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Homepage Archive - April 2021 (page 2)

See Page 1 | 2 | 3 | 4 of the April 2021 homepage archives.

Wednesday the 14th

The Electron Tube

The Electron Tube, November 1954 Radio & Television News - RF CafeHere in this 1954 issue of Radio & Television News magazine is one man's (Commander Paul G. Watson, USNR (ret.) collection of early vacuum tubes and a bit about them. It reaches back to Dr. Lee de Forest's farther than even earliest Audion tubes - including the "UltraAudion" - to include the flame-based detector and amplifiers he worked on. For a very thorough history of de Forest's work from the vantage point of both the good Dr. and those who worked with him, including a story by William Howard McCandless (the man who's glass blowing business built the various tubes for de Forest), check out the January 1947 issue of Radio-Craft magazine. It celebrated the 40th anniversary of the de Forest Audio tube. I wonder where this collection of tubes is today. Many priceless collections of technical history artifacts end up being mistakenly or ignorantly disposed of...

2021 to Be Record Year for Semiconductors

2021 to Be Record Year for Semiconductors - RF Cafe"Total semiconductor unit shipments, which include integrated circuits as well as optoelectronics, sensor/actuator, and discrete (O-S-D) devices, are forecast to rise 13% in 2021, to 1,135.3B (1.1353T) units to set a new all-time annual record, according to IC Insights' McClean Report - A Complete Analysis and Forecast of the Integrated Circuit Industry. It would mark the third time that semiconductor units have surpassed one trillion units in a calendar year - the first time being in 2018. The 13% increase to 1,135.3B semiconductor units follows a 3% increase in 2020..."

RF Cafe Quiz #55: Conquer Radio Frequency

RF Cafe Quiz #55: Conquer Radio FrequencyThis quiz is based on the information presented in Conquer Radio Frequency, by Francesco Fornetti. See my review for the online version. This material, which includes a full-color textbook and over 12 hours of video tutorials (in mp4 format on enclosed DVD-R), provides a comprehensive guide for the RF and Microwave engineering student or junior professional. It allows the reader to achieve a good understanding of the foundation theory and concepts behind high frequency circuits as well illustrating the most common design and simulation techniques for passive and active RF circuits. A preview of the textbook, a comprehensive description of the content of the video tutorials and sample video tutorials are available on the Explore RF website.

The Engineering Essentials Behind LiDAR 

The Engineering Essentials Behind LiDAR - RF CafeEdel Cashman has a good article on the Electronic Design website entitled, "The Engineering Essentials Behind LiDAR." LiDAR works by the same principles as sonar and radar, but rather than sound and radio frequencies, it uses light. Its extremely short wavelengths makes it ideal for high precision positioning and navigation - such as with autonomous vehicles. Mr. Cashman (great name, BTW!) begins, "LiDAR (light detection and ranging)... applies the principles of reflected light and accurate timing to measure the distance of an object. LiDAR permits superior depth sensing due to its high levels of depth and angular resolution. In addition, it's able to operate in all light conditions due to the active approach that uses an infrared light transmitter along with a receiver. However, LiDAR is more sophisticated than just a distance measure. It can also be used in 3D mapping and imaging, making it very appealing in an engineering context as well as a very useful practical technology. There are different approaches to LiDAR..."

Belmont 4-Tube Model 408 Battery "Farm" Superhet

Belmont 4-Tube Model 408 (Series A) Battery "Farm" Superhet Radio Service Data Sheet, October 1938 Radio-Craft - RF CafeAt least for now, I am going to only scan and post Radio Service Data Sheets like this one featuring the Belmont 4-Tube Model 408 (Series A) Battery "Farm" Superhet radio in graphical format, rather than run OCR on them to separate the textual content. It appeared in the October 1938 issue of Radio-Craft magazine. There are still many people who restore and service these vintage radios, and often it can be difficult or impossible to find schematics and/or tuning information. No example of this radio could be found on the WWW...

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 267,269 products from more than 1397 companies across 314 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.

