to be confused with Robert Redford) "Electromaze" is a unique - and weird - sort of word puzzle format which first appeared in the April 1966 issue of Popular Electronics magazine. Some people were confused about the strategy, believing that all the white spaces needed to be filled in. They do not. Just because a letter might have an empty square adjacent to it does not imply that another letter must fill it. You will probably want to print out the maze grid and find an old guy who should still have a pencil stowed away somewhere you can borrow to use for filling in the boxes...

Werbel Teams with Global Electromarketing

Werbel Microwave Teams with Canada's Global Electromarketing - RF CafeWerbel Microwave, located in Whippany, New Jersey, is a producer of high quality passive power RF and microwave components across a worldwide customer base. A partnership has recently been established with Canada's Global Electromarketing, a sales representative agency which focuses on market research, competitive analysis, and brand positioning. Werbel's founder and president Ernest Werbel says, "We are looking forward to growth and success together." Werbel Microwave designs and manufactures RF directional and bidirectional couplers (6 dB to 50 dB) and RF power dividers / combiners (2− to 16−way) with select models operating up to 26.5 GHz and 100 W of CW power (3 kW peak). All are RoHS and REACH compliant and are designed and manufactured in our Whippany, NJ, location. Custom products and private label service available.

Electronics-Themed Comics

Electronics-Themed Comics, January 1951 Radio-Electronics - RF CafeThe January 1951 issue of Radio-Electronics magazine had a big collection of electronics-themed comics - five of them. All of them are pretty good, and you don't need to have been there during the early TV era to appreciate the humor. The comic from page 127 is a good first step in troubleshooting for today, and is usually at the top of the problem solving section of consumer gear throughout the electronic age. The page 126 comic is an oft-used gag for garage-related funnies. Although not directly related, it reminds me of how early wireless garage door openers had their antennas stretched underneath of the car, as mentioned in other articles, including "The New Radio Garage Door Opener."  I colorized them all...

RF & Electronics Symbols for Visio

RF Electronics Wireless Analog Block Diagrams Symbols Shapes for Visio - RF CafeWith more than 1000 custom-built symbols, this has got to be the most comprehensive set of Visio Symbols available for RF, analog, and digital system and schematic drawings! Every object has been built to fit proportionally on the provided A-, B- and C-size drawing page templates (or can use your own). Symbols are provided for equipment racks and test equipment, system block diagrams, conceptual drawings, and schematics. Unlike previous versions, these are NOT Stencils, but instead are all contained on tabbed pages within a single Visio document. That puts everything in front of you in its full glory. Just copy and paste what you need on your drawing...

Thanks to TotalTemp Technologies for Continued Support!

TotalTemp Technologies - RF CafeTotalTemp Technologies has more than 40 years of combined experience providing thermal platforms. Thermal Platforms are available to provide temperatures between −100°C and +200°C for cryogenic cooling, recirculating & circulating coolers, temperature chambers and temperature controllers, thermal range safety controllers, space simulation chambers, hybrid benchtop chambers, custom systems and platforms. Manual and automated configurations for laboratory and production environments. Please contact TotalTemp Technologies today to learn how they can help your project.

Thursday the 11th

Bell Telephone Labs - The Future Holds Great Promise

Bell Telephone Laboratories - The Future Holds Great Promise, August 1949 Popular Science - RF CafeIf you remember watching movies and television shows up through the 1970s or so, you have probably seen scenes (see what I did there?) where someone struggled desperately to place and keep connected telephone calls to, from, or within foreign countries (outside the U.S., that is). Our Bell Telephone Company was well known and respected for the widespread, reliable, and quality network it built out across the land. A continual effort to improve the system while containing costs to make telephony affordable to most people is what did the job. Beginning with manually (or more accurately, womanually) operated switchboards, then graduating to automated electromechanical circuit switching centers, it eventually evolved to the computer controlled and optimized solid state networking circuits of today. Unlike the multitude of telecommunications companies today, Bell really had no competition, so government oversight combined with the company's desire to invoke good will amongst its customers helped keep things in check. Self-promotions like this full-page 1949 Popular Science magazine appearance were common.

