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Oscillator Quiz

Oscillator Quiz, November 1962 Popular Electronics - RF CafeOscillators were never my forte. My biggest exposure to oscillators was unintentional oscillations in amplifier circuits ;-( .  This Oscillator Quiz, published in the November 1962 issue of Popular Electronics magazine, would embarrass me if I attempted to complete it. Therefore, I will simply state that I highly regard your oscillator prowess if you do better than 50% on it. I guessed correctly at a couple of the more familiar circuits, but cannot even make an educated guess at most of them. Don't let the presence of vacuum tubes scare you off; mentally replace them with a FET and move on...

"Sayville Once More"

"Sayville Once More", May 1941 Radio-Craft - RF CafeThese letters represent an unfriendly exchange between The Electrical Experimenter editor Hugo Gernsback and Dr. K.G. Frank, of the Telefunken System of Wireless Technology, of Germany. Gernsback correctly accused Dr. Frank of engaging in espionage for Germany and against the United States of America, during World War I at a time we were not officially at war with the Axis powers. He was arrested and interred for the duration of the war for sending out "unneutral messages" from the broadcast station at Sayville, Long Island, New York. See "Radiobotage" in this month's (September 1941) editorial...

DIY Stratosphere Pico Balloon

DIY Stratosphere Pico Balloon - RF Cafe"There's an interesting development in amateur ballooning: using so-called superpressure balloons, which float high in the atmosphere indefinitely rather than simply going up and up and then popping like a normal weather balloon. Superpressure balloons can last for months and travel long distances, potentially circumnavigating the globe, all the while reporting their position. You might imagine that an undertaking like this would be immensely difficult and cost thousands of dollars. In fact, you can build and launch such a balloon for about the cost of a fancy dinner out. You just have to think small! That's why amateur balloonists call them pico balloons. The payload of a pico balloon is so light..."

Radar Engineering Crossword

Radar Engineering Crossword Puzzle for August 16, 2015 - RF CafeMany of the words in this week's crossword puzzle pertain to radar engineering. All the rest of the words are related to technology, engineering, science, mathematics, aeronautics, ham radio, chemistry, etc. There are no names of Hollywierd actors, shoe designers, or romance novel titles. I will be glad to create a special edition crossword for your newspaper, newsletter, etc. Enjoy...

Mac's Radio Service Shop: Safety in Servicing

Mac's Radio Service Shop: Safety in Servicing, January 1954 Radio & Television News - RF CafeIt's time to gather 'round for another story about fictional radio service shop owner Mac McGregor and his trusted sidekick technician, Barney. In this episode, an errantly wired bypass capacitor on a chassis from one of the old AC/DC radio sets caused Mac to get a 300-volt wakeup call when his hand brushed against it. After explaining the situation to Barney and apprising him of the danger it poses to an owner who unwittingly sticks his/her hand into the back of the cabinet, Mac lists a few other common dangers to watch for. Radios that ran on either AC or DC power were very common back in the early days because there were homes and businesses that had both type systems wired in to the premises - in part due to the famous battle between Thomas Edison's preferred DC electrical distribution system and Nikola Tesla's preferred AC electrical distribution system. Another reason for DC compatibility was that prior to the Rural Electrification Act of 1936, many...

Editorial: Radiobotage

Editorial: Radiobotage, May 1941 Radio-Craft - RF CafeAn incredibly glaring example of the famous admonishment* that those who ignore history are condemned to repeat it, Radio-Craft editor Hugo Gernsback wrote in May of 1941, a full half year before the United States of America officially entered World War II, about how current conditions regarding domestic commercial radio broadcast stations were likely being used by German agents to send coded messages to offshore vessels (ships, submarines, and aircraft). In example, he cited, amazingly, an article he himself published in 1915 in The Electrical Experimenter accusing Dr. K. G. Frank, of the German Telefunken company, of conducting spy operations from the Sayville, NY, station on Long Island...

Crystal Receiver with Transistor Amplifier

A Crystal Receiver with Transistor Amplifier, January 1950 Radio & Television News Article - RF CafeConsidering that not much more than a year before this article was written that the transistor had been invented, it is impressive that already Raytheon was producing a commercially available CK703 "crystal triode." That nomenclature was a natural extension of the preceding crystal diode already being widely adapted in circuit design. If you have wondered how the transistor schematic symbol came to be as it is, you will learn why here where the emitter and collector symbols actually both have arrows on the ends that contact the base, indicating the "point contact" physical arrangement of the semiconductor junctions. Shortly thereafter the arrow on the collector port was eliminated, primarily, I suppose to avoid confusion when the E, B, and C labels are not present...