Tuesday the 13th

Coming in September Popular Electronics

Coming in September Popular Electronics, August 1954 Radio & Television News - RF CafeBefore seeing this announcement for the impending premier issue of Popular Electronics magazine, I though the October 1954 issue was the first to be published. According to this August 1954 Radio & Television News magazine feature, Popular Electronics was to debut in September 1954, not October. The teaser cover photo showed a family at a picnic table with more radio equipment than food - including a big spring-loaded 1/4-wave whip antenna mounted to the trunk of their car. It was never used for any issue from what I can find, nor did the article entitled, "WABD's Empire State Building Television Transmitter." A bit of research shows that the planned September 1954 issue never was. In fact, editor Oliver Read's first column, entitled, "Meet Popular Electronics," confirmed my finding. He wrote in part, "POPULAR ELECTRONICS is the answer to the demand for a monthly publication devoted entirely to electronics..."

Amateur Radio Contesting Faces Demographic Cliff

Amateur Radio Contesting Faces Demographic Cliff - RF Cafe"Frank Howell, K4FMH, followed up his two-part National Contest Journal (NCJ) series, 'The Demographics of Contesting,' with a post to his Social Circuits blog, called 'Lemmings over a Demographic Cliff?' Howell points to data showing that radio contesters are older than the average ARRL member. Taking into account information from the Bureau of Labor and Statistics on Leisure Time Use, Howell opines that this should be expected. 'Leisure pursuits are highest during youth and young adulthood but dramatically taper off about ages 25 - 34 until age 55 and over,' Howell said. 'This hollowing out of leisure and sport time is a predictable outcome of competing and more important activities.” According to Howell, the main competitor to radio amateurs engaging in on-the-air or workshop activities is television. No surprise there..."

Vintage Heathkit GR-48 AM/FM Table Radio Kit

Vintage Heathkit GR-48 AM/FM Table Radio - RF Cafe Cool ProductVintage Heathkit GR-48 AM/FM Table Radio Kit - RF Cafe Cool ProductThis vintage Heathkit GR−48 AM/FM Table Radio kit just showed up on eBay, and will be on auction until Monday, April 19th, 2021 (in case you would like to bid). The listing states it is of 1969 vintage, but the GR−36 shows up in the 1969 Heathkit catalog; the GR−48 first appears in 1970. Photos of the kit are from the current GR−48 listing noted above, and photos of the fully built kit are from an expired GR−48 listing. In the interest of preserving the memory of Heathkit's great legacy in the electronics realm, I have been looking for examples of unbuilt kits on eBay and posting some of the photos here on RF Cafe. Heathkit products were well known for the completeness of its instruction manuals, with clearly illustrated instructions. During the writing and editing process, Heathkit employees were given pre-production kits to take home and build, while annotating any difficulties or errors encountered. Doing so helped minimize the situation where the writer inadvertently assumes his own familiarity with the process is shared by the customer...

New for 2021! 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 or so 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. Check them out!

Many Thanks to KR Electronics for Helping Deliver RF Cafe!

KR ElectronicsKR Electronics designs and manufactures high quality filters for both the commercial and military markets. KR Electronics' line of filters includes lowpass, highpass, bandpass, bandstop and individually synthesized filters for special applications - both commercial and military. State of the art computer synthesis, analysis and test methods are used to meet the most challenging specifications. All common connector types and package form factors are available. Please visit their website today to see how they might be of assistance. Products are designed and manufactured in the USA.

Monday the 12th

Radio Term Illustrated - "Cross" Modulation

Radio Term Illustrated - "Cross" Modulation, December 1939 Radio News - RF CafeHere is another of the "Radio Term Illustrated" type of comic, which appeared in the December 1939 issue of Radio News magazine. The DXing Hams can get a bit animated when trying to squeeze the last picowatt out of a long distance contact. I'm not sure why the guy is depicted as a country hick when for certain there were plenty of polished city slickers who resorted to the same antics. A big list of other electronics-themed comics is at the bottom of the page, many of which contain other of the "Radio Term Illustrated" style.

