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Amplifier Solutions Corporation (ASC) - RF Cafe

Werbel 40 dB Dual Directional Coupler for 1-250 MHz

Werbel Microwave 40 dB Dual Directional Coupler for 1 to 250 MHz - RF CafeWerbel Microwave's Model WMHPDDC-1-250M-40dB-N is an internally isolated, dual directional coupler that covers the 1-250 MHz band with 40 dB nominal coupling (±2.5 dB) and high directivity, using N-female RF connectors. Capable of handling 100 watts CW. Coupling flatness ±0.75 dB typical. Mainline loss 0.43 dB typical. Directivity 33 dB typical. Return loss mainline 30 dB typical. Isolation is 73 dB typical. Operating temperature is -10 to +65°C. Purchase direct via DigiKey Marketplace...

Too-Small Cubicles: 1932 "The Wireless World" Article 

Broadcast Brevities, March 9th, 1932 The Wireless World Article - RF CafeAs the old saying goes, "The more things change, the more things stay the same." Incredibly, back in 1931 people were complaining about shrinking office cubicle sizes. To wit: "At 'Broadcasting House' rooms measuring 8ft. x 6ft. are being coveted by the many people who will be condemned to labour in cubicles 7ft. x 5ft. The Civil Engineer himself, who helped to design and erect the building, works in a compartment in which, as the American said, 'You couldn't cuss a cat without getting hair on your teeth.'" ...and whoa!, dig this statement by the author regarding the demise of "local oscillators" in the UK (noisy regenerative Rx LO interference): "Steps might be taken to ensure the survival of a few specimens, perhaps by the founding of a national reservation similar to those which accommodate the Red Indians in America. The few remaining squealers and their..."

Panoramic Reception

Panoramic Reception, March 1945 QST - RF Cafe"Technically, panoramic reception is defined as the simultaneous visual reception of a multiplicity of radio signals over a broad band of frequencies. In addition, panoramic reception provides an indication of the frequency, type and strength of signals picked up by the receiver. Deflections or 'peaks' appearing as inverted 'V's on the screen of a cathode-ray tube." It is the kind of display that radar operators at Pearl Harbor were using when they mistook wave of incoming Japanese bombers a squadron of B-17s from the mainland. The panoramic receiver is not a wartime development, experimental models having been produced just prior to the outbreak of war. However, the many uses to which it has been put have demonstrated that the panoramic idea, particularly in the form of adaptors which may be connected to any receiver, is going to be very important...

Antenna Placement Does Make a Difference!

Antenna Placement Does Make a Difference!, November 1966 Popular Electronics - RF CafeThis article in a 1966 issue of Popular Electronics presents a surprising and almost counterintuitive result when measuring the radiation pattern of a CB-type antenna mounted at various points on a car. If you were asked to make a rough sketch of the radiation pattern when the antenna is mounted in the center of the roof, center of the trunk, and on each of the front and rear and left and right fenders, would yours look like those in the article (assuming an all-metal car)? Today, there are many electromagnetic radiation pattern simulators available to help predict antenna performance in just about any scenario imaginable. Design verification is then usually performed either in actual operational conditions, in anechoic chambers, in TEM cells, or on outdoor test sites. Being able to accomplish the initial simulation using software algorithms...

The Real Inventor of Wireless

The Real Inventor of Wireless, October 1965 Popular Electronics - RF CafeCredit for being the first to accomplish any notable feat, whether in sports, medicine, science, aviation, etc., is constantly being challenged. Some contestations are worthy of consideration based on documented facts, while others can be readily dismissed as crockery. Gustave Whitehead, per anti-Wright Brothers zealots, made the first powered airplane flight. The Vikings landed in America centuries prior to Columbus - supposedly. Many stories have been written claiming that Dr. Mahlon Loomis, a dentist, beat Guglielmo Marconi in the wireless communications race by using a system of kites that took on a charge from overhead clouds. A keying device opened and closed a conductive path to ground for effecting the Morse code...

Self-Assessment of "The Peril of AI-Generated Misinformation"

Self-Assessment of "The Peril of AI-Generated Misinformation: A Self-Flagellating," Kirt's Cogitation #372 - RF CafeA few days ago I posted a piece entitled, "The Peril of AI-Generated Misinformation: A Self-Flagellating Treatise on the Erosion of Truth," where I instructed four AI engines to create an article describing the potential damage that could be wreaked by creating and/or perpetuating false or misleading information. I call it a Lenin-esque result from "If a lie is told often enough, it becomes the truth." We witness that tactic committed by human media apparatchiks all the time. Search engines - even unbiased ones - tend to return results based on a majority opinion of online content. Many YouTube videos show a montage of news anchors on unaffiliated outlets reciting a script which much have been mass distributed in order that broadcast transcripts posted online from multiple popular sources contain identical or near-identical text. I asked the AI engines to perform a self-assessment of its own writing in the previous exercise to search for any errors it might have created and/or perpetuated...