Here's One of the Dumbest Statements Ever

Life Without a Smartphone - RF CfeAn article on the TechExplore website entitled, "Why won't some people use a smartphone? And is that difficult?," states, "In a world where more and more services and social interaction are based on mobile apps, a smartphone has become close to a necessity. Despite this, some people avoid smartphones and instead use a dumbphone - a traditional mobile phone or a reduced-feature designer phone." One contributor remarked: "We found that in many societies, all sorts of tricks had to be invented to make life without a smartphone work." Um, does the university prof not realize that life "worked" just fine for the preceding many millennia without a smartphone? Evidently now if you don't feel the need to be "connected" 24/7, you're considered a weirdo. Well, count me in that group. I rarely carry a phone - dumb or smart. I read from and write (even cursive) on paper. I look up definitions and spellings in a printed Webster dictionary. My landline phone sits on the desk and has a handset on a curly cord. I eat meals and do household tasks without checking a phone ...been managing to eek out a survival that way for 65 years now. Other than by tracking purchases on credit cards around town, nobody has a record of my whereabouts or schedule. I pity the phone slaves.

How the Cathode-Ray Tube Works

How the Cathode-Ray Tube Works, February 1955 Popular Electronics - RF CafeEven with the domination of LED, plasma, and LCD displays, there are still cathode ray tubes (CRTs) on the job. Hobbyists workbenches are filled with them for sure, but design and manufacturing facilities still have huge inventories of test equipment with CRTs, and a lot of computer equipment on the production line with CRTs sitting in racks. LED, LCD, and plasma displays all have their own claims to genius on the part of their designers, but cathode ray tube designers - and the designers of the driver circuits - deserve special recognition. Consider the physics and materials involved: glass, phosphor, magnetics, thermonics, electrostatics and electrodynamics, relativity (electrons traveling at relativistic speeds gain mass, requiring stronger deflection fields). This article from the February 1955 edition of Popular Electronics provides a look into the CRT from a layman's perspective...

Exodus AMP2070A, 1−6 GHz, 150 W, SSPA

Exodus AMP2070A, 1−6 GHz, 150 W, 100 W P1dB SSPA - RF CafeExodus Advanced Communications, is a multinational RF communication equipment and engineering service company serving both commercial and government entities and their affiliates worldwide. We are pleased to present the new Exodus AMP2070A solid state high power amplifier, ideal for broadband EMI−Lab, Communication and EW applications. Class A/AB linear design for all modulations & industry standards. Covers 1.0 to 6.0 GHz, producing 150 W minimum Psat, 100 W minimum P1dB, and 52 dB minimum gain, with 20 dB gain adjustment. Excellent flatness, optional monitoring parameters for Forward/Reflected power, VSWR, voltage, current & temperature sensing for superb reliability and ruggedness. Integrated in our compact 3U chassis weighing approximately 25 kg...

How to Use Radio Propagation Predictions

How to Use Radio Propagation Predictions, December 1947 Radio-Craft - RF CafeShort wave radio was a boon to both professional and amateur radio operators because of its ability to be received over longer distances using significantly lower transmitter power. In 1947 when this article appeared in Radio-Craft magazine, the problem was (and still is) that short wave bands typically suffer from atmospheric ionization effects that vary depending on time of day, local weather, solar activity, pollution, and other phenomena. Long wave's advantage was that although it required higher power and longer antennas, it was (and is) extremely reliable. For other than the most critical applications, idiosyncrasies of short wave communications were accepted as the price of more convenient and lower cost operation. Widespread adoption of short wave communications brought extensive studies and characterization of atmospheric influences in particular frequency bands. Discovery of distinct "F" layers (regions) in the ionosphere and their effects on radio transmission has allowed radio operations to predict and accommodate the affected propagation paths. What does the "F" in F-Layer mean? According to my sources the "F" refers not to frequency, but to "free" electrons in the ionosphere...

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...

Wednesday the 10th

U.S. Lights New Atomic Pile for Peace

U.S. Lights New Atomic Pile for Peace, April 1949 Popular Science - RF CafeA Wikipedia on the history of nuclear power shows a photo of the first light bulbs ever lit by electricity generated by nuclear power, at EBR-1 at Argonne National Laboratory-West, December 20, 1951. That was two years after this "U.S. Lights New Atomic Pile for Peace" article in Popular Science magazine, which discusses progress at the Brookhaven National Laboratory, located in New York state. It opened in 1947. Much public excitement - and fear - was fomented over the use of nuclear energy, which had just four years earlier been used to bring an end to World War II through its awesome level of concentrated destructiveness, for peaceful uses like generating electrical power and for medicine. During the postwar era, many such articles, which some considered propaganda, were published, television shows aired, and movies produced in attempts to turn the public into pro- or anti- nuclear power activists. The "anti's" have done a pretty good scaring everyone to the point where rather than benefitting from the very "green" aspects of nuclear power (which would have been continually improving in technology), they instead are accepting monstrous installations of solar arrays, wind turbine farms, and other impractical technologies. Their cost to society, economies, and the environment are rarely reported honestly.

