RF Cafe Software
About RF Cafe
1996 - 2016
BSEE - KB3UON
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 Internet was still largely an unknown entity at the time and not much was available in the form of WYSIWYG ...
All trademarks, copyrights, patents, and other rights of ownership to images and text used on the RF Cafe website are hereby acknowledged.
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There are 1,000s of Pages Indexed on RF Cafe !
These archive pages are provided in order to make it easier for you to find items that you remember seeing on the RF Cafe homepage. Of course probably the easiest way to find anything on the website is to use the "Search RF Cafe" box at the top of every page.
Homepage Archive Pages
2017: Jan |
Jun | Jul |
2016: Jan | Feb | Mar | Apr | May | Jun | Jul | Aug | Sep | Oct | Nov | Dec
2015: Jan | Feb | Mar | Apr | May | Jun | Jul | Aug | Sep | Oct | Nov | Dec
2014: Jan | Feb | Mar | Apr | May | Jun | Jul | Aug | Sep | Oct | Nov | Dec
2013: Jan | Feb | Mar | Apr | May | Jun | Jul | Aug | Sep | Oct | Nov | Dec
Here is page 2 of the April 2014 homepage archive
The Tube Family Tree Part I
For some inexplicable reason I went backwards on this three-part "Tube Family Tree" series that appeared in Popular Electronics. Author Louis Garner, Jr., starts out with the early history of vacuum tubes, beginning with Thomas Edison's incandescent light bulb and then quickly progresses to Lee de Forest's Audion amplifier tube, and on through the evolution of multi-grid vacuum tubes that are specially designed for low noise receiver front ends, high power transmitters, voltage and current regulators, video cameras, pulse forming networks, traveling wave tubes, and many other types. There is quite a bit of information and history contained in these three installments that will do a very nice job of introducing you...
Skyworks & Panasonic Form
Joint Venture for Filters
Skyworks Solutions, an innovator of high performance analog semiconductors enabling a broad range of end markets, today announced the creation of a joint venture with Panasonic Corporation, one of the largest electronic product manufacturers in the world, to design, develop and deliver high performance filters including surface acoustic wave (SAW) and temperature compensated (TC) SAW devices. At the core of the joint venture is Panasonic Filter Division's engineering and process talent , expertise in filter design and leading edge products as well as 412 fundamental filter patents...
Cool Vintage Tech Videos
from British Pathé
Newsreel archive British Pathé (named in deference of French moviemaker Charles Pathé) has uploaded its entire collection of 85,000 historic films, in high resolution, to its YouTube channel. Subjects span a pretty wide range, but fortunately there is a search function so you can narrow the field down easily to topics like "electronics," "radar," "telephone," "transmitter," "atomic," etc. If you also like historical accounts of automobiles, motorcycles, airplanes, medicine, trains, boats, chemistry, or just about any other subject, British Pathé probably has something related to that as well. Most videos are only a few minutes long, so they do not take much time to view. It seems that some of the videos on the pages of their website have been edited for brevity, but the YouTube versions...
AWR Intros V11 - First Majorbr>Software Release in 2014
AWR Corporation, the innovation leader in high-frequency EDA software, releases NI AWR Design Environment™ V11, its first major software release in 2014, which includes new features, enhancements, and user interface changes to Microwave Office®/Analog Office® circuit design software, Visual System Simulator™ (VSS) system design software, AXIEM® 3D planar electromagnetic (EM) software, and Analyst™ 3D finite element method (FEM) EM software...
Carl and Jerry:
Succoring a Soroban
Do you know what a soroban is? I have to admit ignorance prior to reading this 1963 "Carl and Jerry" adventure in Popular Electronics. As with many of these stories, real equipment, people, and companies were referenced; this time it was the Pastoriza Personal Analog Computer, a modular electronics system for calculating differential equations. The cost was around $300 (~$2,300 in c2014 money). Analog Devices bought the company from James Pastoriza in 1969. What does the Pastoriza computer have to do with the story, you might ask? Nothing, really; it was mentioned in a discussion Carl and Jerry had when accepting a calculating speed challenge from obnoxious dormitory mate...
for April 29, 2014
Microwave Circulator Design, 2nd Edition, by Douglas K. Linkhart. Circulator design has advanced significantly since the first edition of this book was published 25 years ago. The objective of this second edition is to present theory, information, and design procedures that will enable microwave engineers and technicians to design and build circulators successfully. This resource contains a discussion of the various units used in the circulator design computations, as well as covers the theory of operation. This book presents numerous applications, giving microwave engineers new ideas about how to solve problems using circulators. See RF Cafe Quiz #59.