2D Transistor Transforms Logic, Power Devices

2D Transistor Transforms Logic, Power Devices - RF Cafe"CDimension recently unveiled a technology that enables conventional semiconductor fabs to use ultra-thin semiconductor materials to manufacture vertically integrated arrays of extremely small, fast, and efficient "2D" transistors. It has the potential to change what's possible for both digital and power devices. According to the company, it's already helping several chipmakers explore how to apply their technology to produce digital and analog ICs that offer dramatically higher logic densities, operating speeds, and energy efficiency..."

Radio Service Data Sheets

Emerson Models 20A and 25A Radio Service Data Sheet, July 1933 Radio-Craft - RF CafeHere are three more Radio Service Data Sheets added to the online archive. As mentioned many times in the past, I post these for the benefit of hobbyists looking for information to assist in repairing or restoring vintage communication equipment. These particular radio models - Emerson Model 20A and 25A, Pilot Model B-2, General Electric Model K-40-A - were featured in a 1933 edition of Radio-Craft magazine...

Networks for Television

Networks for Television, November 1947 Radio News - RF CafeNationwide commercial television broadcasting companies wasted no time stringing coaxial cable and microwave towers from sea to shining sea once the NTSC format standard was adopted and manufacturers had spooled up production after World War II. Adoption of cable services was slow because a fee was involved, but once purely cable channels started being added the perceived value increase convinced consumers to open their wallets. Eventually cable eclipsed over-the-air broadcasts for all but extremely rural areas that were not serviced by cable. Along came satellite TV to take care of filling that void. Once a small, inexpensive, unobtrusive Ka-band antenna replaced the huge S-band backyard parabolic dishes and subscription prices dropped significantly, suburbanites and city dwellers picked it up. Soon, cable companies were feeling the pinch as their customer bases shrunk. Not ones to sit...

Oscilloscope Quiz

Oscilloscope Quiz, October 1961 Popular Electronics - RF CafeA lot of RF Cafe visitors might not be familiar with some of the electronic waveforms presented in this Oscilloscope Quiz by Popular Electronics magazine's ultimate quizmaster, Robert Balin. The shapes are recognizable to anyone who has done a lot of design, troubleshooting, testing, or alignments on analog circuits. Electronics repairmen were intimately familiar with these - and much more complex - waveforms. Modulation of the z-axis is especially cool as it varies the intensity of the waveform. I always roll my eyes when, back in the day, a laboratory or medical facility in movies or on TV had an oscilloscope display with a Lissajous pattern writhing on the display...

SpaceX Shifts Focus from Mars to Moon

SpaceX Shifts Focus from Mars to Moon - RF Cafe"SpaceX is putting its longstanding focus of sending humans to Mars on the backburner to prioritize establishing a settlement on the Moon, founder Elon Musk said Sunday. The South Africa-born billionaire's space company has found massive success as a NASA contractor, but critics have for years panned Musk's Mars colonization plans as overambitious. The move also puts Musk in alignment with U.S. President Trump's shift away from Mars. "For those unaware, SpaceX has already shifted focus to building a self-growing city on the Moon, as we can potentially achieve that in less than 10 years, whereas Mars would take 20+ years. Difficulties in reaching Mars include the fact that "it is only possible to travel to Mars when the planets align every 26 months..."

Hands That See: NY Institute for the Blind Prepares Students for Ham License

Hands That See: NY Institute for the Blind Prepares Students for Ham License, December 1947 Radio News - RF CafeLife for the blind has always been fraught with obstacles that we who can see will never be able to fully appreciate. Society has come a long way in accommodating the special needs of those with no or severely reduced eyesight. Recent news stories report of experiments with electronic implants that use implants set into the eye and couple somehow with the retina to send image information to the person's brain. While in no way close to being able to be called sight, it has at least allowed the guy or girl with training to detect and avoid obstacles based on changes in scenery shading. We are probably a century away from true bionic vision, incremental improvements will thankfully improve the lives of our thusly challenged brethren. This article from a 1947 edition of Radio News reports on efforts made by the New York Institute for the Educations of the Blind to make amateur radio...

