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Exodus Advanced Communications Best in Class RF Amplifier SSPAs - RF Cafe

Publicity Means Sales!

Publicity Means Sales!, December 1947 Radio News - RF Cafe"If you have dark eyes and blonde hair. and are under 30, you're due for some easy squeezing. Milligan's Appliance Center, 84 Main Street, is giving every girl between 16 and 30 who has these striking features a newly patented orange squeezer, to introduce the new item ... Note: Any traces of recent peroxide rinse will disqualify applicants." That is advertising copy offered as an example effective promotional material in a 1947 edition of Radio News. My first reaction was to think how something like that would never fly today, but then I wasn't so sure. It seems there must be anti-discrimination laws in this "offend nobody" climate today...

Radio Training Association of America Advertisement

Radio Training Association of America Ad, June 1932 Radio-Craft - RF CafeImagine having a serviceman of any sort arrive at your house, fix your problem, and present you with a bill of $6 - parts included. He would walk away satisfied that he had done a good job and was well compensated for the work considering the effort invested in training and qualification. $6 in 1932, per the Bureau of Labor Statistics' Inflation Calculator is worth $135.97 in 2015 money - that's a cheap service call even in today's economy. Further, the $14 stated as a day's earnings is $317.26 in 2025, which equates to 50 (work weeks/year) x 5 (days/week) x $243.86 (/day) = $79,315 (/year) - not too shabby. Just between you and me, that's more than I'm currently making per year running RF Cafe...

Thanks to Aegis Power Systems for Continued Support!

Aegis Power Systems - RF CafeAegis Power Systems is a leading supplier of AC-DC and DC-DC power supplies for custom and special applications. Aegis has been designing and building highly reliable custom power supplies since 1995. They offer a complete line of switch mode power supplies and power converters for a variety of markets including defense, industrial, aircraft, VME, and telecom. Supports military, aircraft, EV, telecom, and embedded computing applications. Design and manufacture of custom power supply solutions to meet each customer's exacting specifications. Please visit Aegis Power Systems today. Manufactured in the USA.

Oscillator Quiz

Oscillator Quiz, November 1962 Popular Electronics - RF CafeOscillators were never my forte. My biggest exposure to oscillators was unintentional oscillations in amplifier circuits ;-( .  This Oscillator Quiz, published in the November 1962 issue of Popular Electronics magazine, would embarrass me if I attempted to complete it. Therefore, I will simply state that I highly regard your oscillator prowess if you do better than 50% on it. I guessed correctly at a couple of the more familiar circuits, but cannot even make an educated guess at most of them. Don't let the presence of vacuum tubes scare you off; mentally replace them with a FET and move on...

"Sayville Once More"

"Sayville Once More", May 1941 Radio-Craft - RF CafeThese letters represent an unfriendly exchange between The Electrical Experimenter editor Hugo Gernsback and Dr. K.G. Frank, of the Telefunken System of Wireless Technology, of Germany. Gernsback correctly accused Dr. Frank of engaging in espionage for Germany and against the United States of America, during World War I at a time we were not officially at war with the Axis powers. He was arrested and interred for the duration of the war for sending out "unneutral messages" from the broadcast station at Sayville, Long Island, New York. See "Radiobotage" in this month's (September 1941) editorial...

DIY Stratosphere Pico Balloon

DIY Stratosphere Pico Balloon - RF Cafe"There's an interesting development in amateur ballooning: using so-called superpressure balloons, which float high in the atmosphere indefinitely rather than simply going up and up and then popping like a normal weather balloon. Superpressure balloons can last for months and travel long distances, potentially circumnavigating the globe, all the while reporting their position. You might imagine that an undertaking like this would be immensely difficult and cost thousands of dollars. In fact, you can build and launch such a balloon for about the cost of a fancy dinner out. You just have to think small! That's why amateur balloonists call them pico balloons. The payload of a pico balloon is so light..."

Radar Engineering Crossword

Radar Engineering Crossword Puzzle for August 16, 2015 - RF CafeMany of the words in this week's crossword puzzle pertain to radar engineering. All the rest of the words are related to technology, engineering, science, mathematics, aeronautics, ham radio, chemistry, etc. There are no names of Hollywierd actors, shoe designers, or romance novel titles. I will be glad to create a special edition crossword for your newspaper, newsletter, etc. Enjoy...