FBN's Manufacturing Marvels
Features Res-net Microwave
Television's Manufacturing Marvels will soon shed some light on the business sector consisting of passive electronic components built for microwave & RF applications, and on Res-net Microwave, one of the very successful microwave component manufacturers in that sector. The 2-minute profile will air on the Fox Business Network on May 8th between 9:3-9:45pm ET. Manufacturing Marvels narrator John Criswell will describe and show some of Res-net's special manufacturing capabilities...
RF Cafe Questionnaire
Book Set Winner Selected!
Congratulations to winner Steve Gilbert, of Brecksville, Ohio! Steve's name was drawn form a pool of about 100 entrants. The results of the questionnaire will be summarized and posted later. Said Steve upon learning he had won, "All right, this is the first thing I've won since 1980 when I won five free lunches at Arby's on a radio contest for being the first to person to phone in and identify the mystery song... which happened to be 'Dead Skunk in the Middle of the Road' by Louden Wainwright III. One of my favorite hobbies is finding mistakes in
Notable Tech Quote
"I think high self-esteem is overrated. A little low self-esteem is actually quite good…Maybe you're not the best, so you should work a little harder." Also... "Stephen Hawking is getting a divorce. That's scary. If the smartest guy in the world can't figure out women, we're screwed." - Jay Leno
Engineering Career News
Jobs, So Why Are They in
‡ Engineering Jobs at
Walmart... Who'd Have
‡ Managers Beware: What
Toxic "Jane" or "Joe" Can
Do to Your Team
‡ Why Social Networks Are
‡ IEEE-USA Rolls out New
‡ New Hope for Enhancing
U.K. Skills: Apprenticeships
‡ Recruitment Gets Scientific
Early Google Glass?
"This must be the early prototype for Google Glass," was the first thing that came to mind when I saw this story in a 1962 edition of Popular Electronics? It is intended to allow 'future' astronauts to have improved situational awareness by providing means to look behind himself without needing to turn around, and to receive mission data via a miniature CRT embedded within the viewer. Voice communications is featured as well. Hughes Aircraft Company (nowadays just 'Hughes') might just want to consider assigning a handful of its highly paid attorneys to look into a patent infringement action based on the original content of its "Electrocular" headset...
NuWaves Awarded Contract for
RF Upconverter for Satellites
NuWaves Engineering, an international Radio Frequency (RF) and Microwave solutions provider, announced today that the company has been awarded a contract from a U.S. Department of Defense (DoD) contractor to rapidly develop a custom RF upconverter module for use in a government satellite application. The custom RF upconverter will not only translate an IF signal to an RF signal, but it will also provide power amplification in support of the government's mission...
Smith Chart Video Tutorials
Dr. Cynthia Furse (note Smith Chart earrings in her photo), a Professor of Electromagnetics at the University of Utah's Department of Electrical Engineering, has produced a very nice video series that covers a wide range of topics and techniques on the venerable Smith Chart. The ten videos begin with an introduction, progress through reflection coefficients, shorts and opens, impedance matching, a slot line example, and finally a summary. Dr. Furse rose to worldwide fame about a decade ago a least partially based on the colorful handmade quit she created with a Smith Chart pattern; it is an exquisite example of juxtapositioning...
Amateur Radio Crossword
Puzzle for April 27, 2014
This week's crossword puzzle has an amateur radio theme. Every word and clue is not specific to ham radio, but every word and clue is related to engineering, science, technology, math, chemistry, etc. If you want to exploit your knowledge of movie stars and fashion designers, try the NTY puzzle.
Novel Radio Items
Here are a few tidbits of breaking electronic communications news from 1940. "Mayday" had evidently recently been adopted as the preferred distress call rather than "SOS" or even "Help!" For some unknown reason a radio owner desperate to get his set working again dragged a potato across the top of a vacuum tube and it suddenly started receiving the local station. An employee of Edison Company of NYC devised a "storm detector" for warning of potential lightning strikes in the area (possibly akin to Franklin's Bells?). In other news, 'long life' vacuum tubes were announced that would last up to 4½ years, and some police departments were finally receiving portable radios. It was an exciting time!
