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About RF Cafe

Kirt Blattenberger - RF Cafe Webmaster

Copyright: 1996 - 2024


    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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Homepage Archive - November 2020 (page 3)

See Page 1 | 2 | 3 | 4 | 5 of the November 2020 homepage archives.

Friday 21

New Tube Improves FM

New Tube Improves FM, December 1947 Radio-Craft - RF CafeGeneral Electric's 19T8 vacuum tube was more than just a high frequency diode-triode component for use in the upper radio and television circuits. It also included a dual-diode element which was physically associated with the cathode of the triode side of the tube. It is meant to be used in combination AM / FM receivers operating up to 100 MHz. Its 18.9 V heater voltage is higher than the much more common 6.3 V and 12.6 V levels (note integer multiples of 6.3, including 25.2V sometimes used).From the limited information I could find about the 19T8, it was not as widely used as the 6T8...

RF Technology Trends for Satellite Communication Device Design

4 RF Technology Trends for Satellite Communication Device Design - RF Ccafe"Over the past four decades, the sheer amount and complexity of information transmitted through satellite communication has substantially increased. At the same time, more mission-critical applications - such as aeronautical, maritime, and military navigation - have become increasingly reliant on these communications. As a result, the RF circuit building blocks that make up satcom technology have been through many changes to accommodate the latest advancements in the industry including miniaturization, increased reliability, and the ability to rapidly transmit even more complex data. This article examines four RF technology trends..."

Many Thanks to Electro-Photonics for Their Continued Support

Electro-PhotonicsElectro-Photonics is a global supplier of RF & Microwave components. Their products include SMT hybrid and directional couplers, wire bondable passive components, mounting tabs, filters, transmission lines, and very useful test boards for evaluating components (spiral inductors, single-layer capacitors). The Electro-Photonics team can support your small R&D design requirements with RF & Microwave test fixtures and save you valuable design and characterization time. Please take a moment to visit Electro-Photonics' website and see how your project might benefit. 

Delco Radio Advertisement

Delco Radio Advertisement, June 1944 QST - RF CafeHere is an advertisement for Delco Radio that I scanned from page 77 of my copy of the June 1944 QST magazine. "What's Magic About Electrons?," is the question asked. Answer: "The magic about electrons is man's ingenuity in putting them to work. The magic about electrons is their promise of service in marvelous ways only hinted at in the last few years. Now harnessed for war, the science of electrons will later work to enrich the peace. Working in close cooperation with Army and Navy engineers, Delco Radio has applied its knowledge and skill in putting electronics actively and effectively into the fight for Victory. In Delco's laboratories, principles are explored and exploited; in Delco's engineering departments, designs are evolved to apply these principles; and on Delco's production line, complete equipment is manufactured with the speed and skill that only a large manufacturer of precision radio instruments can bring to such work..."

Research Biomedical / Electrical Engineering Opportunity

Research Biomedical/Electrical Engineering Opportunity - RF CafeThis could be the opportunity of a lifetime. There is no better job security today than working in the medical field - especially at a prestigious institution. The Biomaterials Laboratory of the Martinos Center for Biomedical Imaging is seeking a research biomedical or electrical engineer to participate in an exciting five-year NIH-funded project to participate in the development of a specialized MRI scanner and carry out a program of research on bone and osteoporosis. The successful candidate will work on hardware, software and algorithm development. He/she must have a B.S. or M.S. degree in a relevant engineering field and experience with MRI, most preferably MRI coil design...

Please Visit Triad RF Systems to Thank Them for Their Support

Triad RF SystemsTriad RF Systems designs and manufactures RF power amplifiers and systems. Triad RF Systems comprises three partners (hence 'Triad') with over 40 years of accumulated knowledge of what is required to design, manufacture, market, sell and service RF/Microwave amplifiers and amplifier systems. PA, LNA, bi-directional, and frequency translating amplifiers are available, in formats including tower mount, benchtop, rack mount, and chassis mount. "We view Triad more as a technology partner than a vendor for our line-of-sight communications product line." Please check to see how they can help your project.