Mac's Radio Service Shop: Safety in Servicing

Mac's Radio Service Shop: Safety in Servicing, January 1954 Radio & Television News - RF CafeIt's time to gather 'round for another story about fictional radio service shop owner Mac McGregor and his trusted sidekick technician, Barney. In this episode, an errantly wired bypass capacitor on a chassis from one of the old AC/DC radio sets caused Mac to get a 300-volt wakeup call when his hand brushed against it. After explaining the situation to Barney and apprising him of the danger it poses to an owner who unwittingly sticks his/her hand into the back of the cabinet, Mac lists a few other common dangers to watch for. Radios that ran on either AC or DC power were very common back in the early days because there were homes and businesses that had both type systems wired in to the premises - in part due to the famous battle between Thomas Edison's preferred DC electrical distribution system and Nikola Tesla's preferred AC electrical distribution system. Another reason for DC compatibility was that prior to the Rural Electrification Act of 1936, many...

Editorial: Radiobotage

Editorial: Radiobotage, May 1941 Radio-Craft - RF CafeAn incredibly glaring example of the famous admonishment* that those who ignore history are condemned to repeat it, Radio-Craft editor Hugo Gernsback wrote in May of 1941, a full half year before the United States of America officially entered World War II, about how current conditions regarding domestic commercial radio broadcast stations were likely being used by German agents to send coded messages to offshore vessels (ships, submarines, and aircraft). In example, he cited, amazingly, an article he himself published in 1915 in The Electrical Experimenter accusing Dr. K. G. Frank, of the German Telefunken company, of conducting spy operations from the Sayville, NY, station on Long Island...

Crystal Receiver with Transistor Amplifier

A Crystal Receiver with Transistor Amplifier, January 1950 Radio & Television News Article - RF CafeConsidering that not much more than a year before this article was written that the transistor had been invented, it is impressive that already Raytheon was producing a commercially available CK703 "crystal triode." That nomenclature was a natural extension of the preceding crystal diode already being widely adapted in circuit design. If you have wondered how the transistor schematic symbol came to be as it is, you will learn why here where the emitter and collector symbols actually both have arrows on the ends that contact the base, indicating the "point contact" physical arrangement of the semiconductor junctions. Shortly thereafter the arrow on the collector port was eliminated, primarily, I suppose to avoid confusion when the E, B, and C labels are not present...

2D Transistor Transforms Logic, Power Devices

2D Transistor Transforms Logic, Power Devices - RF Cafe"CDimension recently unveiled a technology that enables conventional semiconductor fabs to use ultra-thin semiconductor materials to manufacture vertically integrated arrays of extremely small, fast, and efficient "2D" transistors. It has the potential to change what's possible for both digital and power devices. According to the company, it's already helping several chipmakers explore how to apply their technology to produce digital and analog ICs that offer dramatically higher logic densities, operating speeds, and energy efficiency..."

Radio Service Data Sheets

Emerson Models 20A and 25A Radio Service Data Sheet, July 1933 Radio-Craft - RF CafeHere are three more Radio Service Data Sheets added to the online archive. As mentioned many times in the past, I post these for the benefit of hobbyists looking for information to assist in repairing or restoring vintage communication equipment. These particular radio models - Emerson Model 20A and 25A, Pilot Model B-2, General Electric Model K-40-A - were featured in a 1933 edition of Radio-Craft magazine...

Networks for Television

Networks for Television, November 1947 Radio News - RF CafeNationwide commercial television broadcasting companies wasted no time stringing coaxial cable and microwave towers from sea to shining sea once the NTSC format standard was adopted and manufacturers had spooled up production after World War II. Adoption of cable services was slow because a fee was involved, but once purely cable channels started being added the perceived value increase convinced consumers to open their wallets. Eventually cable eclipsed over-the-air broadcasts for all but extremely rural areas that were not serviced by cable. Along came satellite TV to take care of filling that void. Once a small, inexpensive, unobtrusive Ka-band antenna replaced the huge S-band backyard parabolic dishes and subscription prices dropped significantly, suburbanites and city dwellers picked it up. Soon, cable companies were feeling the pinch as their customer bases shrunk. Not ones to sit...