MIT's Dance of Protons

MIT's Dance of Protons - RF Cafe"New insights into how proton-coupled electron transfers occur at an electrode could help researchers design more efficient fuel cells and electrolyzers. A key chemical reaction - in which the movement of protons between the surface of an electrode and an electrolyte drives an electric current - is a critical step in many energy technologies, including fuel cells and the electrolyzers used to produce hydrogen gas. For the first time, MIT chemists have mapped out in detail how these proton-coupled electron transfers happen at an electrode surface. Their results could help researchers design more efficient fuel cells, batteries, or other energy technologies. 'Our advance in this paper was studying and understanding the nature of how these electrons and protons couple at a surface site, which is relevant for catalytic reactions that are important in the context of energy conversion devices or catalytic reactions..."

The Longitude Problem

The Longitude Problem - 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 entitled, 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. Recall your elementary school poem titled In 1942, which began "In fourteen hundred ninety-two, Columbus sailed the ocean blue." John Hadley's and Thomas Godfrey's sextant - originally called an octant - was not invented and refined until the middle of the 18th century. The answer to the first question is that prior to the advent of the sextant and accurate sea-going clocks, determining latitude was easy, but determining longitude was mostly guesswork and dead reckoning...

Moonbats Running Our Lives

Moon is mostly gas - Shiela Jackson Lee - RF CafeMembers of Congress - both the House and the Senate - are not necessarily there because they are exceptionally smart and/or wise. An argument can be made that they are there because their constituents are exceptionally stupid and/or unwise. In an address to students at the Booker T. Washington High School in Houston, Texas, Rep. Sheila Jackson Lee stated, among other dumb things, "the full moon is a complete, rounded circle, which is made up mostly of gasses." She previously claimed the Constitution is more than 400 years old, and that astronauts planted an American flag on Mars (look it up). BTW, she was a member of the House Science, Space and Technology Committee.  Rep. Hank Johnson worried back in 2011 that the island of Guam might tip over under the weight of excessive military gear. Many other examples of idiocy amongst our "leaders" can be found.

RCA "Freedom to Listen"

RCA "Freedom to Listen" Ad, January 1948 Radio-Craft - RF CafeThis RCA (Radio Corporation of America) advertisement from a 1948 issue of Radio−Craft magazine packed a lot of meaning to American citizens who had recently experienced the trials, tribulations, and ultimately victories of World War II. Company president David Sarnoff, a well-known electronic communications industry titan before the war, served under a special commission as a Brigadier General in the U.S. Army during WWII to oversee radio communications. He was very familiar with the tragedy of Communism and Socialism, having experienced its ruinous philosophy. Hitler and his minions forbade citizens, under threat of imprisonment or worse, from listening to radios lest they learn of the war's progress or of the freedoms experienced in other parts of the world. Propaganda via radio was a daunting weapon for and against all engaged nations, and even some Allied governments outlawed both transmitters and receivers for the duration. This advertisement represents the appreciation Mr. Sarnoff and his countrymen had for the simple ability to listen to radio broadcasts without fear of retribution. The scenario depicted in the picture is similar to the famous "Four Freedoms" paintings done by American artist Norman Rockwell in 1943. RCA added "Freedom to Listen" to Rockwell's list for a total of Five Freedoms...

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...

Many Thanks to Amplifier Solutions Corporation for Continued Support!

Amplifier Solutions Corporation (ASC) - RF CafeAmplifier Solutions Corporation (ASC) is a manufacturer of amplifiers for commercial & military markets. ASC designs and manufactures hybrid, surface mount flange, open carrier and connectorized amplifiers for low, medium and high power applications using Gallium Nitride (GaN), Gallium Arsenide (GaAs) and Silicon (Si) transistor technologies. ASC's thick film designs operate in the frequency range of 300 kHz to 6 GHz. ASC offers thin film designs that operate up to 20 GHz. ASC is located in an 8,000 sq.ft. facility in the town of Telford, PA. We offer excellent customer support and take pride in the ability to quickly react to evolving system design requirements.

