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KR Electronics (RF Filters) - RF Cafe

WH Correspondents Dinner Shooter Video

WH Correspondents Dinner Shooter Video - RF CafeHave you noticed that every time a shooting or other attack event occurs - especially pertaining to "R" targets - the quality of the video looks like something from the 1970s, or of a UFO sighting? Most private surveillance cameras in homes, cars, and businesses - even traffic cams - have resolution and full color so good you can distinguish faces and even identify brands of clothing, weapons, etc. This is a frame from the attempted assassination attempt this weekend at the White House Correspondents Dinner. The perp, a celebrated "Teacher of the Month" from California, rushed the security point with multiple weapons. Conceal carry, do training, and watch your six.

World's Most Powerful Radio Transmitter

World's Most Powerful Radio Transmitter, February 1954 Radio & Television News - RF CafeIn the early 1950s, the U.S. Navy built what was at the time the world's largest and most powerful radio broadcast transmitter station at the Jim Creek Naval Station on Wheeler Mountain in Washington state. Its 1.2 MW, 24.8-to-35 kHz VLF transmitter (call sign NLK) can reach anywhere in the world, even to submarines. A half wavelength at 24.8 kHz is 19,830 feet. Photos indicate that the transmitter is located in the middle of a dipole arrangement. "Catenary cables," if you are unfamiliar with the term, refers to the sagging shape assumed by both the antenna cables and the tower support cables. "Catenary" stems from the word "chain" since it is in the form...

Mac's Radio Service Shop: Carbon-Tet Can Kill

Mac's Radio Service Shop: Carbon-Tet Can Kill, February 1952 Radio & Television News - RF CafeCarbon tetrachloride (CCl4) was a common cleaning agent used commercially through about the early 1950s when it began receiving a lot of bad press due to a linkage to severe kidney damage from exposure even in vapor form. I notice that Mac mentions having read an article about the potential danger of "carbon-tet" in an edition of Radio & Television News magazine, not coincidentally the publication where the "Mac's Radio Service Shop" series appears. He also mentions a publication called International Projectionist, which included instructions for cleaning movie film with carbon tetrachloride, and had...

Transmission Line Systems for FM & Television Home Receivers

Transmission Line Systems for FM & Television Home Receivers - RF CafeIt is amazing to me how many times I read an article, whether in a vintage magazine like this 1947 issue of Radio News, or a current edition of QST, how when discussing maximum power transfer from a source to a load, the author states merely that the load impedance must equal the source impedance. The fact of the matter is that the source and load impedances must be the complex conjugates of each other in order for maximum power transfer to occur. That is to say that if the source has a complex impedance of R + jX, then the load must have a complex impedance of R - jX (and vice versa)...

War Assets Administration Advertisement

War Assets Administration Advertisement, February 1947 Radio News - RF CafeUnlike today when resources of all types seem to be endlessly available, during World War II countries needed to collect and recycle much in the way of metal, rubber, cloth, and other basic materials for re-purposing into products used in fighting the enemy. Media coverage of bottle, metal, and tire drives showed children pulling Radio Flyer wagons loaded to overflowing with such items gathered from trash piles and soliciting neighborhood residents for anything that could be spared. Raw materials were not the only type of items needed, however. "Use it up, Wear it out, Make it do, or Do without" was the slogan. Finished goods like electronic components - vacuum tubes, transmissions cable, transmitters and receivers, tuning capacitors, d'Arsonval meter movements, and other parts - were sorely needed by manufacturers both for building new equipment and for servicing damaged gear. After the war was won, the War Assets Administration...

The Great QSL Quarrel

The Great QSL Quarrel, October 1960 Electronics Illustrated - RF CafeAround the time when this "The Great QSL Quarrel" appeared in a 1960 issue of Electronics Illustrated magazine, there was a long-standing friction between amateur radio operators and shortwave listeners regarding the exchange of QSL confirmation cards. Far from mere paper, many hams view their custom-designed cards as valuable reflections of their personal rigs and efforts. Consequently, they often discard subpar listener cards that are illegible, aesthetically dull, or lacking meaningful data. To ensure their reports are actually welcomed, shortwave listeners are urged to adopt higher standards: utilizing professional printing or clear handwriting...