Using Silicon Diodes

Using Silicon Diodes, July 1965 Popular Electronics - RF CafeI like the opening line to this 1965 article on using silicon diodes, "You can stack' em up to get all the power supply voltage you need, but you have to know how to dress 'em up." The basic rules of solid state diode implementation have not changed much since they first began gaining widespread usage. Observing peak inverse voltage (PIV), forward and leakage current, and power dissipation rating limits were and still are the primary concerns for diodes. Moving to higher frequencies, particularly in communications applications, requires attention to junction capacitance, self-generated noise, and forward and reverse recovery times. Physical size and ruggedness, temperature and humidity, and even shielding from cosmic rays can also need careful consideration...

Many Thanks to Anatech Electronics for Long-Time Support!

Anatech Electronics logo - RF CafeAnatech Electronics (AEI) manufactures and supplies RF and microwave filters for military and commercial communication systems, providing standard LP, HP, BP, BS, notch, diplexer, and custom RF filters, and RF products. Standard RF filter and cable assembly products are published in our website database for ease of procurement. Custom RF filters designs are used when a standard cannot be found, or the requirements dictate a custom approach for your military and commercial communications needs. Sam Benzacar's monthly newsletters address contemporary wireless subjects. Please visit Anatech today to see how they can help your project succeed. 

Comics with an Electronics Theme

Comics with an Electronics Theme, March 1965 Popular Electronics - RF CafeTGIF, and that means tech-themed comics from vintage electronics magazines if I happen to have any. You'll really appreciate the comic on page 96 of the 1965 issue of Popular Electronics magazine. In a way, the drawing's concept was very prescient regarding the future of flexible, bendable circuits. A big part of the electronics world at the time centered around servicing all the newfangled circuits and test equipment for troubleshooting and aligning them. As is still true today, technology changed quickly and there was always a newer model television, radio, tape recorder, stereo system, video recorder, etc. Customer interactions and repair shop experiences provided plenty of amusing fodder for magazine articles and comics. I took the liberty of coloring them...

Facts About Lightning Protection

Facts About Lightning Protection, July 1959 Electronics World - RF CafeLightning season is upon us once again. The National Weather Service says June, July, and August, are the most active lightning months in the U.S., which is probably true in all of the northern hemisphere, and then December, January, and February in the southern hemisphere. According to the National Safety Council, the average American has a 1:114,195 chance of being killed by lightning in a lifetime (which ends abruptly upon being killed). That's much less than your chance of dying due to cancer (1:7) or being killed in a car accident (1:102), but is sucks if you're that one in 114,195. Not all lightning strikes are fatal, but many cause personal and property damage. Mitigating the chance of being harmed requires taking some simple actions to not expose...

Engineering & Tech Headlines <Archives>

• FCC Accuses EU Regulators of Harbouring Anti-American Biases

• GlobalFoundries Pledges $16B U.S. Investment

• Wireless Providers Dominating Broadband

• Q1 Mobile Core Market up 32% YoY

• Supply Chain Must Confront Divergence

Anritsu to Demonstrates Key Non-Terrestrial Network

Anritsu Collaborates with Industry Leaders to Demonstrate Key Non-Terrestrial Network Use Cases - RF Cafe"Anritsu Corporation announces its participation as a Test and Measurement partner in two pioneering demonstrations of 3GPP Rel-17 compliant Non-Terrestrial Network (NTN) technology at the 2025 5GAA meetings in Paris. The demonstrations provided the first of their kind measurements showcasing the readiness of the technology and ecosystem to revolutionize automotive safety. In one of the collaborations with industry leaders BMW Group, Deutsche Telekom, Viasat and Skylo, Anritsu contributed to successful measurements of end-to-end NTN Key Performance Indicators (KPIs)..."