Oscilloscope Quiz

Oscilloscope Quiz, October 1961 Popular Electronics - RF CafeA lot of RF Cafe visitors might not be familiar with some of the electronic waveforms presented in this Oscilloscope Quiz by Popular Electronics magazine's ultimate quizmaster, Robert Balin. The shapes are recognizable to anyone who has done a lot of design, troubleshooting, testing, or alignments on analog circuits. Electronics repairmen were intimately familiar with these - and much more complex - waveforms. Modulation of the z-axis is especially cool as it varies the intensity of the waveform. I always roll my eyes when, back in the day, a laboratory or medical facility in movies or on TV had an oscilloscope display with a Lissajous pattern writhing on the display...

SpaceX Shifts Focus from Mars to Moon

SpaceX Shifts Focus from Mars to Moon - RF Cafe"SpaceX is putting its longstanding focus of sending humans to Mars on the backburner to prioritize establishing a settlement on the Moon, founder Elon Musk said Sunday. The South Africa-born billionaire's space company has found massive success as a NASA contractor, but critics have for years panned Musk's Mars colonization plans as overambitious. The move also puts Musk in alignment with U.S. President Trump's shift away from Mars. "For those unaware, SpaceX has already shifted focus to building a self-growing city on the Moon, as we can potentially achieve that in less than 10 years, whereas Mars would take 20+ years. Difficulties in reaching Mars include the fact that "it is only possible to travel to Mars when the planets align every 26 months..."

Hands That See: NY Institute for the Blind Prepares Students for Ham License

Hands That See: NY Institute for the Blind Prepares Students for Ham License, December 1947 Radio News - RF CafeLife for the blind has always been fraught with obstacles that we who can see will never be able to fully appreciate. Society has come a long way in accommodating the special needs of those with no or severely reduced eyesight. Recent news stories report of experiments with electronic implants that use implants set into the eye and couple somehow with the retina to send image information to the person's brain. While in no way close to being able to be called sight, it has at least allowed the guy or girl with training to detect and avoid obstacles based on changes in scenery shading. We are probably a century away from true bionic vision, incremental improvements will thankfully improve the lives of our thusly challenged brethren. This article from a 1947 edition of Radio News reports on efforts made by the New York Institute for the Educations of the Blind to make amateur radio...

New! everythingRF Magazine

everythingRF Magazine - RF CafeeverythingRF, a long-time supporter of this website, is now, in addition to publishing e-books, putting out an e-zine which provides some insightful content, interesting products and expert interviews within the RF & Microwave industry. Vol. 4, now available, includes articles on Next Gen Adjustable Q-Band Gain Equalizers, Earth to Orbit:The Important Role of Antennas in NTN, Benefits for Phased Array Systems Through SM Components, as well as product features, upcoming industry events, and more. Download it now.

Mac's Radio Service Shop: Barney Talks A.C.-D.C.

Mac's Radio Service Shop: Barney Talks A.C.-D.C., September 1949 Radio & Television News - RF CafeHave you ever heard of a "globar" resistor? They have been around since the early days of radio and were used, among other things, to protect vacuum tube heater elements from burning up due to high inrush current when first turned on. Globars have a negative temperature coefficient (NTC) of resistance so that, opposite of standard carbon and metal film type resistors, they exhibit a higher resistance when cold than when hot. Mac and Barney discuss their use in this episode of "Mac's Radio Service Shop." You might be more familiar with the name "thermistor" for such devices, but globars are unique elements in that their construction from non-inductive ceramic material makes them useful at high power levels and high frequencies. Globar appears to now be owned by Kanthal (aka Kanthal Globar). Interestingly, Keysight Technologies...

Transistors: Types & Techniques

Transistors: Types & Techniques, November 1962 Popular Electronics - RF CafeLouis Garner was the semiconductor guru for Popular Electronics magazine in the 1960s when he wrote this article attempting to demystify the proliferation of over 2,000 transistor types. He devised a "transistor tree," tracing evolution from the obsolete point-contact transistor - unstable with high gain but noisy - to advanced designs balancing cost, frequency, power, and reliability. It covers pnp and npn basics, then details processes: grown-junction (inexpensive, good high-frequency); meltback diffused (similar, better response); alloyed-junction (popular for power); surface-barrier family (SB, SBDT, MA, MADT; excellent high-frequency, low voltage); post-alloy-diffused...