"Frequency" vs. "Amplitude" Modulation

"Frequency" vs. "Amplitude" Modulation, August 1935 Radio-Craft - RF CafeA momentous development that changed the field of radio communications warranted merely a half-page announcement in 1935 when frequency modulation inventor Edwin Armstrong had his article published in Radio-Craft magazine. It indisputably changed the world while causing poor Mr. Armstrong much grief while defending his right to the invention. Spread spectrum modulation / demodulation would be the next big communications advance that began with the frequency hopping (FHSS) scheme dreamed up by Hollywood actress Hedy Lamarr and pianist Antheil George during World War II. Direct sequence spread spectrum (DSSS) followed in the digital age, and since then I do not know of any fundamentally new communications technology in that time...

Flying Probe PCB Testing

San Francisco Circuits: Flying Probe Testing - RF CafeSince 2005, San Francisco Circuits has been a trusted U.S. provider of advanced PCB manufacturing and assembly solutions for R&D innovators, prime contractors, and integration experts. Flying Probe Testing (FPT) has long been a reliable method for validating PCB designs, particularly for prototypes and low volume production. Unlike traditional in circuit testing (ICT), which relies on custom built fixtures, flying probe systems use movable probes to test electrical connections directly, eliminating the need for dedicated hardware. Flying probe testing uses multiple programmable probes to contact pads...

Electronics-Themed Comics

Electronics-Themed Comics February 1947 Radio News - RF CafeThe February 1947 issue of Radio News only had two electronics-themed comics. Many months have up to half a dozen comics. Maybe the winter blues had set in with the magazine's illustrators. The first comic is a tad bit prescient in that it depicts a robber running past a television store and seeing a TV in the front display window showing a real-time video of the cop chasing him. That was way before there was a video surveillance camera on every street corner. I haven't discovered a vintage magazine yet with someone taking a "selfie." There is a growing list...

Schematics and Parts Lists for Vintage Vacuum Tube Radio Models

Emerson Models 501, 502, 504 Schematic & Parts List, November 1947 Radio News - RF CafeThese are the schematics and parts list for vintage Emerson vacuum tube radio models 501, 502, and 504; Crosley model 56TD-W; and Arvin model 140P as they appeared in the November 1947 issue of Radio News magazine. I scan and post these for the benefit of hobbyists and historians seeking such information. As time goes by, there is less and less likelihood that records of these relics from yesteryear's archives will be made available. As with all historical information, it takes someone with a personal interest in preserving the memories in order to fulfill the mission...

Test Equipment Teaser Crossword Puzzle

Crossword Puzzle - Test Equipment Teaser, March 1959 Radio & TV News - RF CafeJohn Comstock created many crossword puzzles for Radio & TV News magazine, and a couple others, in the 1950s and 1960s. This one titled "Test Equipment Teaser," appeared in the March 1959 issue. It is not a densely populated grid with complex intersections of crossing words (unlike the RF Cafe crossword puzzles, which do have them), but at least with this kind, all of the words and clues are directly related to electronics and technology (like RF Cafe crosswords). Anyway, it shouldn't take you too long to zip through this one. The only clue/word that might give you trouble is 32 Across. Enjoy...

Exodus Mission-Ready SSPAs for UAV Counter-UAS Systems

Exodus Mission-Ready SSPAs for UAV Counter-UAS Systems - RF CafeExodus Advanced Communications' representatives, in discussions during last month's EMV (Elektromagnetische Verträglichkeit) show in Cologne, had many attendees express interest in receiving an Exodus brochure covering our RF amplifier solutions for drone (UAS) applications. Exodus supports defense contractors with a family of RF amplifier modules optimized for UAV, drone, mobile, and fixed Counter-UAS platforms. At the center of this portfolio is the AMP10008, an ultra-lightweight solid-state RF amplifier module that demonstrates what is possible when SWaP is treated as a primary design driver rather than a compromise...