Amateur 2-Meter FM Repeaters

Amateur 2-Meter FM Repeaters, May 1973 Popular Electronics - RF CafePrior to the advent of earth-orbiting satellites, very long range communications like between continents was dependent on the state of the various ionosphere levels. There is never a completely predictable "open" channel from point A to point B. A satellite repeater, however, while not always in a position to be within view of both points, at least is predictable based on a published ephemeris of times and positions. The first OSCAR (Orbiting Satellite Carrying Amateur Radio), now governed by AMSAT, was launched in December of 1961. This 1973 article in Popular Electronics mentions OSCAR 6, which was launched in October 1972...

Electronics Metals Quiz

Electronics Metals Quiz, October 1964 Popular Electronics - RF CafeThis Electronics Metals Quiz appeared in the October 1964 edition of Popular Electronics. Given the era and obsolescence of some technologies, a couple of the drawings might not be recognizable to you. Accordingly, I feel obligated to clue you in on those. "B" is a television iconoscope, which was used in early TV video cameras. "D" is a phonograph stylus. For "F," keep in mind the prevailing semiconductor material at the time. "I" is a type of heater element that could be screwed into a light bulb socket (I used to have a couple). "J" is supposed to be a needle for a meter movement. Now that you know, have at it. The process of elimination should result in a good score. I got 10:10, but then I'm older than the quiz...

A Bonus for CATV Subscribers: Cable FM

A Bonus for CATV Subscribers: Cable FM, January 1971 Popular Electronics - RF CafeAccording to a plethora of news reports in the last few years, the "cord cutting" phenomenon is having a significant impact on cable media providers. Consumers long ago grew tired of the monopolistic practices of corporations forcing mostly unwanted programming onto everyone and then trying to convince them that they were getting a good deal if the cost per channel was considered. No one bought that argument, but it didn't matter because there was no competition for service. Public Utility Commission (PUC) efforts to force prime line owners to rent out "space" in an attempt to provide competitive products has never worked, but that doesn't keep PUCs from trying (job security). The advent of wideband wireless service has opened up a new realm of media delivery that is leaving wired service in the dust. Not only is cellphone...

Trump Mobile Launches w/Golden Phone

Trump Mobile Launches w/Golden Phone - RF Cafe"Trump Mobile launches as a new mobile service and will also sell its own mobile device, the T1, offering an 'all-American service for our nation's hardest-working people.' 'Alongside the team from Trump Mobile, Donald Trump Jr. and Eric Trump unveil T1 Mobile, a transformational, new cellular service designed to deliver top-tier connectivity, unbeatable value and all-American service for our nation's hardest-working people,' opens a post on the Trump Organisation website. Trump Mobile claims to be a next-generation wireless provider.' It offers 5G service through all three major cellular carriers, presumably meaning T-Mobile, AT&T and Verizon, and it is holding up The 47 Plan as a flagship package which goes for $47.45 per month..."

Anxiety Amid Affluence: Why Color-TV Makers Worry

Anxiety Amid Affluence: Why Color-TV Makers Worry, December 27, 1965 Electronics Magazine - RF CafeDecisions, decisions, decisions. As the title states, color television manufacturers were, in 1965, finding themselves between a rock and a hard place, as the saying goes, regarding a change from vacuum tubes to transistors. The buying public (aka consumers) had mixed emotions about the newfangled semiconductors based at least partly on bad information about transistors. Transistors had been designed in various circuits for a decade and a half and were gaining rapidly in performance and reliability. The price was coming down, but as reported here, still cost $5 to $10 apiece compared to a $1 vacuum tube. Company management needed to decide whether to delay implementing the new engineering and production methods required to deal with transistors for a couple more years until the market had more time to make up its mind whether to begin. A couple firms enthusiastically...

Hams in Combat: A Lady of Mercy

Hams in Combat: A Lady of Mercy, July 1944 QST - RF CafeThis is another installment of the "Hams in Combat" series that the ARRL's QST magazine ran during WWII. I enjoy vicariously waxing nostalgic of a time before I was born, at time when there was still honor, courage, selflessness, and pride of country. During World War II, it was an ingrained part of most citizens, whether or not they happened to be serving in the military. Our modern day troops still have it, but sadly fewer and fewer people see their own country as any place special in the world. Many don't believe it ever was. Sure, as General William Tecumseh Sherman famously said, "War is hell," but then again so is witnessing the tearing apart of your country from forces within...

Today in Science History

Today in Science History - RF Cafe

Negative Feedback Transistor Amplifiers

Negative Feedback Transistor Amplifiers, May 1957 Radio & TV News - RF CafeThe big graphic with Figures 1 through 17 reminds me of the kinds of study sheets I used to make when cramming for exams in my college circuits courses. Did I ever tell you about the wise guy instructor I had for my first Circuits class at the University of Vermont? Anyway, this article provides an introductory level treatment of using negative feedback in amplifier circuits. Lots of illustration and formulas are included. Frequencies are at baseband, so you won't learn any secrets for high frequency amplifier stabilization, but then even RF and microwave circuits eventually need to convert down to baseband at some point for sampling or for use as audio or video...

