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Today in Science History

The Bridged-T

"The Bridged-T Filter, February 1964 Radio-Electronics - RF CafeThe bridged-T filter is a quick-and-dirty construct used to notch out a specific frequency that is interfering with a desirable frequency or band of frequencies. It is a resonant LC (inductor-capacitor) circuit consisting of a single inductor "bridging" a pair of series capacitors having a resistor to ground between them, or, if preferred, a capacitor bridging one or two inductors. A convenient nomogram (aka nomograph) is provided by the author in this 1964 Radio-Electronics magazine article for quickly selecting values, which was a very popular design aid in the pre-calculator era. A slide rule could be used to calculate a range of values when only a single variable was in play, but juggling more than one variable (component value) was greatly aided by a multivariable nomograph. Truth is nomographs can still...

Carl & Jerry: TV Picture

Carl & Jerry: TV Picture, June 1955 Popular Electronics - RF CafeTelevision, in 1955, was still a relatively new phenomenon to many - maybe even most - people. According to multiple sources, the portion of American households with a TV set went from under 20% in 1950 to nearly 90% ten years later in 1960. That was a meteoric rise, particularly considering the expense of even a minimal TV. The technology was not even available commercially when most people were born, so the rush to join in on the craze was akin to the mass adoption of cellphones in the 1990s. "Carl & Jerry" creator John Frye used his pair of electronics-savvy teenagers to help make the "magic" behind recreating a moving picture on a CRT miles away from where it was created. Water flowing through a garden hose has often been employed as an analogy for current flowing through a wire to explain electricity to laymen and beginning students of the craft. Here, it is not water flowing through the hose but water leaving the hose and flowing through the air that serves to represent an electron stream travelling from the electron gun to the phosphor-coated glass front of a CRT. Frame rates, scan lines, deflection coils, and other relevant terms are i

RF Front-End Tech Drives Automotive Innovation

RF Front-End Tech Drives Automotive Innovation - RF Cafe"The RF front-end (RFFE) industry, valued at $21 billion, is expanding beyond its traditional focus on mobile and infrastructure to drive innovation in the automotive sector. Each segment within the industry presents unique dynamics and growth opportunities. After a difficult 2022, the smartphone market is showing signs of recovery, with expected year-over-year growth of 4%, projected to reach 1.2 billion units by 2024. The mobile RFFE market is predicted to hit US$18 billion by the end of 2024, though it may face stagnation due to market saturation and pricing pressures. This market is expected to expand, with the 2027 launch of RedCap..."

Magnetoresistance: Better Than Hall-Effect Multipliers

Magnetoresistance: Better than Hall-Effect Multipliers, April 6, 1964 Electronics Magazine - RF CafeI'm having a hard time writing this with my eyes rolled back in my head. The last time I experienced this level of overwhelmedness was probably the third or fourth week of my feedback and control class at UVM. Even though electricity and magnetism shares many complimentary and parallel concepts, for some reason thinking in terms of magnetics when describing amplifiers, mixers, modulators, etc., has always caused brain freeze. Maybe it has to do with an ingrained bias due to my earliest dealings with circuits being from a technician background before earning an engineering degree. The equations of electric fields and magnetic fields are very similar so that helps lower...

Thanks to Temwell for Their Support!

Temwell (filters) - RF CafeTemwell is a manufacturer of 5G wireless communications filters for aerospace, satellite communication, AIoT, 5G networking, IoV, drone, mining transmission, IoT, medical, military, laboratory, transportation, energy, broadcasting (CATV), and etc. An RF helical bandpass specialist since 1994, we have posted >5,000 completed spec sheets online for all kinds of RF filters including helical, cavity, LC, and SMD. Standard highpass, lowpass, bandpass, and bandstop, as well as duplexer/diplexer, multiplexer. Also RF combiners, splitters, power dividers, attenuators, circulators, couplers, PA, LNA, and obsolete coil & inductor solutions.

What's Your EQ?

What's Your EQ?, February 1962 Radio-Electronics - RF Cafe Here we are with another set of three "What's Your EQ?" circuit challenges, these from the February 1962 issue of Radio-Electronics magazine. As usual, those challenges provided by Jack Darr are the purview of television servicemen of the era. The photo shown of the problematic CRT display looks like a chest x-ray or maybe hieroglyphics in the dark corner of a cave, but evidently the artifacts are readily identifiable to an initiated few. The Forbidden Current Path circuit answer is not what I thought it would be. I maintain that whether my answer or the designer's answer is correct depends on the physical...