Resistor Trial by Test

Resistor Trial by Test, February 1954 Radio & Television News - RF CafeThe cover of this month's Radio & Television News magazine is part of the issue's story on performance testing of resistors. The author was an engineer for International Resistance Company (IRC), which is still in business as part of TT Electronics. The massive ovens were used for load-life testing to certify resistor products for both military and commercial uses. When required, humidity enclosures subjected resistors to increased levels to test for insulation breakdown at high voltage. As the article observes, since a 10-cent resistor can take down a multi-thousand system, it is important to guarantee every component's integrity...

Please Thank Werbel Microwave for Continued Support!

Werbel Microwave Passive RF Components - RF CafeWerbel Microwave is a manufacturer of RF directional and bidirectional couplers (6 dB to 50 dB) and RF power dividers / combiners (2- to 16-way) with select models operating up to 26.5 GHz and 100 W of CW power (3 kW peak). All are RoHS and REACH compliant and are designed and manufactured in our Whippany, NJ, location. Custom products and private label service available. Please take a couple minutes to visit their website and see how Werbel Microwave can help you today.

Espresso Engineering Workbook - Free!

Espresso Engineering Workbook™ for Excel - RF CafeRF Cafe's spreadsheet-based engineering and science calculator, Espresso Engineering Workbook™, is a collection of electrical engineering and physics calculators for commonly needed design and problem solving work. The filter calculators do not just amplitude, but also phase and group delay (hard to get outside of a big $$$ simulator). It is an excellent tool for engineers, technicians, hobbyists, and students. Equally excellent is that Espresso Engineering Workbook™ is provided at no cost, compliments of my generous sponsors. 49 worksheets to date...

U.S.A. Calling - Your Meters Go to War!

U.S.A. Calling - Your Meters Go to War!, December 1942 QST - RF CafeAlthough the Japanese attack on Pearl Harbor on December 7, 1941, was a complete surprise and shock to the nation, that fact that the United States would eventually be drawn officially into World War II was well known. The amateur radio community had begun talking about the potential impact on radio communications hobbyists earlier in the year, as evidenced by articles printed in QST and other magazines. Within a couple weeks of Congress declaring war, all unauthorized transmissions from Ham stations were terminated in order to prevent both intentionally and unintentionally conveyance of information that could proves useful by the enemy. Along with being a patriotic bunch that were eager to help defeat Axis powers, they also...

Electronics-Themed Comics

Electronics-Themed Comics January 1950 Radio & Television News - RF CafeHere, for your work-week enjoyment, are a half dozen electronics-themed comics that appeared in the January 1950 edition of Radio & Television News magazine. When is the last time you saw a comic in a technical magazine? I particularly like the one with the "green worm" displaying on the television. There is a list of other comics at the bottom of the page...

New 8-Prong "Glass-Metal" Tube

Just Announced - A New 8-Prong "Glass-Metal" Tube (754), August 1935 Radio-Craft - RF CafeIf this Radio-Craft magazine article is accurate, it was sometime around 1935 that the 8-pin glass-encased vacuum tube base came into existence. The glass-metal designation refers to these being glass enclosed equivalents to otherwise metal encased vacuum tubes. Evidently, the relatively new (and expensive) line of metal tubes sported 8-pin bases so these glass tube designs had to conform in order to be suitable substitutes...

Don't Fry That Ham!

Don't Fry That Ham!, October 1960 Electronics Illustrated - RF CafeIf some of the images in this issue of Electronics Illustrated magazine were made within the last couple years, I would swear they were AI-generated. Surely, there are not really people as stupid as those shown here... but, alas, there apparently are. These photos were published in 1960. The ARRL has always published recommended safety practices - particularly regarding high voltages from overhead power lines and lightning strikes. How anyone, like the guy in the first photo, could ever even considering standing on a ladder and sticking his arm between even the 240-volt house supply line from the utility pole - without even a current-limiting device like a fuse or circuit breaker inline - is beyond comprehension. Clearly, the antenna already installed...