Notable Quote: Benjamin Peirce

Notable Quote: Benjamin Peirce - RF Cafe"Gentlemen, ei*π + 1 = 0 is surely true, it is absolutely paradoxical; we cannot understand it, and we don't know what it means. But we have proved it, and therefore we know it must be truth." - Benjamin Peirce (not to be confused with Captain Benjamin Franklin "Hawkeye" Pierce), 19th century Harvard mathematician. ei*π + 1 = 0 i, BTW, is known as Euler's identity - engineers live by it.

Twisting Crystal Changes Electricity Flow

Twisting a Crystal at the Nanoscale Changes How Electricity Flows - RF Cafe"Scientists have shown that twisting a crystal at the nanoscale can turn it into a tiny, reversible diode, hinting at a new era of shape-engineered electronics. Researchers at the RIKEN Center for Emergent Matter Science, working with collaborators, have created a new technique for building three-dimensional nanoscale devices directly from single crystals. The approach uses a focused ion beam instrument to precisely carve materials at extremely small scales. Using this method, the team shaped tiny helical structures from a topological magnetic material made of cobalt, tin, and sulfur, known by its chemical formula Co3Sn2S2..."

Hitler Takes up Television

Hitler Takes Up Television, January 1935 Radio-Craft - RF CafeI am constantly amazed when reading stories about how easily Adolph Hitler rose to power in Germany by encouraging and exploiting resentment of his countrymen over being forced, among other concessions outlined in the Treaty of Versailles, to disarm militarily and make reparations for atrocities committed in World War I. Part of the Nazi (National Socialist) party success was extensive use of propaganda via print, radio, and the relatively new technology of television. Government exercised complete control over the mainstream media (i.e., not "underground") by dictating content that promoted the proclaimed virtues of Nazism and the Aryan race and the vices of just about every other form of government and race. At the height of Hitler's reign of terror during the Third Reich era, radio and television sets were only permitted to use crystals tuned to state-sponsored...

More About "Man-Made" Static 

More About "Man-Made" Static, May 1930 Radio-Craft - RF CafeManmade electrical noise (QRM) and natural electrical noise (QRN) has been the nemesis of communications - both wired and wireless - since the first signals were sent. While it is true that over the last century the amount of "background" noise has increased significantly, the ability of modern circuits to deal with (reject) it and/or accommodate (error correction) it has pretty much kept up with the advancement. You might be tempted to think that "back in the good old days" such problems did not exist, but operators were plagued by poorly designed and inadequately filtered transmitters as well as really deficient electrical service installation that spewed noise from transformers, inadequately grounded transmission lines, lousy connections...

Technical Headlines - RF Cafe

• FCC "Supercharge" Wi-Fi in 6 GHz Band

• Legacy Memory (DDR2, 3, 4) in Demand but Scarce

• 2026 is Year of 6G Slop

• FCC to Exempt Amateurs from Foreign Adversary Reporting

• Continuing Your Professional Education in 2026

• India Reaches 400M 5G Subscribers in 3 Years

Today in Science History - RF Cafe
Homepage Archives - RF Cafe

The RF Cafe Homepage Archive is a comprehensive collection of every item appearing daily on this website since 2008 - and many from earlier years. Many thousands of pages of unique content have been added since then.

Coils, Cores and Magnets

Coils, Cores and Magnets, November 1946 Radio-Craft - RF CafeThis very extensive article on iron-core inductors appeared in the November 1946 issue of Radio-Craft magazine. The first part, published the month prior in October, was an introductions to terms of inductance and magnetism, while this one deals with actual design curves and formulas. Iron core and air core inductors are the focus, and as you might guess (due to the use of iron cores) the frequency range addressed is audio and relatively low intermediate frequency (IF). In fact, separate treatment is given to coils operating at DC (direct current) and AC (alternating current). Back in the day, not only were most of the components inside a radio, television, record player, or other types of electronics devices serviceable (i.e., replaceable), but the components themselves were considered serviceable. That is, inductors, speaker coils, transformers, and even some capacitors were often repaired or modified to fix non-working circuits or to improve marginally functioning ones...