New Wireless Data Rate Record Set

New Wireless Data Rate Record Set - RF Cafe"A new world record in wireless transmission, promising faster and more reliable wireless communications, has been set by researchers from UCL. The team successfully sent data over the air at a speed of 938 Gb/s over a record frequency range of 5–150 GHz. This speed is up to 9,380 times faster than the best average 5G download speed in the UK, which is currently 100 Mb/s or over. The total bandwidth of 145 GHz is more than five times higher than the previous wireless transmission world record. Typically, wireless networks transmit information using radio waves over a narrow range of frequencies..."

Sputnik: A Brief History

Sputnik: A Brief History - RF CafeSputnik refers to the first series of satellites launched by the Soviet Union. The word "Sputnik" means "satellite" in Russian. The launch of Sputnik 1 on October 4, 1957, marked a monumental moment in human history, heralding the dawn of the Space Age and sparking a fierce technological competition known as the Space Race between the United States and the Soviet Union. This satellite, the world's first artificial one, orbited Earth at an altitude of roughly 215 to 939 kilometers and broadcast a radio signal that astonished the world, particularly in the United States, where it spurred rapid advancements in aerospace and scientific research. The successful launch of Sputnik was an achievement that was years in the making, involving a combination of visionary planning, political motives, and intensive engineering by some of the Soviet Union's top scientists.

Blog: Air Quality Measurements with Particle Counters

Axiom Test Equipment Blog: Provide Essential Air Quality Measurements with These Particle Counters - RF CafeTranscat | Axiom Test Equipment, an electronic test equipment rental and sales company has published a new blog post entitled "Provide Essential Air Quality Measurements with These Particle Counters" that covers how particle counters can provide essential measurement capabilities that can help avoid contamination and support high manufacturing yields. These measurement tools can detect and measure microscopic particles suspended in air that can contaminate the most carefully planned manufacturing lines. Air particle counters can be designed for various...

Receiving U.S. Satellite Signals

Receiving U.S. Satellite Signals, March 1958 Radio News - RF CafeIn 1958, most people were not accustomed to seeing the now-familiar maps plotting sinusoidal courses of satellites across the face of the earth. It had only been in October of the previous year that any object other than the moon was in orbit around our home planet - that was U.S.S.R.'s Sputnik. Just as people of all ages and all backgrounds enthusiastically joined in the newfangled phenomenon of aeroplanes after the Wright Brothers flew their fragile craft at Kitty Hawk, electronics communications and scientists worldwide hopped aboard the satellite train. This article from a 1958 issue of Radio & TV News magazine provided insight into the construction and flight characteristics...

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.

Radio and Television News - Predictions

Radio and Television News, January 1969 Electronics World - RF CafeWhat were some of the top issues of the radio and television industry half a century ago? In a lot of respects, the same things that concern it today. A ready supply of service technicians was a concern that was taken seriously by the Electronics Industry Association (EIA). While there are not many local repair shops for electronics products nowadays, there is still a huge demand to techs who are willing and able to do the hard work of keeping the world's communication infrastructure operational - climbing towers, repairing cell equipment. Now, as then, good pay, job security, benefits, and respect for the job being done were at the top of...

RIGOL Introduces Oscilloscope & Generator Lines

Impressive Performance at an Impressive Price: RIGOL Introduces Oscilloscope & Generator Lines - RF CafeIn a parallel to the traditional test setup of signal generation and signal acquisition, RIGOL Technologies announced today the latest additions to its portfolio of performance measurement equipment with the introduction of the DG5000 Pro Series Generators and DHO/MHO5000 Series Oscilloscopes. The DHO/MHO5000 Series bring next-level performance to RIGOL's respected line of high-resolution oscilloscopes, while the DG5000 Pro generators do the same for the company's capable Pro Series arbitrary waveform generators...