Tuesday the 9th

Solar Eclipse from Greensboro, NC, April 8, 2024

Solar Eclipse from Greensboro, NC, April 8, 2024 - RF CafeOn April 8, 2024, one of the best total solar eclipses of the last century crossed the United States from Texas to Maine. Because the moon was near its closest orbital point to the Earth, and the Earth was about midway between its orbital apogee and perigee, the sun appeared relatively small and the moon appeared relatively large. That combination caused the moon's shadow to be very wide across the face of the Earth. Note in the NASA eclipse map at the right how much narrower the path of totality was for the August 17, 2017 eclipse. Maximum eclipse for this location was just shy of 81%. That was enough to cause an eerie feel in the sky, but it was nowhere near dark. Let me state that when I first became aware of this solar eclipse, it was sometime around 2016, when I was living in Erie, Pennsylvania. Due to scheduling issues, Melanie and I decided to not travel to South Carolina to view the August 21, 2017 eclipse, figuring we would have a front-row seat to it on April 8, 2024, from our house, which was only a few miles from the center of the path of totality. Life happened, and we ended up moving back to North Carolina in 2022. Because hotel rooms just about anywhere in the path of totality were in the $300+ per night range, we stayed here and missed totality...

Upheaval in Electronics 

Upheaval in Electronics, February 1961 Radio-Electronics - RF Cafe More than half a century has passed since Radio-Electronics magazine editor Hugo Gernsback wrote this piece entitled, "Upheaval in Electronics." In it, he compares the state of the art in electronics since half a century earlier, which would have been 1911 - a couple years before World War I began. He stated the obvious, "Just as electronics of today bears no resemblance to electronics of 50 years ago, the present art cannot be compared to electronics 50 years hence." Of course he was correct. Present day communications routinely goes beyond radio frequencies, into microwave, millimeterwave, nanometerwave (aka light) and onward. As of recent, add to that instantaneous quantum communications over great distances via "entangled" media. Semiconductor technology was relatively new in 1961, with the first monolithic integrated circuit having been developed the year before. As of this writing, Micron has a 5.3 trillion MOSFET memory chip on the market. An entire FM radio receiver, GPS receiver, and radar receiver fits on a single die, sans antenna and power supply - Mr. Gernsback's predicted "diminutive radios." The depth and breadth of modern electronics is impossible to document in a single printed volume. Even the collective works of Wikipedia does not comprise a panoptic resource...

Radio Waves, Sunspots, and Planets

Radio Waves, Sunspots, and Planets, June 1959 Popular Electronics - RF CafeI did a little research on this 1959 Popular Electronics magazine article about John H. Nelson's work on how the positions of planets affect magnetic storms on Earth. It looked a little more like astrology than science, but as it turns out, Nelson's findings gained support in both the astronomical and meteorological fields. Naturally, the astrology crowd claimed him as part of their goofiness, but that wasn't Nelson's fault. He published a book in 1974 titled ,"Cosmic Connections." Yeah, even that sounds like an astrology title - poor choice (or maybe he was trying to fool the contemporary Pharisees in to buying his book). The book is out of print now, and I could not find any contemporary work that leverages Nelson's work. My guess is that due to the relatively short time that observations were made, the sun had not even gone through a full sunspot cycle. Each sunspot cycle, while occurring on average every eleven years or so, can vary widely both in intensity and duration from one period to the next. What might have produced the claimed 85% accuracy for that particular sunspot cycle likely never provided enough correlation in subsequent cycles to solidify the theory...

The Rise and Fall of 3M's Floppy Disk

The Rise and Fall of 3M's Floppy Disk - RF CafeRaise your hand if you used 5¼" floppy disks (360 kB). Raise your other hand if you used 3½" floppy disks (720 kB). Take a bow if you used a cassette tape deck for storing and retrieving programs. I've got both hands raised, and am bowing over. My first external computer storage consisted of a Sears cassette recorder/player connected to a Sinclair ZX80 machine with a membrane keyboard and a 13" color TV for a monitor. That would have been sometime around 1983. According to Wikipedia, in 1976, Shugart Associates introduced the 5¼-inch FDD, and IBM the 3½" in 1986. This IEEE Spectrum article delves into 3M's (Minnesota Mining and Manufacturing) role in the removable storage realm..

Diode Function Quiz

Diode Function Quiz, August 1965 Popular Electronics - RF CafeIt's time for another pop quiz (does that line give you a fearsome flashback to your school days?). Whenever I have one available, I like to post quizzes from vintage electronics magazines, like this one on diode circuit functions which appeared in the August 1965 issue of Popular Electronics. Many from that era include vacuum tubes, but this one has the solid state symbols so the under-40 folks won't be uncomfortable. Your job is to look at the diode circuits and match them with the names of the functions. A couple of them will probably cause some head scratching, but you should do well. Don't jump to a quick conclusion with circuit "E" without noticing the two signal generators attached to it...