A Question of Semantics

A Question of Semantics, October 1970 Popular Electronics - RF CafeJust as you will never get everyone to agree on who was the first person to successfully fly a powered aircraft (Wright, Whitehead, Curtiss, etc.), there will never be a consensus on who invented the radio. Most people would probably agree that it was Guglielmo Marconi, but this author makes a case for none other than Thomas Edison. I don't recall ever hear anyone making that claim before, but before you dismiss the opinion, read on...

Wireless Engineering Themed Crossword for September 11th

Wireless Engineering Themed Crossword Puzzle for September 11th, 2022This custom Wireless Engineering themed Crossword Puzzle for September 11th, 2022, is brought to you by RF Cafe. All RF Cafe crossword puzzles are custom made by me, Kirt Blattenberger, and have only 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!

Radios Serviced by Observation

Radios Serviced by Observation, September 1945, Radio-Craft - RF CafeAnyone who has done a lot of electronics troubleshooting - especially on a wide variety of hardware - knows that proficiency depends on acquiring a 'feel' for how things ought to be. An oft-given example is that bank tellers and store clerks are taught to spot counterfeit bills not by showing them what all the different phony currency looks like, but what real money looks like. That way, anything that does not look familiar is readily apparent. The same philosophy has served technicians and engineers well since the beginning of electrical and electronic circuits. The more senses that can be drawn upon to facilitate troubleshooting, the more quickly you are likely to pinpoint the problem. Depending on the symptoms of the failure, sniffing the assembly for toasted or cracked components and looking for discolored areas is a good first step for catastrophic scenarios. Broken wires and failed solder joints are very common causes, as are partially plugged-in or contaminated...

Engineering & Science Crossword Puzzle for May 19

Engineering & Science Crossword Puzzle May 19, 2019 - RF CafeThis week's crossword puzzle will keep you busy for a while. Since 2000, I have been creating custom engineering- and science-themed crossword puzzles for the brain-exercising benefit and pleasure of RF Cafe visitors who are fellow cruciverbalists. The jury is out on whether or not this type of mental challenge helps keep your gray matter from atrophying in old age, but it certainly helps maintain your vocabulary and cognitive skills at all ages. 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...

Sylvania Electric Products

Sylvania Electric Products, February 1951 Radio-Electronics - RF CafeSylvania Electric Products was born out of Hygrade Sylvania Corporation in 1942, and continued until 1959 when it merged with General Telephone to form General Telephone and Electronics (GTE). That puts this 1951 promotion in Radio-Electronics magazine smack dab in the middle of their existence. Sylvania, like most major electronics products companies of the era, made vacuum tubes, CRTs, incandescent lamps, radios, even proximity fuses for warheads during World War II. In the 1960s and 70s, Sylvania produced semiconductor components and computers. Brick-and-mortar stores, whose primary competitors were mail-order businesses back then, were typically replete with sales promotions like this one featured in Radio-Electronics. Sylvania is now part of the LEDVANCE brand, owned by Chinese lighting company MLS. Is there any real American anything left anymore? Here is the Archive.org page on Sylvania's history, and here is an interesting piece on founder Frank Poor (who wasn't so poor following the company's immense success)...

Engineering Crossword Puzzle w/Weekly Headlines for July 8

RF Cafe Engineering Crossword Puzzle w/Weekly Headlines July 8, 2018At least 10 clues with an asterisk (*) in this technology-themed crossword puzzle are pulled from this past week's (7/2 - 7/6) "Tech Industry Headlines" column on the RF Cafe homepage. For the sake of all the avid cruciverbalists amongst us, each week I create a new technology-themed crossword puzzle using only words from my custom-created related to engineering, science, mathematics, chemistry, physics, astronomy, etc. You will never find among the words names of politicians, mountain ranges, exotic foods or plants, movie stars, or anything of the sort. You might, however, see someone or something in the exclusion list who or that is directly related to this puzzle's theme...