Special Information on Radio, TV, Radar and Nucleonics

After Class: Special Information on Radio, TV, Radar and Nucleonics, November 1957 Popular Electronics - RF CafeBy 1957, betatrons, cyclotrons, cosmotrons, synchrocyclotron, bevatrons, and other forms of "trons" had the physics world all agog with anticipation of the next big discovery. Quarks were still a decade away from being discovered and something as exotic as the Higgs boson (aka god particle) hadn't entered anyone's mind. The news media was agog with reports of the world possibly coming to the end as a result of those experiments sparking a nuclear reaction chain that would cause the whole world to explode. Today, the news media is no smarter, because nowadays they fret over the Large Hadron Collider (LHC) generating a black hole that will implode the whole world ...

Radio Data Sheet 346 General Electric Farm Radio Model 280 

Radio Data Sheet 346 General Electric Farm Radio Model 280, May 1947 Radio-Craft - RF CafeFor many years, I have been scanning and posting schematics & parts lists like this one that appeared in radio and electronics magazines in the middle of the last century. Most use vacuum tubes. This General Electric Model 280 Farm Radio "Radio Data Sheet" was in the May 1947 issue of Radio-Craft. The Radio Museum website has more information on the GE Model 280 Farm Radio. Farm radios were designed to work on storage batteries since until the Rural Electrification Act of 1936 was put into effect, most rural properties had no commercial AC electric power service. 11 years later, work was in progress to light up the entire country, but many locations had to wait while resources went to service war production needs. No actual example of the Farm Radio could be found online. There are still many people who restore and service these vintage radios...

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...

Practical Techniques of Square-Wave Testing

Practical Techniques of Square-Wave Testing, July 1957 Radio & TV News - RF CafeIf you work with oscilloscopes on a regular basis, you know know one of the first things you do (or should do) is to calibrate the frequency response of the probe by hooking it onto the squarewave port and tweaking the probe capacitor for no overshooting or undershooting at the waveform edges, and then verify that the displayed amplitude is correct. I remember being amazed during engineering courses at learning that any periodic waveform can be described mathematically as the sum of sinewaves at various frequencies, amplitudes, and phases. Knowing the theory behind those waveforms - particularly standard ones like squarewaves, trianglewaves, sawtooths, etc. - really helps in understanding what you see on the o-scope and in troubleshooting problems. The same goes for interpreting the impulse and step function responses as influenced by resistance, capacitance, and inductance effects. Perhaps the most amazing thing I learned about squarewaves is that, based on the Gibbs phenomenon, anything short of an infinite series of additive sinewaves when representing a squarewave results in an overshoot - albeit vanishingly minute - at the edge. In the real world, complex reactive/resistive effects render the effect undetectable...

Men Who Have Made Radio: Count Georg von Arco

Men Who Have Made Radio: Count Georg von Arco, October 1930 Radio-Craft - RF CafeThe persona of Scott Adams' 'Dilbert' is described exactly in the opening sentence of this article in a 1930 edition of Radio-Craft magazine. It is amazing - if not frustrating - to realize how long the perception of science-minded people being introverts has been around. Dilbert's 'pointy-haired-boss' is nailed in the second sentence. Georg Wilhelm Alexander Hans Graf von Arco is celebrated here as a major contributor to the advancement of early radio, particularly wireless telegraphy equipment development. Interestingly, as brought to my attention by Melanie as she did the text clean-up after OCRing the magazine page, von Arco worked at the Sayville radio transmission station on Long Island, New York, where the Telefunken Company's Dr. K.G. Frank was arrested and interred for the duration of the World War I for sending out "unneutral messages..."

Field-Effect Transistors

Field-Effect Transistors, October 1966 QST - RF CafeThe concept of a field effect transistor (FET) has been around in theory for a long time*, but manufacturable devices arrived in designers' labs not until the early 1960s. This article from the October 1966 edition of QST magazine gives a good introduction to the physics of a basic FET as well as the junction FET (JFET) and the insulated gate FET (IGFET), all of which are still in widespread use today. What you learn about them here is applicable today. In fact, I swear some of the drawings are the same ones that appeared in my college semiconductor physics text books (admittedly from the late 1980s, so not too much of a surprise)...