Electric Paint Pen
You don't have to have a PhD in electrical engineering to make nutty drawings, but it helps if you do it using conductive ink and a 12 kV neon sign transformer. The ink came from the Bare Conductive™ company's Electric Paint product line that is supplied in a jar for brush application or in a pen format. Evidently conductive paint is a big deal because it was just back in February of this year (see "The Art of Technology") that I mentioned another Kickstarter project called Circuit Scribe that produced a similar product. Bare Conductive is in production with not just the aforementioned conductive ink media, but also peripheral products for use in experimentation, including the custom interface circuit board shown below. I doubt the Electric Paint is meant to be incorporated into commercial gadgets...
FEKO 2014 Student Design
Getting Brains into Gear with the FEKO Student Competition. The popular FEKO Student Competition is once again open to all under-graduates and post-graduates who work on a supervised project in electromagnetic engineering and make use of FEKO. This annual competition is an opportunity for students to showcase their work. There are some attractive prizes up for grabs – a state-of-the-art laptop computer or attendance to an industry related conference anywhere in the world...
The Good Articles
Just Keep Flowing In...
Some people like to complain about the rising world population and the stress it places on the environment and economy. The upside of more humanity is that there is an unprecedented amount of research and product design being performed by some really smart people - many of whom would have gone undiscovered in remote regions of the Earth if not for outreach programs. The current plethora of great new books and magazine articles is evidence of it, like the ones I have hyperlinked below...
α - QAM Is Rising: 1024QAM
Dr. H. Mohammed
β - Gaps in Return Planes
- Yes or No?, K. Wyatt
γ - Part Average Testing Finds
and Rejects Outlier ICs,
δ - New Ampere Won't Affect
M. Rowe <more>
AWR Webinar Antenna Design
for Advanced Wireless
AWR Corporation, the innovation leader in high-frequency EDA software, will sponsor the upcoming Microwave Journal Magazine technical education webinar, Practical Antenna Design for Advanced Wireless Products. The webinar will be presented by Henry Lau, CEO of Lexiwave Technology, a solution provider specializing in RF system and RFIC design for communication and consumer products. Antenna performance plays a critical role in determining the communication range and quality of service for wireless devices. This webinar offers participants technical insights...
The Rest of the Story... What
LinkedIn Did Not Provide Space
An article on the Forbes website titled "22 LinkedIn Secrets LinkedIn Won't Tell You" recommended in secret #19:
"Be personal. Your profile is not a resume or CV. Write as if you are having a conversation with someone. Inject your personality. Let people know your values and passions. In your summary, discuss what you do outside of work. You want people to want to know you."
Not wishing to offend author William Arruda by completely ignoring his advice, I set about writing in effect a short bio explaining (apologizing for?) my existence and how I got from 'there' to 'here.' That I got a bit carried away was made abundantly clear by LinkedIn's software informing me that I had just pasted in 2,236 more characters than they thought would be enough for any reasonable person. It's always the 'reasonable person' thing that bites me in the posterior...
Ooooh, I should have posted this story about 23 days ago, but better late than never. I meant to, but forgot. The story documents development of the "transistom" device back in the 1958 timeframe. Keep in mind that it was just a decade earlier that Mssrs. Bardeen, Brattain, and Shockley introduced the transistor amplifier to the world. The transistom was basically a 3-terminal transistor with two additional leads for a revolutionary power source built from radioisotopes of magnesium and manganese. In the day, school kids, including me, were handed blobs of liquid mercury to inspect and pass around in class, demonstrating how relatively ignorant we were about things we now consider to be extreme health hazards. Accordingly, encapsulating radioactive material in consumer devices...
RF Safe-Stop™ - Unintended
Survivalists have been encouraging people to buy vehicles that were manufactured prior to the time when electronic ignition systems and/or computer controls were added so that when "The Big One" hits, the EMP from a nuclear blast will not shut down their vehicles. In doing so, if you live through the event, you will at least still have serviceable transportation. Getting gasoline from a pumping station will be impossible since those computers will be dead, but there will be a lot of disabled vehicles sitting around with tanks full of gas for sale. Capitalizing on the vulnerability of modern cars and trucks - and even boats, motorcycles, and snowmobiles for that matter - to being stopped cold by a powerful electromagnetic field, military and law enforcement agencies are developing systems that simulate the results of a nuclear EMP event...