Wire Wrap: Bell Telephone Laboratories

Wire Wrap: Bell Telephone Laboratories, October 1953 Radio-Electronics - RF CafeAfter getting out of the U.S. Air Force in 1982, I was fortunate to get a job at the Oceanic Division of Westinghouse Electric Corporation in Annapolis, Maryland. Most of the guys who worked in the area with me were former electronics technicians from the armed forces. We spent most of our days (and often evenings) building small quantity specialty systems for the U.S. Navy. The facility was fairly small and was not set up for high volume production; that was the purview of the much larger operation based adjacent to the Baltimore / Washington International Airport (BWI), which built ground-based and airborne radar systems. Whilst there, I did a lot of wire-wrap assemblies that went into MIL-SPEC systems, primarily rack-mounted equipment in helicopters and aboard ships deploying towed sonar systems. As such, I received extensive training for performing soldering, wire-wrapping...

Electrical Shock: Fact and Fiction

Electrical Shock: Fact and Fiction, May 1959 Electronics World - RF Cafe"The Far Side" Doctors Poke Brain - RF CafeAny time I see an article that references causing limb movements by poking the brain with electrical signals, I think of the old The Far Side comic. Artist Gary Larson drew quite a few hilarious operating room scenarios. Electrocution is of course not a laughing matter - unless it happens to someone else and it is not serious and no harm is done. Then - and only then - can it be funny. I've laughed at myself many times after receiving a good jolt due to stupidity. Sometimes after such an experience I wonder how I never killed myself from getting zapped as the result of being too lazy to turn off a circuit breaker before servicing a light switch or receptacle. The sad thing is that I'll probably do it again some day...

Anaconda Copper Ad in the April 29, 1950 Saturday Evening Post

Anaconda Copper Advertisement in the April 29, 1950 Saturday Evening Post - RF CafeIt's not often that you will see a full-page ad promoting a particular element in the periodic table, but in 1950 that wasn't the case. This advertisement for Anaconda Copper Mining Company which appeared in a 1950 issue of The Saturday Evening Post magazine extolled the virtues of element number 29 - copper (Cu , from the Latin "cuprum"). Aluminum and iron were other popular topics of advertising. If you do a search on the history of Anaconda, which is today owned by the Atlantic Richfield Company (ARCO), what dominates is the harm done to workers and to the environment. The short video below is one of the less vicious reports on the company's operations in Butte, Montana and in Chile. COPPER... Time's Friendly Enemy Time and copper get along well together - because of one simple reason: Copper chooses to ignore time completely. For nature has given copper the great quality of almost eternal youth - the ability to resist the slow but steady ravages of the elements, for centuries if need be...

Radio-Electronics Puzzler

R-E Puzzler, January 1967 Radio-Electronics - RF CafeHere is a different kind of crossword puzzle. Called the "R-E Puzzler," it has only Across words and clues - no Downs. Its sort of a crossword puzzle with training wheels, or a crossword puzzle for the vertical word challenged. Actually, not having cross-linking Down words can make solving it a bit more difficult since only the one or two provided letters are available to assist in figuring out the correct word. Other variations of this sort of word grid has the provided letters spell out a word or phrase, but this one doesn't. Every word is related to electronics or electrical principles. Bon chance...

Electronics-Themed Comics

Electronics-Themed Comics, August 1946 Radio-Craft - RF CafeHopefully, you are winding down operations for the week and getting ready to celebrate Thanksgiving with a long weekend. This trio of electronics-themed comics from a 1946 issue of Radio-Craft magazine will help get you in a jovial spirit, regardless of whether or not you're getting the long weekend. I've mentioned many times that these comics make a good source of levity for adding to your presentations. As you might have guessed if you are familiar with Frank Beaven, he drew the top and bottom comics. He also drew the middle one. Two of these comics are part of his "Radio Term Illustrated" series, where magazine readers sent him suggestions for a theme that could serve, along with his drawing, as a sort of double entendre. Enjoy!

Determining Voltage Standing-Wave Ratios

Determining Voltage Standing-Wave Ratios, June 1954 Radio & Television News - RF CafePoor impedance matching between the source and load has been the cause of many poor performance issues ever since the wavelength of the transmitted signal became less than the length of the interconnecting line. A generally accepted rule of thumb is that when the line is more than about a tenth of the wavelength of the highest frequency, impedance matching is probably required lest standing waves cause problems. An impedance mismatch causes part - or maybe all - of the incident signal to be reflected back towards the source. That results in part of the signal not being transferred to the load, and the rest is dissipated as heat and/or radiated as an electromagnetic wave. In some circumstances the reflected signal can cause damage to the source because the reflected voltage can be much greater than the output circuit can withstand. VSWR is not just a concern for transmitters...