New! everythingRF Magazine

everythingRF Magazine - RF CafeeverythingRF, a long-time supporter of this website, is now, in addition to publishing e-books, putting out an e-zine which provides some insightful content, interesting products and expert interviews within the RF & Microwave industry. Vol. 4, now available, includes articles on Next Gen Adjustable Q-Band Gain Equalizers, Earth to Orbit:The Important Role of Antennas in NTN, Benefits for Phased Array Systems Through SM Components, as well as product features, upcoming industry events, and more. Download it now.

Mac's Radio Service Shop: Barney Talks A.C.-D.C.

Mac's Radio Service Shop: Barney Talks A.C.-D.C., September 1949 Radio & Television News - RF CafeHave you ever heard of a "globar" resistor? They have been around since the early days of radio and were used, among other things, to protect vacuum tube heater elements from burning up due to high inrush current when first turned on. Globars have a negative temperature coefficient (NTC) of resistance so that, opposite of standard carbon and metal film type resistors, they exhibit a higher resistance when cold than when hot. Mac and Barney discuss their use in this episode of "Mac's Radio Service Shop." You might be more familiar with the name "thermistor" for such devices, but globars are unique elements in that their construction from non-inductive ceramic material makes them useful at high power levels and high frequencies. Globar appears to now be owned by Kanthal (aka Kanthal Globar). Interestingly, Keysight Technologies...

Transistors: Types & Techniques

Transistors: Types & Techniques, November 1962 Popular Electronics - RF CafeLouis Garner was the semiconductor guru for Popular Electronics magazine in the 1960s when he wrote this article attempting to demystify the proliferation of over 2,000 transistor types. He devised a "transistor tree," tracing evolution from the obsolete point-contact transistor - unstable with high gain but noisy - to advanced designs balancing cost, frequency, power, and reliability. It covers pnp and npn basics, then details processes: grown-junction (inexpensive, good high-frequency); meltback diffused (similar, better response); alloyed-junction (popular for power); surface-barrier family (SB, SBDT, MA, MADT; excellent high-frequency, low voltage); post-alloy-diffused...

Notable Quote: Benjamin Peirce

Notable Quote: Benjamin Peirce - RF Cafe"Gentlemen, ei*π + 1 = 0 is surely true, it is absolutely paradoxical; we cannot understand it, and we don't know what it means. But we have proved it, and therefore we know it must be truth." - Benjamin Peirce (not to be confused with Captain Benjamin Franklin "Hawkeye" Pierce), 19th century Harvard mathematician. ei*π + 1 = 0 i, BTW, is known as Euler's identity - engineers live by it.

Twisting Crystal Changes Electricity Flow

Twisting a Crystal at the Nanoscale Changes How Electricity Flows - RF Cafe"Scientists have shown that twisting a crystal at the nanoscale can turn it into a tiny, reversible diode, hinting at a new era of shape-engineered electronics. Researchers at the RIKEN Center for Emergent Matter Science, working with collaborators, have created a new technique for building three-dimensional nanoscale devices directly from single crystals. The approach uses a focused ion beam instrument to precisely carve materials at extremely small scales. Using this method, the team shaped tiny helical structures from a topological magnetic material made of cobalt, tin, and sulfur, known by its chemical formula Co3Sn2S2..."

Hitler Takes up Television

Hitler Takes Up Television, January 1935 Radio-Craft - RF CafeI am constantly amazed when reading stories about how easily Adolph Hitler rose to power in Germany by encouraging and exploiting resentment of his countrymen over being forced, among other concessions outlined in the Treaty of Versailles, to disarm militarily and make reparations for atrocities committed in World War I. Part of the Nazi (National Socialist) party success was extensive use of propaganda via print, radio, and the relatively new technology of television. Government exercised complete control over the mainstream media (i.e., not "underground") by dictating content that promoted the proclaimed virtues of Nazism and the Aryan race and the vices of just about every other form of government and race. At the height of Hitler's reign of terror during the Third Reich era, radio and television sets were only permitted to use crystals tuned to state-sponsored...