Mac's Radio Service Shop: The Worm Turns - and Squirms

Mac's Radio Service Shop: The Worm Turns - And Squirms, January 1953 Radio & Television News - RF CafeThis episode of "Mac's Radio Service Shop" goes down a drastically different path than most, at least until the very end where a completely unrelated anecdote about interference with a remote garage door opener is told by Mac. Although the exact issues chanted by electronics technician cum repairman Barney Gallagher regarding many manufacturers' penchant for designing and selling unserviceable equipment is dated, the principle remains the same. We have all wished a designer had to service the product he/she has designed and sold to us...

Scientists Can't Seem to Stop Going Missing Under Mysterious Circumstances

Scientists Can't Seem to Stop Going Missing Under Mysterious Circumstances - RF Cafe"Ten U.S. researchers and scientists have reportedly died or disappeared over the past 33 months amid increasing speculation about the cause of some of the disappearances, according to news coverage. Steven Garcia, a 48-year-old government contractor who allegedly had top-level clearance at a key nuclear facility disappeared in August 2025 after reportedly leaving behind his phone, wallet and keys, taking a gun and leaving his home in New Mexico on foot, NewsNation reported Thursday. Moreover, retired Air Force Maj. Gen. William Neil McCasland similarly went missing on Feb. 27 after leaving his home in Albuquerque on foot, the outlet reported. Eight other well-known scientists and researchers..."

Radio & Radar Crossword Puzzle

Radio & Radar Crossword Puzzle for January 24, 2016 - RF CafeFor the sake of avid cruciverbalists amongst us, each week I create a new crossword puzzle. 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!

Bendix Models 636A, C, D Schematic & Parts List

Bendix Models 636A, C, D Schematic &amp; Parts List, February 1947 Radio News - RF CafeHere is Bendix Models 636A, C, D schematic and parts list as featured in a 1947 edition of Radio News magazine. No operational or alignment information was provided. The 636A is a tabletop radio using five vacuum tubes in the detector and amplifier stages, and a single vacuum tube rectifier in the power supply. Its shiny Bakelite cabinet sported an Art Deco style, which was popular back in the day. The images to the left are from a recent eBay listing, for $60, where the seller says it is in working condition. As mentioned many times in the past, I post these online for the benefit of hobbyists looking for information to assist in repairing or restoring vintage communication equipment...

Please Thank to Johanson Dielectrics for Support

Johanson Dielectrics - RF CafeJohanson Dielectrics has been a worldwide producer of high quality ceramic chip capacitors for over 60 years. We design and manufacture capacitors in a state-of-the-art facility in Camarillo, CA. Standard and high voltage SMT ceramic chip capacitors, as well as a variety of standard and custom high voltage & high capacitance value ceramic capacitors.

IGY - An 18 Month Report

International Geophysical Year (IGY) - An 18 Month Report, March 1959 Radio & TV News - RF CafeThe 1958-59 International Geophysical Year was an unprecedented eighteen-month global scientific initiative involving 30,000 participants from 66 nations who invested up to 1.5 billion dollars to study Earth's interior, oceans, and atmosphere. Utilizing military rockets and emerging satellite technology, researchers achieved major breakthroughs, most notably Dr. James Van Allen's discovery of the radiation belts surrounding Earth and enhanced understanding of ionospheric radio propagation, solar flares, and geomagnetism. While the project aimed to improve communications...

Erie Resistor Corporation Advertisement

Erie Resistor Corporation Advertisement, January 1952 Radio & Television News - RF CafeWhen I first saw an Erie Resistor Corporation advertisement in the December 1958 issue of Popular Electronics, I decided to research its history here in Erie, Pennsylvania, where I live. Click on that hyperlink if you are interested in what I discovered. This advertisement appeared in the January 1952 issue of Radio & Television News magazine, so I figured I'd post it as well...