Thursday 20

Electronics-Themed Comics

Electronics-Themed Comics, July 1951 Radio & Television News - RF CafeThe early 1950s was a time when people worldwide were making a shift from radio to television as the primary form of in-home entertainment. There was an aura of awe associated with TV with its ability to send recorded movies and live shows over the air without any physical connection (although it can be argued that an electromagnetic wave is "physical," since it is part of the study of physics). Of course often times the feeling of awe was replaced by a feeling of rage when the blasted thing went on the fritz. Then, the television repairman became the objet d'awe (I just made up that phrase, a la objet d'art). Two of these three tech-themed comics are typical of the era. The other is timeless and could be a modern comic if something other than vacuum tube equipment was shown in the scene. Enjoy!

PCBA Manufacturing Process Video

PCBONLINE Blog: The PCBA Manufacturing Process Video - RF CafePCBONLINE, a one-stop custom PCB/PCBA manufacturer for prototypes, small-batch, and massive production, has a short video showing their PCBA manufacturing process. It begins with the solder paste application using an SMT component attachment pad stencil, shows the pick-and-place operation (always a mesmerizing things to watch), progresses to the temperature profiled reflow oven and if needed for through-hole components a wave soldering step, then goes to machine vision and human inspection, and finally an electrical test is performed. Any necessary rework is performed by a trained technician. For many electronics product manufacturers, PCB assembly is necessary and vital to their products. PCBONLINE, a one-stop PCB/PCBA manufacturer since 1999...

Coiled Conductive-Thread Actuators Emulate Muscle Motion

Coiled Conductive-Thread Actuators Emulate Muscle Motion - RF Cafe"The quest to replicate the flexibility, controllability, and dexterity of human muscles and associated limbs has inspired some truly 'non-obvious' but highly workable actuator concepts. For example, actuators comprised of twisted threads that have been tightly wound around a mandrel can 'pull-in' along their axis as the thread is heated—either by an tiny internal heater or by using conductive threads and self-heating—and then lengthens. Called twisted-coil actuators (TCAs), these devices can be fabricated in various ways to provide types of motion that remarkably resemble a human muscle in action or even an octopus tentacle. And the amount of force they can develop is surprisingly high. However, existing TCA-actuated soft robots can only generate simple motion, since TCAs fabricated with conventional methods must be preloaded to generate a large contraction and thus can't actuate soft robots properly..."

USAF Entrance Test

USAF Entrance Test from 1973 Popular Mechanics - RF CafeA few days ago, I was perusing an April 1973 edition of Popular Mechanics magazine, when I ran across the following full-page ad with a U.S. Air Force enlistment aptitude test. Take the test, and if you get the same answers as the geniuses that created the ad, you're a shoe-in for a great career in the USAF! Uncle Sam wants you, bay-bee. I did the first two tests and got what they got for answers. Then I took the third test - the one with the little folded house - and was shocked at what I found. You take the three tests, and see if you think something is amiss with the last one. Look way down at the bottom of the page for my conclusion...

Lectrix to Host "Engineering the Conversation" Online Conference

Lectrix to Host Engineering the Conversation Online Conference - RF CafeElectronics industry sales and marketing expert Lectrix is hosting "Engineering the Conversation" on December 8th & 9th. Engineering the Conversation is a free, 2-day online conference for professionals managing sales and marketing in the B2B electronics industry. "So much has changed on the sales and marketing side of the industry in the last 9 to 10 months, that there is a lot to be said and learned from each other," said Graham Kilshaw, CEO of Lectrix. "This virtual conference is a community event for the electronics industry; it allows attendees to interact and network with speakers and each other to exchange the latest ideas and solutions on how to respond to the pandemic..."

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.

Wednesday 19

Vintage Littelfuse Advertisement

Littelfuse, October 1953 Radio-Electronics - RF CafeOptical illusions have always been a big attention-getter. Many companies have employed their intrigue to promote their products and/or services. This optical illusion was used by Littelfuse (not Littlefuse), a company founded in 1927 and still in business today, to draw attention to a full-page advertisement in a 1953 issue of Radio-Electronics magazine. More interesting than the illusions, though is the information presented is about how their proprietary glass-encased fuse design will always burn out in the center of the link, where it is visibly obvious. It might seem trivial, but having tested fuses that appeared to be good but tested bad, that is a great feature. Modern plastic-encased fuses with spade terminals like those found in automobiles have a similar feature that makes visual inspection very easy and unmistakable. In another Littelfuse ad, they educate the reader about how a fuse's amperage rating is not the amperage level at which it will blow...