More About "Man-Made" Static 

More About "Man-Made" Static, May 1930 Radio-Craft - RF CafeManmade electrical noise (QRM) and natural electrical noise (QRN) has been the nemesis of communications - both wired and wireless - since the first signals were sent. While it is true that over the last century the amount of "background" noise has increased significantly, the ability of modern circuits to deal with (reject) it and/or accommodate (error correction) it has pretty much kept up with the advancement. You might be tempted to think that "back in the good old days" such problems did not exist, but operators were plagued by poorly designed and inadequately filtered transmitters as well as really deficient electrical service installation that spewed noise from transformers, inadequately grounded transmission lines, lousy connections...

Thanks Once Again to everythingRF for Long-Time Support!

everything RF Searchable Database - RF CafePlease take a few moments to visit the everythingRF website to see how they can assist you with your project. everythingRF is a product discovery platform for RF and microwave products and services. They currently have 354,801 products from more than 2478 companies across 485 categories in their database and enable engineers to search for them using their customized parametric search tool. Amplifiers, test equipment, power couplers and dividers, coaxial connectors, waveguide, antennas, filters, mixers, power supplies, and everything else. Please visit everythingRF today to see how they can help you.

Mac's Service Shop: Solid-State Service Instruments

Mac's Service Shop: Solid-State Service Instruments, June 1968 Electronics World - RF CafeThe debate about upgrading electronics service shop equipment from vacuum tube to solid-state instruments was raging in the late 1960s, when this Mac's Service Shop story appeared in Electronics World magazine. Barney is querying Mac regarding FET-based VOM performance specifications he is considering to replace a VTVM. He covets the Hewlett-Packard 217A square-wave generator, delivering clean 1 Hz-10 MHz waves with 5-ns rise time and scope triggering, justifying its $300-$400 cost for precise scope testing. An electronic counter for 5 Hz-10 MHz frequencies, with four- or six-digit readouts and line- or crystal-gated accuracy..

Bell Labs Ad: Test Tube for Sound

Test Tube for Sound Bell Labs Advertisement, December 1947 Radio News - RF CafeA lot of people like to demean engineers and scientists for their propensity to want to conduct experiments and obtain measured, empirical data rather than "winging it" and being satisfied with "intuitive" knowledge or the contemporarily popular term "gut." If mankind had not adopted scientific methods and ventured beyond the "cradle of civilization" on the African continent, we would all still be living in grass huts, hurling rocks at prey, making clicking sounds for communication, and foraging for berries. Quantifying and categorizing all things in nature helps inventors create new and improved implements that help make life better. Early on it was mostly individuals like Archimedes, Euler, Newton, and Edison who built the pool of knowledge that fed and evolved into corporations, governments, and universities doing the vast majority of the work. Bell Laboratories...

Donut-Shaped Light for More Reliable Wireless

Donut-Shaped Light Could Make Wireless Signals Far More Reliable - RF Cafe"A new metasurface lets scientists flip between ultra-stable light vortices, paving the way for tougher, smarter wireless communication. Scientists have developed a new optical device capable of producing two different types of vortex-shaped light patterns: electric and magnetic. These unusual light structures, called skyrmions, are known for their exceptional stability and resistance to interference. Because they hold their shape so reliably, they are strong candidates for carrying information in future wireless communication systems. 'Our device not only generates more than one vortex pattern in free-space-propagating..."

Carl & Jerry: Gold Is Where You Find It

Carl and Jerry: Gold Is Where You Find It, April 1956 Popular Electronics - RF CafeYou can buy a pretty good metal detector today for a hundred dollars that will find coins buried many inches deep and larger metallic items even deeper, and you even get discriminator functions to filter out unwanted objects like tin cans. They weigh just a couple pounds and can be used with one arm. Compare that to early metal detectors that had huge induction coils on a frame so heavy that shoulder straps were needed just to lug them around. Some models came on wheels for pushing or pulling like a cart. You could plan to spend a few hundred dollars (a thousand or more in today's dollars) for one. Even then, they were not as sophisticated as the $50 models sold in Walmart now. In classic fashion, teen electronics hobbyists Carl and Jerry use their technical prowess to design and build their own metal detector and then unintentionally using it to convince...

Technical Headlines - RF Cafe

• Legacy Memory (DDR2, 3, 4) in Demand but Scarce

• 2026 is Year of 6G Slop

• FCC to Exempt Amateurs from Foreign Adversary Reporting

• Continuing Your Professional Education in 2026

• India Reaches 400M 5G Subscribers in 3 Years

• EIB Backs Europe's 1st Gallium Production Investment

Today in Science History - RF Cafe
Homepage Archives - RF Cafe

The RF Cafe Homepage Archive is a comprehensive collection of every item appearing daily on this website since 2008 - and many from earlier years. Many thousands of pages of unique content have been added since then.