Comparing 5G Progress in U.S. and China

Comparing 5G Progress in U.S. and China - RF Cafe"China and the U.S. continue to top the 5G charts, with VIAVI's The State of 5G Deployments report showing that the countries have 341 and 279 5G-connected cities, respectively. In China, the number of cities with 5G grew six-fold in one year, while coverage in the U.S. increased by a factor of five. Further, in Ericsson's November Mobility Report, 220 million 5G subscriptions were expected by the end of 2020, an estimation that the company increased as a result of China's faster-than-expected uptake, which was 'driven by a national strategic focus, intense competition between service providers and more affordable 5G smartphones from several vendors.' Chinese telecom carriers are expected to build over 1 million new 5G base stations in 2021..."

A Great Cache of Electronics-Related Technical Papers

A Great Cache of Electronics-Related Technical Papers - RF CafeJames A. Crawford, proprietor of AM1 LLC, has written and published a large collection of electronics-related technical papers available for download. Topics include antennas, communication systems, design reviews, digital signal processing, frequency synthesizers, modems, orthogonal frequency division multiplex (OFDM), oscillators, phase-locked loops, phase noise, technical proposal writing, radio design, RF design, software defined radio (SDR), tunable filters, WLAN, and much more. He is also the author of a book entitled, "Advanced Phase-Lock Techniques." You might enjoy his "Dreaded Interview Questions for Fun" paper to see how well you do answering the questions. BTW, I didn't get the job ;-(

Multiband Active Antenna Tuner for Cellular IoT

Multiband Active Antenna Tuner - RF CafeDavid Vye has an article on the High Frequency Electronics website entitled, "Multiband Active Antenna Tuner for Cellular IoT Applications," that introduces the concept of a device that can maintain a reasonable impedance match between the transceiver and antenna over a wide bandwidth. This is different than an active antenna steering device. Because wireless products (smartphones, tablets, etc.) a nowadays required to accommodate many frequency bands over a large range of spectrum, traditional methods of switched Tx/Rx paths according to the selected band of operation are getting bulky and expensive since they include a number of discrete components. Mr. Vye begins, "With the release of each new generation of wireless technology since the introduction of the portable phone in the early 1980s, mobile communications have progressed exponentially. Each generation has launched new services and business opportunities, leading up to what is being referred to as the 'third wave' of communications..."

Amateur Radio Stations - VE2CP

Amateur Radio Stations - VE2CP, December 1931 QST - RF CafeWhen the caption for a photograph in a 1931 article refers to an "antiquated" motor, you can be sure you're looking at a really old motor. Indeed it does look very old. Whenever I see vintage photos or films of electrical / electronic apparati [sic] and operators, I always look for safety issues like no eye protection while soldering or when using powered tools to fabricate enclosures, lack of protective shields around electrical connections and mechanical drive mechanisms, wearing of inappropriate clothing near rotating machinery, etc. In this case you can see a very long, totally exposed drive belt running between that aforementioned antiquated motor and DC generator that it drives (to power the transmitter). The author mentions how the floor shook while it was running...

RF Cascade Workbook 2018

RF Cascade Workbook 2018 Is Available Now! - RF CafeRF Cascade Workbook 2018 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 2018 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. An intro video takes you through the main features...

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.

Sunday the 11th

Microwave Engineering Theme Crossword Puzzle for April 11th

Microwave Engineering Theme Crossword Puzzle for April 11th, 2021 - RF CafeThis Microwave Engineering Crossword Puzzle for April 11th has many words and clues related to RF, microwave, and mm-wave engineering, 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., Reginald Denny or the Tunguska event in Siberia). The technically inclined cruciverbalists amongst us will appreciate the effort. Enjoy!