Looking Ahead/News Briefs

Looking Ahead/News Briefs, October 1968 Radio-Electronics - RF CafeSchemes for transmitting newspapers via airwaves and cable had already been around for a couple decades by the time this piece appeared in a 1968 issue of Radio-Electronics magazine. Large publishers like the New York Times, Atlanta Journal and Constitution, Los Angeles Times, Chicago Tribune, etc., wanted the ability to sell subscriptions to entities and individuals who desired time-sensitive information even more quickly than an overnight airline flight could provide a hard copy. The vision would ultimately need to wait for the advent of the Internet before widespread, affordable service would be available - primarily because the original vision of producing hard copies of entire newspapers at remote locations was (and still is) impractical. Color television was overtaking B&W as being dominant in households, and a lot of effort went into improving picture quality. A big problem was inconsistent hue and brightness between sets, even those of the same make and model. The IEEE and others convened committees to investigate and remedy the issue. Analog signals complicated the problems, but even today's LED and LCD displays show a huge variation between monitors

RF Cafe Engineering Crossword Puzzle w/Weekly Headlines

RF Cafe Engineering Crossword Puzzle w/Weekly Headlines February 4, 2018 - RF CafeAt least 10 clues with an asterisk (*) in this technology-themed crossword puzzle are pulled from this past week's (1/29 - 2/2) "Tech Industry Headlines" column on the RF Cafe homepage (see the Headline Archives page for help). A couple even include Super Bowl-related news. For the sake of all the avid cruciverbalists amongst us, each week I create a new technology-themed crossword puzzle using only words from my custom-created related to engineering, science, mathematics, chemistry, physics, astronomy, etc. Enjoy!...

Erie Technological Products

Erie Technological Products, October 18, 1965 Electronics Magazine - RF CafeErie Technological Products, located in my adopted hometown of Erie, Pennsylvania, was a re-branding of Erie Resistor Company as the concern had begun manufacturing a wide variety of discrete electronic devices - resistors, capacitors, feed-through filters, silicon rectifiers. The Erie Resistor complex on 12th Street in Erie occupies a huge amount of real estate on both sides of the road. The overhead foot bridge can be seen in this photo. The buildings have long been vacated and stand with many others as reminders of the thriving manufacturing center that Erie once was. We still have a good bit of manufacturing here, but nothing like back in the hey days of the last century...

Mathematics in Radio - Differential Calculus

Mathematics in Radio - Differential Calculus, September 1932 Radio News - RF CafeThis entry level introduction of differential calculus as it applies to electronic circuit analysis appeared way back in a 1932 edition of Radio News magazine. It was written by none other than Sir Isaac Newton himself (just kidding, of course). Author J.E. Smith created an extensive series of lessons that began with simple component and voltage supply descriptions and worked up through algebraic manipulations and on finally to calculus. I remember not being the best math student in high school (OK, one of the worst), but once I got an appreciation for the power of mathematics for analyzing electronics, mechanics, physics, and even economics, my motivation level soared to where I craved more of it and ended up receiving "As" in all my college math courses. That is truly an indication that while not everyone can excel at math, the proper environment can make a world of difference...

An Experiment with Gravity

An Experiment with Gravity, January 1970 Popular Electronics - RF CafeThis is pretty cool. If I owned a good receiver (which I don't), I would definitely give it a try. In 1970 when this Popular Electronics article was written, a lot of Hams were still using tube receivers so the recommendation to let the equipment warm up for several hours prior to making the fine frequency adjustments was good advice. Nowadays the warm-up time and stability of receivers should permit 30 minutes or so to suffice (even ovenized frequency references need time to stabilize when first powered up). Unless I missed it, the author does not explicitly state that the frequency change measured over time is due to gravity acting on the mass of the crystal reference, but I suspect that is his intention since part of the experiment involves disconnecting the antenna and shielding the receiver from outside interferers. Over a lunar month period (29.5 days) we experience a leap tide and a neap tide which maximizes and minimizes, respectively, the vector sum...

Exodus Advanced Communications Best in Class RF Amplifier SSPAs - RF Cafe