Emergency Radio Truck Covers Detroit Area

Emergency Radio Truck Covers Detroit Area, December 1954 Popular Electronics - RF CafeWith such a good response to the posting of articles from vintage QST magazines, I figured it would be worth investing in some copies of other electronics-related magazines because people old and young enjoy learning about the history of electronics. Popular Electronics was published from October 1954 through April 1985. I remember reading the magazine back in my USAF days (1978-1982). A couple batches of Popular Electronics magazines came up for auction on eBay back in the middle of 2011, and I managed to snag one set that included the December 1954 issue (Vol. 1, No. 3, which was the third edition ever printed). It also included some editions from early 1955 and others stretched into the early 1960s. This is the first installment. Popular Electronics was a hobbyist's magazine, and was chock full articles on small electronics projects, Ham radio, radio-controlled aircraft equipment, audio amplifiers, model train control, basic electronics lessons, and useful charts and tables of data...

Radio Training Association of America Advertisement

In God We Trust: All Others Pay Cash - RF CafeWhenever I see advertisements for electronics training courses, I think of the line in "Duel in the Snow, or, Red Ryder Nails the Cleveland Street Kid," where it mentions how during the Great Depression years the magazines were filled with ads "promising successful careers repairing radios." That story, which ultimately became the book and movie "A Christmas Story," was contained in Gene Shepherd's book In God We Trust: All Others Pay Cash. Jean Shepherd was a radio announcer and story teller who first read "A Christmas Story," on his WOR (New York City) show in 1970. You can listen to a 1974 broadcast in the YouTube video embedded below. This reading is slightly different than the one given to me by a guy who actually recorded it on tape...

I.F. Coil & Transformer Design

I.F. Coil & Transformer Design, April 1932 Radio-Craft - RF CafeThe use of intermediate frequency (IF) coils and interstage coupling transformers were a major feature of vacuum tube based receivers. Both served the dual purpose of impedance matching and frequency selectivity. Resistive losses in the relatively large passive components required careful attention to matters that affect signal sensitivity, especially in the front end where losses add significantly to the overall noise figure. This article appeared in an early 1930s edition of Radio-Craft magazine at a time when superheterodyne receivers were just coming into popularity and were a new challenge for many designers because of the variable frequency oscillator...

Mac's Radio Service Shop: Intermittents Still Pursue

Mac's Radio Service Shop: Intermittents Still Pursue, February 1949 Radio & Television News - RF CafeMac McGregor, owner of Mac's Radio Service Shop, can always be counted on to provide his apprentice technician, Barney, with a lesson from his own life-long attendance at the School of Hard Knocks. Barney is your stereotypical young buck whose level of seriousness needs occasional alignment, just as do the radio and television sets he services. In this episode, I can't find where Mac actually solved the intermittent electrical condition believed to be causing the problem - weird. The "Mac's Radio Service Shop" series ran in Radio & Television News magazine for many years prior to a similar electronics story series called "Carl & Jerry" that appeared in Popular Electronics. Both were created by consummate storyteller John T. Frye...

Future Radio Rockets

Future Radio Rockets, April 1944 Radio-Craft - RF CafeWe don't hear much - if any - talk these days about a certain weapon type being a "peace maker," "game changer," or a "stale mate proposition." That is because most nations, or for that matter terrorist groups, have access to some ferocious weapons. The world has operated for a long time on the Mutually Assured Destruction (MAD) principle, where skirmishes have been fairly local. Many conspiratorialists as well as arguably rational people believe the real game at hand is Mutually Assured Financial Destruction (no clever acronym for that one), where world financial powers cooperatively trade off monetary wins and losses via what was termed by President Eisenhower the Military-Industrial Complex. You don't need to be one who wears a tinfoil hat or keeps your savings buried in a jar in the back yard to suspect at least some form of malfeasance is going on at the expense of we the little people...

Smellevision Now Here!