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. 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...

Reducing Risk, Improving Quality of Military Radar Receivers

Reducing Risk, Improving Quality of Military Radar Receivers - RF Cafe"An industry-leading military radar receiver manufacturer needed to deliver radar receivers that met tough new customer specifications. To ensure a quality product, the manufacturer reviewed many aspects of its test strategy, focused on ensuring its radar receivers could meet the new specifications. Radar receiver sensitivity is critical for electronic warfare (EW) applications. A radar receiver that is outside specifications will fail to decipher signals properly from long distances. This is not an option in military applications. The aerospace and defense manufacturer needed to improve receiver sensitivity and the accuracy of its power level measurements in order to meet its design specifications and cost goals. Receiver sensitivity is defined as the minimum signal level that is intelligible..."

Dilbert Videos

Wally the Royal Engineer, Dilbert The Knack - RF Cafe Videos for EngineersSomehow I missed the "Royal Engineer" part of the engineering experience. In the first video, our hero Wally is evidently used to it, though. "The Knack" has become a classic amongst Dilbert fans, many of whom identify with his special gift. The last video is sort of a take-off of the 1993 Michael Douglas movie "Falling Down." Warning: Watching these clips from the Dilbert television show that ran from January 25, 1999 through July 25, 2000, may cause you to spend hours of valuable time viewing all the other clips that are available. RF Cafe cannot be held responsible for lost productivity...

The New Normal - Face Masks Forever

The New Normal - Face Masks Forever, Kirt's Cogitations #322 - RF CafeAbout a decade ago, photos began appearing on news websites showing Chinese citizens walking around wearing face masks in order to filter out the massive air pollution pouring from city factories and coal-fired electric power generation plants. Articles were written advising on the best types of face masks to use while visiting or working in China. The only topic about China competing for shock factor at the time was the rash of suicides at Foxconn as the poor soulless, hopeless workers who build our inexpensive electronics products jumped from upper factory windows and roofs. Since around March of this year, nearly every location in the United States and around the world is looking like China did for the entire last decade. A worldwide pandemic was declared because of a deadly virus which originated from the Wuhan area of China...

Tech Cryptoquip™

Tech Cryptoquip (tm King Features Syndicate) - RF CafeThe following technology-themed "Cryptoquip" appeared in the Erie, PA, newspaper on December 26, 2019. It is from King Features Syndicate and is likely covered by copyright. I attempted to find a webpage for it that I can link to, but with no success. King Features Syndicate publishes a huge number of my favorite comic strips. With a Cryptoquip, you try to decode a message by substituting letters for the ones presented. It is usually pretty easy after you have done a few. A clue is always provided for one letter. In this case it is F = P, so you substitute the letter P everywhere you see the letter F. The message is usually a form of pun (aka quip)...

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.

Tuesday 18

Highway Radar

November 1947 Radio Craft Cover - RF CafeRadar speed guns have been the bane of drivers - and the bounty of police department coffers - since the 1940s. The technology that helped the Allied Forces win World War II was exploited immediately thereafter by law enforcement in an effort to make the highways a safer place. Rather than relying on a police officer's learned estimation of a car or truck's speed, a certified radar unit was used by a trained operator. Prior to the advent of speed radar, a common method for determining a motorist's speed was to measure the time taken to travel between two points whose distance apart was known. The information was admissible in court, but was more vulnerable to a crafty prosecutor's interrogation. Radar removed that variable, although there probably have been cases where the accuracy of the radar unit was challenged in terms of electronics performance, false signal returns, adjustment for slant ranges, etc. The cover photo of this 1947 issues of Radio-Craft magazine shows a constable...