RF & Electronics Symbols for Visio

RF Electronics Wireless Analog Block Diagrams Symbols Shapes for Visio - RF CafeWith more than 1000 custom-built symbols, this has got to be the most comprehensive set of Visio Symbols available for RF, analog, and digital system and schematic drawings! Every object has been built to fit proportionally on the provided A-, B- and C-size drawing page templates (or can use your own). Symbols are provided for equipment racks and test equipment, system block diagrams, conceptual drawings, and schematics. Unlike previous versions, these are NOT Stencils, but instead are all contained on tabbed pages within a single Visio document. That puts everything in front of you in its full glory. Just copy and paste what you need on your drawing...

Thanks Again to LadyBug Technologies 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.

Monday the 8th

The Nomorule in Electronic Calculations

The Nomorule in Electronic Calculations, April 1967 Radio-Electronics - RF CafeIn the March 1967 issue of Radio-Electronics magazine, John Fasal introduced his "Nomorule" (a nomograph) as a method of simplifying routine electrical design calculations. In the days prior to smartphones, desktop computers, and electronic calculators, the choices for such figuring were paper and pencil, slide rule, or nomograph - or any combination thereof. The nice thing about a nomograph is the visual presentation of how varying one or more values affects the result. When the equation at hand is linear, the mental work of extrapolating numbers is not so hard, but when exponents, logarithms, or trigonometry functions are involved, things can get tough. Mr. Fasal instructs you on how to generate a custom nomograph for calculating just about any equation. The only restriction is that in general only three scales can be in play at a time - akin to a slide rule - unless other scales happen to fall within the realm of the primary three. Otherwise, if more than three numbers are involved, equations must be constructed that combine two or more quantities, with selected ones fixed at a certain value as a multiplier of the chosen variable. Then, it would be necessary to construct separate scales for each case. For instance, if you needed to calculate the voltage across a resistor that was in parallel with a capacitor and an inductor at various frequencies, you would need to reduce the equation to just three variables and hold one as fixed. That might be the case for a resonant circuit across a resistive load, so if the inductor is fixed in value but the capacitor is adjustable for tuning, an equation would be generated with the L value as a coefficient and f, C, and R as the nomograph scales.

Variable-Voltage Tuning

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

Science Knowledge from April 8th Solar Eclipse

Science Knowledge from April 8th Solar Eclipse - RF Cafe"When a rare total solar eclipse sweeps across North America on April 8, scientists will be able to gather invaluable data on everything from the Sun's atmosphere to strange animal behaviors - and even possible effects on humans. It comes with the Sun near the peak of its 11-year solar cycle, setting the stage for a breathtaking display: The corona will glow spectacularly from the Moon's silhouette along the path of totality, a corridor stretching from Mexico to Canada via the United States. Total solar eclipses offer 'incredible scientific opportunities,' NASA Deputy Administrator Pam Melroy told a press conference this week about the celestial event. The U.S. space agency is one of the institutions at the ready for the eclipse, with plans to launch so-called 'sounding rockets' to study the effects on Earth's upper atmosphere..."

National Solar Observatory Eclipse Map - Data for your location. My area gets a lousy 81%, which won't even cause a noticeable darkening. At 66 years old, this was my last chance to see a total eclipse.

Junction Diode Amplifier, Bell Labs

Junction Diode Amplifier, Bell Telephone Laboratories Ad, November 1958 Radio News - RF CafeRudolf Engelbrecht, an alum of Oregon state University, was inducted into the institution's Engineering Hall of Fame in 1998. As evidenced in this full-page advertisement in a 1958 issue of Radio & TV News magazine, Mr. Engelbrecht's work was instrumental in advancing the state of the art in communications electronics while an engineer at Bell Telephone Laboratories (aka Bell Labs). Here, he is show with the four-stage junction diode amplifier developed for military applications. It exploited the variable capacitance nature of a varactor type diode to effect amplification in the UHF and microwave bands. Engelbrecht went on to work at Radio Corporation of America (RCA) later in his career. BTW, if you are wondering what other kind of diode might there be other than a "junction" diode, the answer is that the earliest semiconductor diodes were "point contact" types which used a sharpened metal wire to make contact with the semiconductor substrate. Of course before that were vacuum tube diodes, but they're not semiconductor-based...

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...

 

 

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