Smellevision Now Here!, June 1951 Radio-Electronics - RF CafeWe all know that for the most part television stinks. Back in 1951 when this article appeared in Radio-Electronics magazine, the technology was very new and it was considered a miracle not to be wasted on inane programming. Newscasts actually presented news and not opinion, movies and sitcoms cast the nuclear family, law enforcement, the military, religion, and patriotism in a positive light rather than as the purveyors of evil in the world. By the end of the 1960s to early 1970s a lot of that had changed. Political and social agendas weaseled their way into nearly all programming to the extent that terms like "boob tube" and even, yes, "smellivision," became common monikers for television. The form of smellivision presented in this article was granted patent (US2540144A) protection in 1951 under the title, Television with scent effects..."

The Capacitor: What It Is, What It Does, How It Works

The Capacitor: What It Is, What It Does, How It Works, April 1960 Popular Electronics - RF CafeHere is a very nice primer on capacitors that appeared in the April 1960 issue of Popular Electronics. A lot of ground is covered including history, form factors, dielectric types (ceramic mentioned as a new variety at the time), applications, etc. Interestingly, units of picofarads (pF) were still being referred to as μμfarads. In fact, since not a lot of work was being done yet in the GHz realm, there was not much use for pF other than maybe to tune a filter response. Author Ken Gilmore reveals a sense of humor when writing of early capacitance experiments as he says, "Since they couldn't think of much to do with the Leyden jar except stand around and shock each other, they didn't have any need for an accurate system of measuring the stored charge, or the capacitance, of the jar."

Electronic Measurement Quiz

Electronic Measurement Quiz, January 1963 Popular Electronics - RF CafeThe early 1960s was evidently a good time for printing quizzes in electronics magazines. Popular Electronics was no exception. As I look through my collection I am finding quite a few. Here is the latest, from the January 1963 edition, that tests basic knowledge of using analog multimeters (digital types were not around yet). All are pretty straightforward; however, be careful with question 9. At first I thought maybe it was a trick question, but the key to arriving at the correct answer is noting that you are measuring a low resistance. Be sure to consider the properties of a standard multimeter of the era. Give it a try for yourself to see how well you fare. There was another Electronic Measurement Quiz in the August 1967 issue of Popular Electronics...

Lafayette Chassis Model B-100 Radio Service Data Sheet

Lafayette Chassis Model B-100 (Table Model B-103; Console Models B-101, B-102) Radio Service Data Sheet, August 1941 Radio-Craft - RF CafeThe Radio Service Data Sheets that were published in Radio-Craft magazine usually seem to have more information included than those published in other magazines, at least in the same era (1940-ish). It might have to do with how much material is provided by the manufacturer rather than a decision by the magazine editors. Either way, here are the schematics, chassis layout, and service info for the Lafayette Model B-100 through B-103. As with most radios built in the era, the woodwork and artistic design of the cabinet are exquisite. There are still people searching for such data, but fortunately the Internet is making it much easier to locate. None of the three models show up on eBay as of this writing...

Anti-Collision Systems for Autos

Anti-Collision Systems for Autos, October 1972 Popular Electronics - RF CafeThis article reporting ongoing research for auto anti-collision systems and backup warning systems appeared in a 1972 issue of Popular Electronics has only come to practical fruition within the last decade and a half. High-end cars were offering such equipment options in the early 2000s, but it has only been commonplace since around 2010. 1972 components were still pretty large and power hungry, and digital processing capacity and speed was significantly less advanced as well. Bendix, one of the early developers of anti-collision systems, estimated that the option on a new car might add about $200 to the price, which was a really ambitious estimate, even considering that is the equivalent of $1,492 in 2024 money per BLS Inflation Calculator. The total add-on cost of both anti-collision and backup warning systems...

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...

A New Arm of the Law

A New Arm of the Law, March 1930 Radio News - RF Cafe"In my judgment, it will be only a few years before all police departments will be equipped with radio," Superintendent A. A. Carroll, Grand Rapids Police Department. Such a statement could have been deemed risky - or even career-ending back in the late 1920 to early 1930s when radio communications was still in its infancy. A lot of public figures denounced radio for anything other than a means of receiving entertainment at home. After all, the equipment was physically large and very power hungry. It was considered folly by many people to believe that an automobile's electrical generation capability would ever be able to power a vacuum tube receiver, much less a transmitter that would have enough range to be useful. Still, police and fire departments forged ahead and became some of the leaders in technology implementation. It was a huge deal in 1930 when a police station installed radios in its fleet of patrol cars, often requiring special fund raising activities or raiding of funds originally set aside for other projects...