Basic Electronic Counting

Basic Electronic Counting, March 1958 Radio News - RF CafeWhen selecting articles for posting here on RF Cafe, I like to include ones that are directed toward newcomers to the field of electronics as well as for seasoned veterans. This piece from a 1958 issue of Radio & TV News magazine entitled "Basic Electronic Counting," is a prime example in that it introduces the concept of binary numbers. We've all been there at some point in our careers. A big difference between now and when this article appeared is that in 1958, almost nobody was familiar to binary numbers, and fuggetabout [sic] octal and hexadecimal. Only those relatively few people designing and working with multimillion dollar, vacuum tube-based digital computers installed in universities, megacorporations, and government research facilities had ever dealt with digital numbers. The earliest example of powers of two I remember was back in junior high school. It had to do with a

Art of Invention Constantly Reinvented

Art of Invention Constantly Reinvented - RF cafe"Every invention begins with a problem - and the creative act of seeing a problem where others might just see unchangeable reality. For one 5-year-old, the problem was simple: She liked to have her tummy rubbed as she fell asleep. But her mom, exhausted from working two jobs, often fell asleep herself while putting her daughter to bed. 'So [the girl] invented a teddy bear that would rub her belly for her,' explains Stephanie Couch, executive director of the Lemelson MIT Program. Its mission is to nurture the next generation of inventors and entrepreneurs. Anyone can learn to be an inventor, Couch says, given the right resources and encouragement. 'Invention doesn't come from some innate genius, it's not something that only really..."

Mechanical Filters

Mechanical Filters, April 1969 Electronics World - RF CafeMechanical filters of the type described in this 1969 Electronics World magazine article are yet another example of the genius of some people. They are actually a form of electromechanical device in that the applied electrical signals are first converted into mechanical signals, followed by resonant mechanical elements that discriminate according to frequency, and finally a conversion back to an electrical signal is made. It is fundamentally the same principal as a crystal, SAW, or BAW filter, albeit each with distinctly different methods and topologies. Mr. Donovan Southworth, of Collins Radio, presents the basics of mechanical filters in this brief write-up...

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.

Electronic Test Paper

Electronic Test Paper, July 1963 Radio-Electronics - RF CafeAttempts at making an electronically printed facsimile (fax) of an original document at a location distant from the source have been around for quite a while. As mentioned by Radio-Electronics magazine editor Hugo Gernsback in this article, Samuel Morse had a crude working device for printing messages on paper even before his eponymously named code of dots and dashes became famous in 1837. A couple decades earlier, a fellow named John Redman Coxe, of Philadelphia, Pennsylvania, devised a method of electronically printing images and text on paper using a conductive solution and a direct current pile (aka battery). Dr. Coxe, a physician, is not a well-known figure in the electronics world, but in his day...

"Edge of Chaos" High-Performance Microchips

"Edge of Chaos" High-Performance Microchips - RF Cafe"Researchers have discovered how the 'edge of chaos' can help electronic chips overcome signal losses, making chips simpler and more efficient. By using a metallic wire on a semi-stable material, this method allows for long metal lines to act like superconductors and amplify signals, potentially transforming chip design by eliminating the need for transistor amplifiers and reducing power usage. A stubbed toe immediately sends pain signals to the brain through several meters of axons, which are composed of highly resistive fleshy material. These axons operate using a principle known as the 'edge of chaos,' or semi-stability, enabling the swift and precise transmission of information..."

Japanese Trade-Name Directory

Japanese Trade-Name Directory, August 1969 Electronics World - RF CafeThe January 1969 issue of Electronics World magazine published an extensive list of Japanese company trade names and their addresses. Many of them went out of business or were bought by other corporations long ago, as occurs in all countries. "Aiwa" is listed twice, but that might have been a legitimate duplication due to separate locations (BTW, I owned an Aiwa stereo at one time). My first "real" cassette tape deck was made by TEAC (founded in 1953 as the Tokyo Electro Acoustic Company) and my first "real" stereo receiver was made by Sansui. I remember the line in "Back to the Future 3" where Doc Brown, having time-travelled from 1955, makes a disparaging remark about a circuit in the DeLorean failing because of it being labeled "Made in Japan." Marty counters...