A New Tool for the Serviceman
You are taught early in your electronics career to be mindful of the tendency for measurement equipment to affect the circuit it is measuring, and therefore the indicated results. In the case of high frequency circuits, even minute amounts of capacitance and/or inductance can render results utterly unusable, but even in circuits operating down to D.C. the simple internal resistance of a meter can profoundly affect measurement accuracy. High impedance circuits are particularly vulnerable to such "loading" effects by test equipment. For example, consider a circuit being measured that has an impedance of 10 kΩ and the internal resistance of the VOM is 100 kΩ. If the open circuit "true" voltage level is 11 V, then voltage division effected by the 100 kΩ meter in series...
The Day CRUD Radio Died
RF Cafe visitor and Amateur Extra Lynn L. sent me a link to this article titled "The Day CRUD Radio Died," by Donald Kimberlin. Mr. Kimberlin tells a real-life tale of an effort to track down and shut down a pirate broadcast station in southern Florida. The perpetrator, as it turns out, was an overambitious teenager who decided to provide a bit of listening enjoyment for his friends and anyone else within radio range. The hero of the story is a good-natured FCC marshal who, in spite of having to fight with his agency's bureaucracy, managed to 'convince' the lad to abandon his post. You will enjoy this quick read. It is posted on the Broadcaster's Desktop Reference website.
Tesslor R-601S Vacuum Tube
AM/FM Radio w/BT 3.0 Mod
For all the time I invest in researching and writing about vintage radios of the vacuum tube variety, it is somewhat embarrassing to admit that I still do not have an operational set, although a Crosley 03CB console model is in the works now. I did, however, buy a Tesslor model R-601S AM/FM radio a couple years ago in order to be able to enjoy the warm orange glow of vacuum tubes while other projects were in the works. The R-601S is a nice mix of the old and the new in that while it uses vacuum tubes for the speaker preamp and output driver circuits, there is a state-of-the-art solid state receiver front-end and tuner. I did a write-up and video tour of the Tesslor R-601S radio in 2012. Last Fall (2013), Tesslor added Bluetooth 3.0 wireless connectivity capability to the R-601S and offered to update my radio...
Featured Productbr>ESD Work Station
Here is an item than can be worth it's weight in gold. At today's gold spot price of $1283/oz., this 12.8-ounce Eclipse 900-056 Field Service ESD Protection Kit would be worth $16,422. OK, maybe that's overstated, but depending on what type of equipment you happen to be working on, zapping an electronic component because you failed to exercise proper ESD protection measures could potentially (pun intended) cost that much. Silver closed at $19.39/oz., so maybe it is a bit more realistic as it makes this ESD work station worth $248. That's about the price of a replacement smartphone or midrange radio if you zap it while tinkering. Seriously, though, if you work on microelectronics without adequate ESD protection measures, you're asking for trouble. Even if you don't fry anything right away, you are likely to create the "walking wounded" scenario where failure is imminent in the future. $34 for this ESD work mat is cheap insurance.
RC Circuit Quiz
Having worked around resistors and capacitors for more than four decades comes in handy when presented with 'simple' quizzes like this one that appeared in a 1963 Popular Electronics dealing with RC circuits. Still, there is always some trepidation involved when being subject, even voluntarily, to a test of any sort, regardless of whether you are fairly confident that it will be a lead pipe cinch, a cake walk, child's play, so to speak. Even if nobody else will bear witness to your effort, you would feel like a real moron if you missed even one of those simple questions that anyone with your level of experience should get right without even having to think about it. Such is the irrational fear I have when taking these quizzes prior to posting them on RF Cafe. I have always been honest about the results...
Please Thank DongJin
Technology for Their Support
As a premier manufacturer of RF connectors, cable assemblies and RF components, including specialty non-magnetic connectors, Dongjin TI is highly recognized an RF industry leader in Korea. Our premium products offer a competitive price, on-time delivery and best quality in the industry. They have no minimum order size and 1-day delivery. Products are ISO9001, ISO14001, ROHS qualified, as required. VSWR reports are available on request.
Free Engineering Magazine
Wouldn't it be nice if you could get a free subscription to your favorite hunting, bicycling, or cooking magazine merely by demonstrating that you have a vested interest in the subject that advertisers can exploit? Don't be looking for a year's worth of Field & Stream, Road Bike, or Baking to arrive in your mailbox anytime soon, but you can, if you are qualified, received complimentary subscriptions to many of the big-time engineering magazines. Here are just a few of scores available.