Femtosecond Streaking Makes Quick and Easy Light Measurements

Femtosecond Streaking Makes Quick and Easy Light Measurements"A new 'femtosecond streaking' technique has been used to directly measure oscillations in the electric fields of visible and infrared light. Developed by researchers in Canada and Germany, led by Aleksey Korobenko at the University of Ottawa, the method is a cheaper, faster and more practical version of the established technique of attosecond streaking. Through further improvements, the new technique could find use in high-speed electronics and studies of plasma dynamics. By determining the characteristics of coherent light fields, researchers can learn much about how light interacts with matter, and how it can be better manipulated on the shortest timescales. For visual and infrared frequencies, this can be done by visualizing how light's electric field evolves over time using attosecond streaking..."

LSI Gives Semiconductors a "Trip" - A Quiz

LSI Gives Semiconductors a "Trip", February 1970 Popular Electronics - RF CafeI have no idea why this "LSI Gives Semiconductors a 'Trip'" quiz from Popular Electronics magazine is titled what it is. LSI stands for "Large Scale Integration" and is generally applied to integrated circuits, not discrete components. The quiz's creator has come up with 17 questions, only the first of which has anything to do with LSI circuits. The other 16 are on topics like capacitor plate spacing, magnetorestrictive material, and coaxial cable. I realize that LSI attempts to minimize the number of external components necessary by absorbing them into the IC, but I'm just not sure what that has to do with whether a submarine can communicate via SHF while submerged.

One Hundred Years of Radio

One Hundred Years of Radio - RF CafeRadio Ink magazine still has copies of their commemorative "One Hundred Years of Radio" issue. Says their website: "Radio Ink is celebrating 100 years of radio with a coffee-table issue of Radio Ink Magazine. Pages and pages of radio executives commenting on how radio has been able to survive for 10 decades. Plus special columns from Randy Michaels, Art Vuolo, Publisher Deborah Parenti and others, and a special feature on KDKA. Get your copy before they run out."

Radio Signals to Venus

Radio Signals to Venus, June 1958 Radio-Electronics - RF CafeThat Hugo Gernsback was a profound and prolific visionary is obvious by anybody's estimation. Throughout the early and middle 20th century, the man both predicted and participated in as many technical creations as any of his contemporaries. Being a publisher of both science fiction and science fact books and magazines, Gernsback wrote of fantastic inventions ranging from weapons to medical equipment to space travel (and the vehicles that would shuttle mankind about in his quests). Just as Arthur C. Clarke's talents extended beyond sci-fi adventures to include devising a scheme for geosynchronous orbit satellite communications, Hugo Gernsback designed and sold many electronics experimenters' kits, instruments, components, and even proposed a method for determining the rotational period of cloud-covered Venus. Because of Venus' perpetual atmospheric shroud of sulfuric acid which is impenetrable by visible light, radar is needed to map the planet's surface and determine when a full rotation has occurred...

Please Visit Bittele Electronics in Appreciation of Their Support

Bittele Electronics PCB Fabrication - RF CafeSince 2003, Bittele Electronics has consistently provided low-volume, electronic contract manufacturing (ECM) and turnkey PCB assembly services. It specializes in board level turnkey PCB assembly for design engineers needing low volume or prototype multi-layer printed circuit boards. Free Passive Components: Bittele Electronics is taking one further step in its commitment of offering the best service to clients of its PCB assembly business. Bittele is now offering common passive components to its clients FREE of Charge.

Monday 17

Over-the-Horizon Communications - Bell Labs

Over-the-Horizon Communications, Bell Telephone Laboratories, October 1955 Radio & Television News - RF CafeOver-the-Horizon (OTH) radio signal transmission was a relatively new phenomenon when this advertisement by Bell Telephone Laboratories appeared in a 1955 issue of Radio & Television News magazine. It was a big year for OTH. The discovery and exploitation of it was originally the domain of Ham radio operators who were allocated the believed-to-be useless spectrum that supports it. However, once the government realized the important ramifications of OTH communications (radar, voice, video), military research organizations quickly initiated efforts to exploit it for national defense and security purposes, then classified much of the science. In this same year as this advertisement an article by Bell Labs about OTH technology entitled, "'Over the Horizon'" Transmission" appeared in Popular Electronics magazine...