Engineering & Tech Headlines <Archives>

• ARRL Defends 902-928 MHz Amateur Radio Band

• FCC's Auto Safety Spectrum Rules

• $5M in U.S. Chips Act Money to Metrology Projects

• U.S. State Department Approves Surveillance Radar System Sale to Romania

5G Americas ITU IMT-2030 Vision for 6G White Paper

John Redman Coxe: A Short Biography

John Redman Coxe: A Short Biography - RF Cafe - RF CafeJohn Redman Coxe was a prominent American physician, scientist, and innovator born on September 20, 1773, in Philadelphia. Coxe's intellect and curiosity drove him toward an illustrious career in both medicine and early scientific exploration, which included experimentation in electrochemistry. He graduated with a degree in medicine in 1794, setting the course for his lifelong journey into medicine and early scientific innovation. Coxe broadened his approach to medicine and science, inspiring him to explore the convergence of scientific methods and practical applications. John Redman Coxe is most remembered not only for his contributions to medicine but also for his interest in experimental physics, particularly in the field of electrochemistry...

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.

Vibration and Shock - Nature's Wrecking Crew

Vibration and Shock - Nature's Wrecking Crew, August 1966 Radio-Electronics - RF CafeWhen I saw this 1966 Radio-Electronics magazine article entitled, "Vibration and Shock - Nature's Wrecking Crew," for some reason the first thing I thought of was "The Wrecking Crew," that anonymously played the music for a huge number of popular singers - mostly those without prominent bands of their own during the 1960s and 1970s rock-and-roll era. ...but I digress. My introduction to the potential deleterious effects of vibration on electronics was in the 1970s, with airborne receivers and servos in my radio controlled model airplanes. Even though they were transistorized, vibration from glow fuel engines could wreak havoc with potentiometers in servos and solder joints everywhere, including battery packs. I remember seeing the control surfaces jitter...

Raytheon Needs Tube Design Engineers

Raytheon Manufacturing Company Needs Vacuum Tube Engineers, July 1944 QST - RF CafeYou don't see jobs advertisements like this anymore. Here is an ad that appeared in the the July 1944 edition of QST (the American Radio Relay League's, ARRL's, monthly magazine), placed by Raytheon Manufacturing Company (now just Raytheon Company), looking for vacuum tube design, test, and processing engineers. Licensed amateur radio operators were in high demand during the war years because of their knowledge and enthusiasm for electronics and wireless communications. I hope you didn't come to this page hoping to really find a tube designer job available. Of course, there are still vacuum tubes being designed for TWTs and magnetrons, but those are few and far between...

The Carborundum Signal Detector

The Carborundum Signal Detector - RF CafeThe "carborundum" signal detector, an innovative device developed by engineer General H. H. C. Dunwoody in the early 20th century, represents a significant advancement in radio technology, particularly in the context of crystal detectors used for receiving radio signals. This device utilized the unique properties of silicon carbide, also known as carborundum, which was synthesized in the late 19th century by Edward Goodrich Acheson. The connection between Dunwoody and the material lies in the application of carborundum as a semiconductor in radio signal detection. The operational theory of the carborundum signal detector is rooted in its ability to rectify alternating current (AC) signals. When radio waves, which are essentially electromagnetic waves...

Lossless Electronics with Innovative Quantum Sandwich

Lossless Electronics with Innovative Quantum Sandwich - RF Cafe"Researchers have created a cutting-edge structure by placing a very thin layer of a special insulating material between two magnetic layers. This new combination acts as a quantum anomalous Hall insulator, significantly broadening its potential use in developing ultra-efficient electronics and innovative solar technology. A Monash University-led research team has found that a structure featuring an ultra-thin topological insulator, sandwiched between two 2D ferromagnetic insulators, transforms into a large-bandgap quantum anomalous Hall insulator. This heterostructure opens the door to ultra-low energy electronics and even topological photovoltaics..."

Carl & Jerry: TV Picture

Carl & Jerry: TV Picture, June 1955 Popular Electronics - RF CafeTelevision, in 1955, was still a relatively new phenomenon to many - maybe even most - people. According to multiple sources, the portion of American households with a TV set went from under 20% in 1950 to nearly 90% ten years later in 1960. That was a meteoric rise, particularly considering the expense of even a minimal TV. The technology was not even available commercially when most people were born, so the rush to join in on the craze was akin to the mass adoption of cellphones in the 1990s. "Carl & Jerry" creator John Frye used his pair of electronics-savvy teenagers to help make the "magic" behind recreating a moving picture on a cathode ray tube (CRT) miles away from where it was created. Water flowing through a garden hose has often been employed as an analogy for current ...