Advantages of Outdoor
Both funny and ridiculous I thought as I read this article from a 1940 edition of National Radio News where author Julius Aceves, a consulting radio engineer, makes the case for not buying a newfangled, cheap radio that is supplied with a built-in antenna when using a good old-fashioned outdoor antenna is the better option. It's not that he doesn't have a valid point about the larger, obstruction-free outdoor antenna providing superior signal strength and a greater signal-to-noise ratio; it's that part of his argument is that in doing so you are denying the outdoor radio antenna companies revenue. That mindset is akin to telling people they should not buy notebook computers because...
MECA Electronics Ad
for the MTT-S Show (IMS2014)
MECA Electronics would appreciate your taking a few moments to take a look at their newest magazine advertisement that highlights products they will feature at IMS2014 in Booth #842.
Career News & Job Hunting
It's been a couple weeks since posting links to stories on job searching and career management. I should put an entry on my weekly calendar to do so. The stock market is way up so the economy - and therefore the job market, must be going smashingly well - right?
• IEEE ResumeLab
• Don't Give It All Away at
the Job Interview
• 4 Ways to Make the Most
of a Business Opportunity
• 3 Steps to Take If You Are
Rejected from Your Dream
• Newest Organized Labor
Group: Start-up Employees
Notable Tech Quote
"The problems of the world cannot possibly be solved by skeptics or cynics, whose horizons are limited by the obvious realities. We need men who can dream of things that never were, and ask why not." - President Kennedy's address to the Irish Parliament in June 1963, JFK Presidential Library
MegaRF Design Services
MegaRF Design, of Escondido, CA, is a relatively new startup engineering design and development service. Owner Steve Massey, with his many years of circuit and system experience, is currently consulting with major RF and microwave companies to provide engineering design services to develop products for the commercial communications and military marketplace. All levels of service are provided. He will work with you from conception to schematics to layout to physical products, and everything in-between. RF testing and PCB prototyping services are available to complement the consultant design services (see extensive list of in-house equipment and software). Please call Steve at 760-748-MEGA (6342) to learn more. "Let's go get it done!"
Wireless Crossword Puzzle
for April 20, 2014
I considered not bothering to create these custom engineering themed crossword puzzles anymore, but in checking the website statistics, I discovered that my collection of crosswords that began more than a decade ago has generated more than 58,000 page views just in the last year alone. Evidently there are people who are interested. Since I make each one new every week, it is easy for me to create a custom puzzle for your company, school, club, event, etc. Send me an email if you have a request.
MPN-13 GCA Radar Model by
USAF Tech Elbert Cook
Elbert submitted photos of his completed MPN-13 GCA model with a spiffy real-looking camouflage paint job! It includes both the maintenance trailer and the operations trailer, complete with ASR antenna, PAR antennas (az/el), VHF and UHF antennas, and navigation hazard lights. The "M" part of "MPN" stands for "mobile." As such, I and hundreds - maybe thousands - of USAF radar technicians have over the decades disassembled, transported, and reassembled these radars many times. My radar shop at Robins AFB, GA, participated in what were code-named "Healthy Strikes" two or three times each year, whereby a claxon in the barracks rudely awoke 5th Combat Communications Group members at around 5:00 am to signify the beginning of what would be about a week...
Walter Drake Releases Guide
to Thermoformed Packaging
Walter Drake, a thermoformed packaging manufacturer, has recently released the "Purchasers Guide to Thermoformed Packaging". The guide will assist buyers and specifiers in the correct selection of thermoformed packaging such as plastic clamshells, thermoformed trays and blister packs. Walter Drake designs and manufactures custom thermoformed plastic packaging in the form of clamshells, trays and blisters for the medical, pharmaceutical, electronic (ESD, static dissipative), consumer and industrial packaging applications.
Do You Need an Expert
to Sue an Expert?
This article by Bob Ambrogi, of IMS Expert Services, rhetorically asks the question of whether an 'expert' is required in order to sue another 'expert' because of his sworn testimony. In this particular case an expert was hired to help prove claims of wrongdoing by a neighboring industrial complex. Being declared qualified as an 'expert' varies from state to state, but it usually requires extensive documented professional experience, and/or an advanced college degree, and/or professional registration as a result of special testing. I, for example, would likely not qualify to serve as an expert witness in a trial. Like it or not - and many people believe it to be a form of acceptable payola...