Sky5® Front-End Module for Mid- and High-Band 3G, 4G, and 5G Mobile Apps

Skyworks Sky5® Front-End Module for Mid- and High-Band 3G, 4G, and 5G Mobile Applications - RF CafeSkyworks is pleased to introduce the SKY58085-11, a Mid- and High Band Front-End Module (FEM) supports 3G / 4G / 5G mobile devices and operates efficiently in 3G / 4G / 5G modes. The module has separate 3G / 4G / 5G PA blocks operating in the mid- and high bands, a silicon controller containing the MIPI® RFFE® interface, RF band switches, MB and HB antenna switches, bi-directional couplers, and integrated filters for Bands 1, 2, 3, 7, 34, 39, 40 and 41. RF I/O ports are internally matched to 50 ohms to minimize the need for external components. Extremely low leakage current maximizes device standby time. IC die and passive components are mounted on a multi-layer laminate substrate. The 62-pad LGA assembly, encapsulated...

Is It Necessary to Clean No-Clean Flux?

Is It Necessary to Clean No-Clean Flux? - RF CafeHaving hailed from the pre-no-clean-flux days, my habit is to always clean solder joints with isopropyl alcohol. Flux, at least the rosin type, is acidic works etching away the oxide layer that forms on metal surfaces and can prevent proper solder action between components. Failing to remove the flux residue leaves acid that can eat at the joint. This article by Asker Roy entitled, "Is It Necessary to Clean No-Clean Flux?" addresses whether no-clean flux should be cleaned under certain circumstances. He writes, "No-clean solder paste generally doesn't require cleaning. Assemblers find it more difficult to remove the flux residue that no-clean pastes leave behind, as compared to flux from other types of solder pastes. Cleaning such trace residue creates a problem, because their designs don't allow them to wash off easily ..."

Many Thanks to Centric RF for Their Continued Support!

Centric RF microwave components - RF CafeCentric RF is a company offering from stock various RF and Microwave coaxial components, including attenuators, adapters, cable assemblies, terminations, power dividers, and more. We believe in offering high performance parts from stock at a reasonable cost. Frequency ranges of 0-110 GHz at power levels from 0.5-500 watts are available off the shelf. Order today, ship today! Centric RF is currently looking for vendors to partner with them. Please visit Centric RF today.

Should You Go Into Engineering?

Should You Go Into Engineering?, November 1954 Air Trails - Airplanes and RocketsThe middle of the last century was a time ripe with opportunities for people with a penchant for innovation, experimentation, designing, and building high technology products. Aviation, aerospace, land and sea transportation, medicine, manufacturing, chemistry, physics, astronomy, communications, electronics, mechanics, nuclear technology, remote exploration of space and the sea, and many other realms were pushing forward the frontiers of knowledge (or pushing back the frontiers of ignorance, depending on your viewpoint) at an incredible rate. Both trade and hobby magazines often featured articles encouraging participation as technicians and engineers in a field related to hobby interests (Ham radio, model airplanes, boats, and cars, etc.). Air Trails magazine ran many such pieces, including this 1954 example...

Thanks Again for Windfreak Technologies' Continued Support!

Windfreak TechnologiesWindfreak Technologies designs, manufactures, tests and sells high value USB powered and controlled radio frequency products such as RF signal generators, RF synthesizers, RF power detectors, mixers, up / downconverters. Since the conception of WFT, we have introduced products that have been purchased by a wide range of customers, from hobbyists to education facilities to government agencies. Worldwide customers include Europe, Australia, and Asia. Please contact Windfreak today to learn how they might help you with your current project.

Sunday 15

November 15th Electronics Engineering Crossword Puzzle

Electronics Engineering Crossword Puzzle for November 15, 2020 - RF CafeFor the sake of avid cruciverbalists amongst us, each week I create a new crossword puzzle that has a theme related to engineering, mathematics, chemistry, physics, and other technical words. As with all RF Cafe crossword puzzles, this November 15th Electronics Engineering crossword puzzle 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. , movie star unless he/she was involved in a technical endeavor (e.g., Hedy Lamarr)...



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