Science Terms Crossword Puzzle for November 14th

Science Terms Crossword Puzzle for November 14th, 2021 - RF CafeThis technically themed crossword puzzle for November 14th contains only clues and words are directly to RF, microwave, and mm-wave engineering, optics, mathematics, chemistry, physics, and other science subjects. As always, this crossword contains no names of politicians, mountain ranges, exotic foods or plants, movie stars, or anything of the sort unless it/he/she is related to this puzzle's technology theme (e.g., Reginald Denny or the Tunguska event in Siberia). The technically inclined cruciverbalists amongst us will appreciate the effort. Enjoy!

Engineering & Science Crossword Puzzle for April 28

Engineering & Science Crossword Puzzle April 28, 2019 - RF CafeSince 2000, I have been creating custom science and 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...

Engineering Theme Crossword for March 21st

Engineering Theme Crossword Puzzle for March 21st, 2021 - RF CafeThis Engineering-Theme Crossword Puzzle for March 21st has many words and clues related to... you guessed it... engineering - including RF, microwave, optics, mathematics, chemistry, physics, and other technical subjects. As always, this crossword contains no names of politicians, mountain ranges, exotic foods or plants, movie stars, or anything of the sort unless it/he/she is related to this puzzle's technology theme (e.g., Hedy Lamarr or the Bikini Atoll). The technically inclined cruciverbalists amongst us will appreciate the effort. Enjoy!

Sentinel Model 217-P Portable Radio Set Radio Service Data Sheet

Sentinel Model 217-P Portable Radio Set Radio Service Data Sheet, August 1940 Radio-Craft - RF CafeMany months have passed since I last posted one of the Radio Service Data Sheets for vintage radio sets. This one for the Sentinel Model 217-P portable appeared in the August 1940 issue of Radio-Craft magazine. Hobbyists and professional electronics service shops relied on these back in the day because obtaining the information from manufacturers could be difficult or even impossible. Some companies would not provide service information for alignment and troubleshooting to businesses that were not officially endorsed to do so. That left some of the smaller shops and most do-it-yourselfers without a means to work on sets. Once places like SAMS Photofacts came along with information packets that could be purchased ...

OSCARs Help Dedicate New Air and Space Museum

OSCARs Help Dedicate New Air and Space Museum, September 1976 QST - RF CafeThat would be President Ford in the background atop the platform, behind where the OSCAR ground station was set up. He was there as part of the dedication of the new National Air & Space Museum in Washington, D.C., in 1976. The event was part of the nationwide series of bicentennial celebrations marking America's founding with the signing of the The unanimous Declaration of the thirteen united States of America. Apollo 11 astronaut Michael Collins directed the event. The Space Race was in its heyday and most people were still in awe of anything related to spacecraft - both manned and unmanned. Just about anyone other than a Ham radio operator believed communicating with a satellite was the exclusive domain of governments, so the presence of AMSAT...

The Color TV X-Ray Problem

The Color TV X-Ray Problem, November 1968 Radio-Electronics - RF CafeWhen you were a kid, did your mother warn you about sitting too close to the television because doing so would cause you to be near-sighted or otherwise "ruin" your eyes? Mine did, and I'm now very near-sighted, but it is doubtful that sitting too close to the TV is the reason. In fact, according to Linus Van Pelt's comments to his sister, Lucy, in this 1962 Peanuts comic strip, ophthalmologists tried to counter the misconception about too-close boob tube viewing. There is another strip where Linus challenges Lucy's assertion that reading in dim lighting can hurt your eyes. The real concern as it turns out, according to professional alarmists, was the massive doses of x-radiation pouring out of the front of the early color TV sets. To hear the distractors tell it, you could almost see the skeleton of anyone sitting in close proximity to a color TV screen. The high voltage (25-35 kV) on the cathode ray tube (CRT) produced x-rays...

Roll Your Own Capacitors

Roll Your Own Capacitors, January 1956 Popular Electronics - RF CafeHere is another instance that shows how much expectations have changed over the years. Except maybe for an experimenter or someone set on reproducing original equipment as closely as possible, nobody would even consider trying to build capacitors from scratch. Compared to when this "Roll Your Own Capacitors" story appeared in a 1956 issue of Popular Electronics magazine, components nowadays are so inexpensive that it's just not worth the trouble. If you are one of the extreme do-it-yourself type people, then this story is for you. Come to think of it, another use for this article is to provide material for a physics class laboratory exercise where the student calculates a predicted value for capacitance based on surface area, dielectric constant, and plate separation distance...