Friday the 9th

The Growth of Radio

The Growth of Radio, April 1946, Radio-Craft - RF CafeIn his April 1946 Radio-Craft editorial column, Hugo Gernsback reflected on the great advances made during the past half-decade's war efforts, and predicts that the field of radio-electronics will see explosive growth. Of course it didn't require Mr. Gernsback's usual extraordinary visionary skills to make such a claim at that time. Cyclotrons, Betatrons, VHF, UHF, and microwave amplifiers and vacuum tubes, cathode-ray tubes, transmission lines, waveguide, and countless other technologies had recently been developed anew or improved from pre-war designs. Engineers and technicians were to benefit greatly from the advances, as would, eventually, consumers who would be buying the wonderful new products made from those newfangled devices. Coming soon - likely much to his surprise...

Massive Swarms of Deadly Drones

Massive Swarms of Deadly Drones - RF Cafe"The Pentagon has announced that one of its offices has completed planned research and development work on a number of unmanned drone swarming technologies and has now turned them over to the U.S. Air Force, Army, Navy, and Marine Corps to support various follow-on programs. The systems in question are the Block 3 version of Raytheon's Coyote unmanned aircraft and an associated launcher, a jam-resistant datalink, and a software package to enable the aforementioned drones to operate as an autonomous swarm. These developments give us a glimpse into what has been a fairly opaque, integrated development effort to field lower-end swarming drones across the services that leverages common components. All of these technologies were developed under the auspices of the LCCM effort, led by the Pentagon's JCTD program office..."

Wireless Communications Fundamentals Quiz

RF Cafe Quiz #6: Wireless Communications Fundamentals - RF CafeAll 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. This particular quiz challenges your knowledge of Wireless Communications Fundamentals, including questions on standards, terminology, and components. Bonne chance, Viel Glück, がんばろう, buena suerte, удачи, in bocca al lupo, 행운을 빕니다, ádh mór, בהצלחה, lykke til, 祝你好運. Well, you know what I mean: Good luck!

Changji-Guquan UHV DC Transmission Link in Anhui, China

Changji-Guquan UHV DC Transmission Link in Anhui Province, China - RF Cafe Cool PicWhen up in a small airplane or helicopter, I have never had any sense of fear of heights, but when at the top edge of a really tall building or at the precipice of a high cliff, the need to control the panic sensation is required. It is not strong enough to prevent me from going there, but I'm definitely not one of those fearless types that will go anywhere with reckless abandon. Even seeing a photo like this one on the IEEE Spectrum website invokes the fight or flight emotion. You need to click on the thumbnail to see the larger version to really get a sense of the height at which the technicians are working. The story is about China's Changji-Guquan ultrahigh-voltage direct-current transmission link along the Yangtze River, in Anhui province. Arguments abound over whether DC or AC is better overall for electrical distribution, but the main reason for this DC line is to accommodate energy storage at locations throughout the country...

Many Thanks to ISOTEC for Continued Support!

ISOTEC Corporation - RF CafeSince 1996, ISOTEC has designed, developed and manufactured an extensive line of RF/microwave connectors, between-series adapters, RF components and filters for wireless service providers including non-magnetic connectors for quantum computing and MRI equipments etc. ISOTEC's product line includes low-PIM RF connectors components such as power dividers and directional couplers. Off-the-shelf and customized products up to 40 GHz and our low-PIM products can meet -160 dBc with 2 tones and 20 W test. Quick prototyping, advanced in-house testing and high-performance. Designs that are cost effective practical and repeatable.

Thursday the 8th

Theory and Application of U.H.F.

Theory and Application of U.H.F., October 1944 Radio News - RF CafeThis seventh installment in an eleven-part series on "Theory and Application of U.H.F." appeared in the October 1944 issue of Radio News magazine. Author Milton Kiver covered a wide range of topics including basic and advanced circuits, tube types, modulation, resonant cavities, oscillators, transmission lines, waveguides, antennas, electromagnetic fields, and Maxwell's equations. Part 7 continued the discussion of how waveguides, both rectangular and circular, support the conduction of electromagnetic waves. Methods for injecting and extracting signals is covered as well. Interestingly, the Smith chart never appeared even though Phillip H. Smith had introduced it around 1936. In fact, the first mention of the Smith Chart in Radio News, per a WWW search, was in 1950...