ECM Announces Distribution
Agreement w/MECA Electronics
ECM announced a new authorized distribution agreement with MECA Electronics to supply the manufacturer's line of USA made rugged & reliable RF/microwave passive DC – 20 GHz microwave components and solutions globally. MECA serves all areas of the RF/Microwave industries including world class network providers. They have long been the "backbone" of high performance wired and air-interfaced networks such as in-building applications, satellite communications, radar, radio communications, telemetry applications, mobile radio, aviation and air traffic communications...
Carl & Jerry: Aiding an Instinct
By 1962, John T. Frye's techie troubleshooting teenagers Carl and Jerry had graduated from high school and were attending Parvoo University (PU?) as electrical engineering students. It was a natural progression. Unlike many of the company names and products - like the Delco DN278 transistor mentioned here - that appeared in the Popular Science series, the college's name is fictional. Maybe author Frye had a connection to Porvoo, Finland, and Anglicized the name. I ran "parvoo" through a couple online anagram solvers to see if it was a disguised name (which would be apropos for a detective story) and the closest it came to a real word is 'vaporo,' which is an Esperanto term...
When I first saw the title of this poem from a 1941 edition of National Radio News, I thought it was going to be a plea to amateur radio operators not to give up their hobby just because the government would eventually prohibit broadcasting during the World War II years. As it turns out, the poem predated that era and is instead a generic encouragement to the magazine's readers to press on regardless of obstacles. It did show up in the Christmas issue, so maybe it was simply a message in the spirit of peace on Earth and goodwill toward man. In these harsh years of the government fomenting division and class envy amongst its citizens, it's kind of hard to relate to such a gentle, kindly mindset, but indeed it did once exist in America. Anyway, I though it was worth reprinting here. "Don't Quit" is sort of a simpler version of Rudyard Kipling's famous poem of inspiration titled "If."
for Arduino Development
If you haven't yet heard about the Arduino single board computer (SBC) experimenter's platform, then either you have been in a coma or you are just now entering the tech world. Think of Arduino as the electronic version of the famous mechanical Erector Set that was popular beginning in the early 20th century. Or, consider it the "grown-up" version of Lego's computerized Mindstorms building sets. Per the official website, "Arduino is an open-source electronics prototyping platform based on flexible, easy-to-use hardware and software. It's intended for artists, designers, hobbyists and anyone interested in creating interactive objects or environments..."
!!! FREE SMA Finger Wrench !!!
Courtesy Bracke Mfg.
We now have a source for those much-sought-after plastic SMA finger wrenches! Bracke Mfg manager Lawrence P. sent me an email today saying that Bracke will be glad to mail anyone who requests them a sample of up to 5 of the SMA finger wrenches - what a guy! I'm guessing he saw the plea posted here on RF Cafe and on various forums for people looking desperately for the things. The SMA finger (thumb) wrench, known also by its Latin binomial nomenclature of 'digitus divellit,' is a rare breed of tool for the RF / microwave engineer, and appears to be indigenous to industry trade shows like MTT-S and European Microwave Conference...
Satellites and ET EM Waves
Prior to around 1960, the nature of electromagnetic radiation outside the Earth's atmosphere was entirely a matter of scientific conjecture. As is evidenced by this 1961 article, at the time it was still not known for certain whether electromagnetic energy outside the bands transmitted through the ionosphere existed for sure. There was of course no reason to believe that low frequency, long wavelength radio waves were not present along with the rest of the spectrum, but experiments needed to be developed that would launch satellites above the atmosphere to detect probable out-of-band signals and then re-transmit them on frequencies known to easily penetrate the 'ether.' Many failures occurred along the way, but persistence paid off...
Explaining Tuned Circuits
Fundamentals of resonant tank circuits has not changed since they were first investigated more than a century ago. This "After Class" tutorial that ran in the May 1961 edition of Popular Electronics is typical of the series where the author speaks as though he was giving an impromptu lesson to a gathering of students after the scheduled classroom period was over or, in this instance as though he was having a casual discussion with a friend who was perplexed by a particular electronics phenomenon. Figures and equations are often drawn by hand to augment the informal setting rather than being typeset. Here, "Larry" is amazed...