Behind the U.L. Label

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

Lady Television Engineer

Lady Television Engineer - Cover Story, November 1949 Radio-Electronics - RF CafeThere is no denying that in 19th and 20th Century America and most other industrialized countries, non-white males dominated the academic, commercial, and industrial design and service workforce. Societal norms were much different in those times, and the truth is most women did not desire to enter into the "professional" market. Many performed low skill labor and assembly functions, serving an essential yet less demanding role in providing goods and services for the world. This 1949 "Lady Television Engineer" story appearing in Radio-Electronics magazine celebrated Tex Barbarite as a ground-breaking and glass-ceiling-breaking woman in the commercial television broadcast industry. As was common in the era, Ms. Barbarite's public platform was used to give encouraging insight into her path to success - not to complain and dwell on resistance met in her effort. BTW, would it be politically incorrect to point out, as evidenced by the complaints of others, that it was mostly White males who envisioned and created the most of the modern world...

RF & Electronics Symbols for Office™

RF & Electronics Schematic & Block Diagram Symbols for Office™ r2 - RF CafeIt was a lot of work, but I finally finished a version of the "RF & Electronics Schematic & Block Diagram Symbols"" that works well with Microsoft Office™ programs Word™, Excel™, and Power Point™. This is an equivalent of the extensive set of amplifier, mixer, filter, switch, connector, waveguide, digital, analog, antenna, and other commonly used symbols for system block diagrams and schematics created for Visio™. Each of the 1,000+ symbols was exported individually from Visio in the EMF file format, then imported into Word on a Drawing Canvas. The EMF format allows an image to be scaled up or down without becoming pixelated, so all the shapes can be resized in a document and still look good. The imported symbols can also be UnGrouped into their original constituent parts for editing...

Honeywell HE-240A Whole House Humidifier Installation

Honeywell HE240A Whole House Humidifier Installation - RF CafeA large portion of the U.S. has experienced prolonged periods this winter with temperatures substantially below long-term averages. That means heating systems have been running much more often than usual, and if you have a forced hot air system, that means the indoor humidity level has been much lower than normal. In northern areas like where I live, humidity can easily drop to near zero. Because of that, triboelectric charging to high voltage potential occurs merely by walking a few steps across a carpet, resulting in a sometimes painful discharge arc when a metal object is touched. The only way to mitigate low humidity conditions is to add water back into the air. The preferred option, IMHO, is to install a whole-house humidifier that resides on the furnace ductwork, has its own regulated water supply, and is controlled by a humidistat. After a couple weeks of refilling three free-standing humidifiers two to three times a day and listening to the fans, I decided it would be worth the expense and effort to install a whole-house humidifier. The Honeywell HE240A whole-house humidifier with a couple additional parts...

How to Target RFCafe.com for Your Google Ads

Google AdSense - it makes good sense - <em>RF Cafe</em>One aspect of advertising on the RF Cafe website I have not covered is using Google AdSense. The reason is that I never took the time to explore how - or even whether it is possible - to target a specific website for displaying your banner ads. A couple display opportunities have always been provided for Google Ads to display, but the vast majority of advertising on RF Cafe is done via private advertisers. That is, companies deal with me directly and I handle inserting their banner ads into the html page code that randomly selects and displays them. My advertising scheme is what the industry refers to as a "Tenancy Campaign," whereby a flat price per month is paid regardless of number of impressions or clicks. It is the simplest format and has seemed to work well for many companies. With nearly 4 million pageviews per year for RFCafe.com, the average impression rate per banner ad is about 225,000k per year (in eight locations on each page, with >17k pages)...

Electrical Power / Force, NAVPERS 10622

Chapter 7: Electrical Power / Force, NAVPERS 10622 - RF CafePower, energy, force, and work are all physical entities whose definitions are often incorrectly interchanged. As with most cases in physics, knowing the unit associated with each entity is a way to remember what it represents. For instance, force is fundamentally understood as a mass being acted upon by an acceleration - whether it be gravity or motion. Its SI units are kg·m/s2 (newton, with dimensions of mass x length / time2). Energy is a force in motion (or its potential by virtue of relative position) with units of force x mass (joule, with dimensions of mass x length2 / time2), and an electrical unit of watt·seconds (power x time). Work is force through a distance, with dimensions of mass x length2 / time2, which is the same ...