RF Cafe Quiz #16: Antennas

RF Cafe Quiz #16: AntennasAll RF Cafe Quizzes make great fodder for employment interviews for technicians or engineers - particularly those who are fresh out of school or are relatively new to the work world. Come to think of it, they would make equally excellent study material for the same persons who are going to be interviewed for a job. The subject of Quiz #16 is Antennas. You don't need to be an antenna expert to score well, but if you do or plan to work with antennas and cannot answer a question like, "What does dBi, the most often used unit for antenna gain (or directivity), stand for?," then maybe it is time for some review...

Sunday 17

Engineering & Science Crossword Puzzle for November 17

Engineering & Science Crossword Puzzle November 17, 2019 - RF Cafe For two decades, I have been creating custom engineering- and science-themed crossword puzzles for the brain-exercising benefit and pleasure of RF Cafe visitors who are fellow cruciverbalists. This November 17, 2019, puzzle uses a database of thousands of words which I have built up over the years and contains only clues and terms associated with engineering, science, physical, astronomy, mathematics, chemistry, etc. You will never find a word taxing your knowledge of a numbnut soap opera star or the name of some obscure village in the Andes mountains. You might, however, encounter the name of a movie star like Hedy Lamarr or a geographical location like Tunguska, Russia, for reasons which...

Engineering & Science Crossword Puzzle for March 31

RF Cafe Engineering & Science Crossword Puzzle March 31, 2019Since 2000, I have been creating custom technology-themed crossword puzzles for the brain-exercising benefit and pleasure of RF Cafe visitors who are fellow cruciverbalists. The jury is out on whether or not this type of mental challenge helps keep your gray matter from atrophying in old age, but it certainly helps maintain your vocabulary and cognitive skills at all ages. A database of thousands of words has been built up over the years and contains only clues and terms associated with engineering, science, physical, astronomy, mathematics, chemistry, etc. You will never find a word taxing your knowledge of a numbnut soap opera star or the name of some obscure village in the Andes mountains. You might, however, encounter the name of a movie star like Hedy Lamarr or...

The Future of Thin-Film Active Devices

The Future of Thin-Film Active Devices, January 24, 1964 Electronics Magazine - RF CafeWhen Charles Feldman published this article on thin-film transistors (TFTs) in a 1964 issue of Electronics magazine, he had no idea that the devices would eventually play a major role in liquid crystal displays (LCDs) in everything from wristwatches to large screen television and computer displays. Materials and fabrication techniques have evolved considerably since 1964, but the fundamentals remain the same. Other than LCDs and some solid-state sensors, I am not familiar with any other applications that are heavy users of TFT technology. This 2016 paper titled, "Review on thin-film transistor technology, its applications, and possible new applications to biological cells," gives a little historical perspective and a comparison of CMOS versus TFT...

Engineering Crossword Puzzle

Engineering Crossword Puzzle, June 21, 2015 - RF CafeFor the sake of avid cruciverbalists amongst us, each week I create a new crossword puzzle that has a theme related to engineering, mathematics, chemistry, physics, and other technical words. You will never be asked the name of a movie star unless he/she was involved in a technical endeavor(e.g., Hedy Lamar). Enjoy...

Last Chance to Buy a New Radio - c1942

Last Chance to Buy a New Radio - c1942 (Kirt's Cogitation #308) - RF CafeIt is probably safe to say that most people, especially today, believe that the United States was suddenly and unexpectedly thrust into involvement in World War II on December 7, 1941, when the Japanese navy launched a surprise attack on Pearl Harbor. The fact is the U.S. was "unofficially" engaged for over a year beforehand by "lending" both equipment and personnel to British, Russian, Chinese, French, and other militaries as part of their effort to drive back invading German, Italian, and Japanese Axis forces. World War II actually began in the Fall of1939 with Hitler's invasion of Poland. Americans, being safely separated from the front lines by the Seven Seas, knew little of and were concerned little about the goings on "Over There." Once the call to arms was sounded with the Pearl Harbor attack, the country quickly and enthusiastically converted to full wartime mode. Manufacturing plants...

Temwell Filters - RF Cafe
EMC Directory Test Equipment & Facilities - RF Cafe



dB Control dB-9006 Magnum Opus Synthesizer - RF Cafe