GaN RF Devices Critical for Higher Frequency 5G

GaN RF Devices Critical for Higher Frequency 5G - RF Cafe"Telecom operators around the world are deploying 5G using higher frequencies in both the sub-6GHz band and mm-wave bands. This has pushed OEMs to look for new antenna technology platforms with larger bandwidths, higher efficiency, and better thermal management. GaN technology has become a serious competitor to LDMOS and GaAs in RF power applications, showing continuous performance and reliability improvement leading, potentially, to a lower cost at the system level. Yole expects the total GaN RF device market to go beyond US$2 billion in sales by 2025 with a 12% CAGR between 2019 and 2025. In the dynamic 5G infrastructure market, there is a continuous race for more efficient antenna types. Switching technology from Remote Radio Head (RRH) to Active Antenna System (AAS) will transform the RF front ends..."

Testers, Beware of this April 1st Prankster

Beware of this April 1st Prankster - RF CafeWho doesn't like a good practical joke - especially if it's played on someone else while you watch? This "Testers, Beware of this April 1st Prankster" story appears on the Electronics Design website. It trumps the one I fondly recall from my days as a technician at Westinghouse Electric in the 1980s. On the evening shift, we used to get away with playing practical jokes on each other in the lab; new hires were sure to get the treatment. Ours were low tech stuff like connecting a high voltage supply to someone's metal toolbox or squeezing water from a soldering iron sponge wetting bottle through a length of plastic tubing (taped under a workbench) onto a guy's crotch while he was working intently on something. You'd probably get fired or sued for such shenanigans in the workplace today.

Post Your Engineer & Technician Job Openings on RF Cafe for Free

Engineering Job Board - RF CafeRF Cafe's raison d'être is and always has been to provide useful, quality content for engineers, technicians, engineering managers, students, and hobbyists. Part of that mission is offering to post applicable job openings. HR department employees and/or managers of hiring companies are welcome to submit opportunities for posting at no charge. 3rd party recruiters and temp agencies are not included so as to assure a high quality of listings. Please read through the easy procedure to benefit from RF Cafe's high quality visitors...

Allen-Bradley Resistors Advertisement

Allen-Bradley Resistors Advertisement, December 1931 QST - RF CafeAllen-Bradley has been making resistors for a long time, as evidenced by this advertisement from the December 1931 edition of the ARRL's QST magazine. From my earliest days in electronics in the 1970s, I remember using their products in hobby projects and then later in professional applications. Rockwell Automation now owns Allen-Bradley, so if you want historical information, you will have to do a search for pages like this one. According to Wikipedia: "The company was initially founded as the Compression Rheostat Company by Dr. Stanton Allen and Lynde Bradley with an initial investment of $1,000 in 1903. In 1910 the company was renamed the Allen-Bradley Company."

Conduct RF Phase & Temperature Stable Cables

Conduct RF Phase & Temperature Stable Cables april 2021 - RF CafeConductRF, a manufacturer of precision RF coaxial cable assemblies and connectors, announces the availability of Phase Stable / Temperature Stable solutions for both commercial and laboratory precision RF applications. 50 ppm phase accuracy with temperature phase matching capabilities, low loss and high power options, broad connector choices. Manufacturing capabilities include solutions built at our ITAR registered facility in Methuen, Massachusetts, as well as partner facilities in the U.S. and around the world. ConductRF offers cost effective equivalent and improved RF solutions to all major interconnect manufacturers, specializing in phase stability over temperature...

Please Thank IPP for Their Long-Time Support!

Innovative Power ProductsInnovative Power Products (IPP) has over 30 years of experience designing & manufacturing RF & microwave passive components. Their high power, broadband couplers, combiners, resistors, baluns, terminations and attenuators are fabricated using the latest materials and design tools available, resulting in unrivaled product performance. Applications in military, medical, industrial and commercial markets are serviced around the world. Please take a couple minutes to visit their website and see how IPP can help you today.


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    Kirt Blattenberger,


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

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