Log Polar Plane Stencil c1958

Log Polar Plane Stencil c1958 - RF Cafe SmorgasbordCanadian website visitor Richard F. sent me this photo of his "Log Polar Plane" acetate stencil, circa 1958. As a collector of vintage of science / technical paraphernalia, he ran across this as part of one of his acquisitions. "Computing Aids" is printed on it. I had never heard of the log polar plane, but according to the Wikipedia entry, "In mathematics, log-polar coordinates (or logarithmic polar coordinates) is a coordinate system in two dimensions, where a point is identified by two numbers, one for the logarithm of the distance to a certain point, and one for an angle. Log-polar coordinates are closely connected to polar coordinates, which are usually used to describe domains in the plane with some sort of rotational symmetry. In areas like harmonic and complex analysis, the log-polar coordinates are more canonical than polar coordinates." The David Young, on the University of Edinburgh website, explains, "Log-polar sampling is a spatially-variant image representation..."

Electronics-Themed Comics

Electronics-Themed Comics 1958 Radio-Electronics - RF CafeBeing a great appreciator of good humor, and especially technology-related humor, I made sure to scan these electronics-related comics from the pages of vintage Radio-Electronics magazines. You might have to have lived through the era of televisions with cathode ray tubes (CRTs) to fully appreciate the frustration of trying to acceptably grab, align, define, sharpen, tone, and lock an over-the-air broadcast signal on track. Stories of people putting feet or baseball bats through the sets were a big source of situational humor.

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 225,000 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...

Homepage Archives for June 2024

Homepage Archives for June - RF CafeHomepage Archives for June 2024. Items on the RF Cafe homepage come and go at a pretty fast rate. In order to facilitate fast page loading, I keep the size reasonable - under a megabyte (ebay, Amazon, NY Times, etc., are multiple megabytes). New items are added at the top of the content area, and within a few days they shift off the bottom. If you recall seeing something on the homepage but now it is gone, fret not because many years I have maintained Homepage Archives.

Flat Earthers

Flat Earthers - RF CafeOur president and other pontificating politicians - particularly, it seems, those who hold college degrees in non-science realms - have recently taken to referring to anyone who does not hold their points of view as "Flat Earthers" and anti-science. BTW, these are the same people who regularly chastise their opponents for name-calling and uncivil discourse. So, if to them others are anti-science, then they obviously deem themselves to be pro-science. Would you consider a person who laments the invention of the ATM machine because it replaces bank tellers or a ticket kiosk at the airport for robbing counter clerks pro- or anti-science? What about people who prefer to cripple society with a blinders-on approach to energy production by insisting on using "renewable" sources while ignoring advances in fossil and nuclear power sources? Excuse me for getting all sciency[sic] on them...

Engineering & Science Crossword Puzzle for September 29

Engineering & Science Crossword Puzzle September 29, 2019 - RF CafeFor 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. 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. This September 29, 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 ...

Short Waves of Tomorrow

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

Magnetism - Its History

Magnetism - Its History, Basic Navy Training Courses, NAVPERS 10622, Chapter 11 - RF CafeIn the light of recent urgent news about an unexplained, sudden uptick in the migration rate of Earth's magnetic field, this chapter on magnetism from the U.S. Navy's training course is especially interesting. Figure 83 is a snapshot of the magnetic variation (aka declination) isogonic lines as they were around 1945, when this manual was published. I say "snapshot" because those lines are constantly changing. Magnetic declination (variation) is the difference between magnetic north (or south) pole as indicated by a magnetic compass, and the true geographic north (or south) pole around which the earth rotates. Magnetism records locked up in rocks and plants, combined with records kept by ancient mariners who compared compass readings with those obtained from sextants provide the data. As you can see in the animation posted on Wikipedia, the magnetic declination changes significantly. The advent of satellite-based navigation...

Electronic Current Quiz

Electronic Current Quiz, October 1963 Popular Electronics - RF CafeThis Electronics Current Quiz from the October 1963 edition of Popular Electronics magazine is recent enough (if you consider more than half a century ago to be recent) that it uses both transistors as well as vacuum tubes in the example circuits. I have to admit to only scoring 60% on the quiz, which is pretty lame. You will probably do better, especially if you are my age or older. I thought the names of the current type would make the challenge a breeze, but not so in my case. Just as back in school days when looking up the solution to problems in the back of the textbook and the answers seem obvious (well, not always), so, too, do these...

Amplifier Solutions Corporation (ASC) - RF Cafe