Theory and Construction of Attenuators, Line Filters and Matching Transformers

The Theory and Construction of Attenuators, Line Filters and Matching Transformers, June 1932 Radio-Craft - RF CafeIt seems most of the articles we see on the subject of attenuator pads are based on signal reduction in terms of decibels for units of power. Although it is a simple matter to convert power decibels to voltage decibels, it would be more convenient if you are working with voltage to have formulas and tables of values based on voltage ratios. This article does just that. As a reminder, the decibel representation of a ratio is always 10 * log10 (x). If you have a voltage ratio of V1/V2 = 0.5, then 10 * log10 (0.5) = -3.01 dB. If you have a power ratio of P1/P2 = 0.5, then 10 * log10 (0.5) = -3.01 dB. Does that mean that -3.01 dB of voltage attenuation is the same as 3.01 dB of power attenuation? Confusingly, no. Let's say for the sake of simplicity that you have 1 V across a 1 Ω resistor...

Generators, Electricity - Basic Navy Training Courses

NAVPERS 10622, Chapter 14 - Generators, Electricity - Basic Navy Training Courses - RF CafeIn keeping with a very common practice of using water flowing through a garden hose as a teaching aid analogy for newcomers, the title of this chapter of the NAVPER 10622 Basic Navy Training Courses, "Generators - Electrical Pumps," is likening electrical generators to water pumps. It is an apt analogy, but whereas a water pump can cause water pressure and flow of a physical substance already on-hand, electrical "pumps," aka generators, literally creates its "flow" from thin air (even a vacuum with no air). An electrical generator exploits the phenomenon discovered by (or at least credited to) Michael Faraday whereby a conductor moving through a magnetic field - or a magnetic field moving past a conductor ...

The Aircraft Radio Serviceman

The Aircraft Radio Serviceman (Piper Cub), April 1946 Radio News - RF CafeAircraft electronics has always been on the bleeding edge of technology because of the ever-increasing need to fly in the widest range of atmospheric conditions possible. Accordingly, skills needed by avionics servicemen are amongst the highest required in any electronics field. There are still many pieces of vintage equipment in service that need to be maintained, but even 20- to 30-year-old airborne radars and navigational units require top-notch techs to troubleshoot and align. One topic in particular that plagues electronics operation even in modern airframes is that of static electricity build-up and lightning strikes. We all face those kinds of static discharge hazards in non-aviation environments, but for the most part a failure on the ground or water is not as imminently life-threatening as a failure in the air...

Hallicrafters Radio TG-10-F Radio Keyer

Hallicrafters Radio TG-10-F Radio Keyer, October 1945 Radio-Craft - RF CafeInterestingly, when I searched for the Hallicrafters TG-10-F Radio Keyer, the first thing that came up was an eBay offering for a Gray Manufacturing Army Signal Corps "Keyer TG-10-F" Morse Code Practice Machine. Evidently more than one manufacturer was contracted to make the model. It looks like a tape record / playback machine, but it feeds a reel of paper strips with dots and dashes followed by straight lines forming letters and words. An optical reader encodes the audio signal for code practice students - up to 300 at a time using the built-in amplifier. Morse code was a primary mode of communication during World War II because the transmit and receive equipment was simple and reliable, and could perform acceptable in the presence of noise and weak signals. It also had the advantage of some level of privacy since most people could not understand code, especially when sent at high data rates (WPM). There does not seem to be a feed speed adjustment on the control panel... (see update on Technical Manual)

Engineering & Science Crossword Puzzle for December 29

Engineering & Science Crossword Puzzle December 29, 2019 - RF CafeThis week's engineering crossword puzzle features a special end-of-the decade message, comprised of three words and clues, for RF Cafe visitors. As with my hundreds of previous engineering and science-themed crossword puzzles, this one contains only clues and terms associated with engineering, science, physical, astronomy, mathematics, chemistry, etc., which I have built up over nearly two decades. Many new words and company names have been added that had not even been created when I started in the year 2002. 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 ...

Computing the Harmonic Content of Any Given Periodic Complex Waveform

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

LadyBug LB5954L Power Sensor with LAN Option - RF Cafe
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Windfreak Technologies Frequency Synthesizers - RF Cafe