Technical Headlines - RF Cafe

• Broadband Equipment Market Set for 2026 Rebound

• Foundry Revenues to Grow 24.8% YoY

• U.S. Manufacturing Sector Flexes Its Muscles

• Meta to Ax 10% of Workforce Being Replaced w/AI

• Middle East Conflict Rewiring Global Supply Chains

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.

Bell Labs - Voice of a Guided Missile

Bell Telephone Laboratories - Voice of a Guided Missile, September 1959 Radio-Electronics - RF CafeIn this 1959 Radio-Electronics magazine promo, Bell Telephone Laboratories showcased its advanced radio-inertial guidance system, a technological breakthrough enabling precise long-range missile flight. Developed for the Air Force's Ballistic Missile Division, this innovation proved its efficacy by guiding a Thor-Able nose cone to a precise target five thousand miles away, allowing for a successful aerial and maritime recovery. The system utilized a missile-borne transmitter to feed continuous data to ground-based radar and a Remington Rand Univac computer, which calculated real-time steering corrections. By keeping the primary command equipment on the ground...

Do You Know Your DC Circuits?

Do You Know Your DC Circuits?, May 1973 Popular Electronics - RF CafeA series of three articles appeared in 1973 issues of Popular Electronics that conducted a high-level review - or introduction if you've never seen it before - of DC circuit analysis. In this first installment, Professor Arthur Seidman, of the Pratt Institute, covers a variety of subjects starting with direct current (DC) circuit theory. Ideal current and voltage sources, units and notations, Ohm's law, Kirchhoff's law, resistors, capacitor and inductor charge and discharge curves, series and parallel circuits, power calculations, conductance, and other good stuff is covered. There is even (gasp) a bit of calculus presented...

Windfreak 5 MHz-8 GHz, 15-Band RF Filter

Windfreak Intros 5 MHz to 8 GHz, 15-Band, Switchable RF Filter - RF CafeWindfreak Technologies is proud to announces the availability of our FT108, an innovative programmable bidirectional filter bank spanning a frequency range of 5 MHz to 8 GHz in 15 bands. Band selection can be controlled through USB, UART or at high speeds through powerful triggering modes. Each unit is factory tested via network analyzer with unique data stored in the device to help with its use. Crossover frequencies are stored so the user can send a frequency command and the FT108 will utilizes Intelligent Band Selection logic to automatically toggle the optimal filter path based on minimum insertion loss. Readback of FT108 insertion loss at any frequency between crossover points allows for easy amplitude leveling...

Comics with an Electronics Theme

Comics with an Electronics Theme in Popular Electronics Magazine - RF CafeHere are a few more tech-themed comics from vintage editions (1962 and 1970) of Popular Electronics magazine. The first comic with the transistors and fuse is really clever, IMHO. It was one of the "Parts Talk" series. The other two are directed toward amateur radio operators, but you don't need to be one to appreciate the humor. There is a hyperlinked list at the bottom of the page of most of the other comics I've posted over the years. It's a shame that comics rarely appear in contemporary technical magazines - probably too afraid of offending someone...

Nitrogen Makes High Explosives for Modern War

Nitrogen Makes High Explosives for Modern War, March 23, 1942 Life - RF CafeIn the early days of America's official involvement in World War II (we were unofficially involved in supplying equipment and strategy much earlier), much effort was expended in educating the public on the implements and tactics of war. Doing so help engaged citizens and give them a sense of involvement. Motivating young men (primarily) to volunteer to go far from home to fight an enemy in places most had never heard of before was a tall order. Sure, a forced conscription was implemented (the country's first peacetime draft beginning September 16, 1940), but patriotic volunteers are generally preferred for leadership and long-term commitment to achieving victory. That's not to say draftees were not likely to turn out being leaders and career men. Interestingly, so many American men were volunteering for duty that a presidential order was issued in December of 1942 banning volunteer service; the government would be the sole determiner of who would be in the service. ...but I digress. This "Nitrogen Makes High Explosives for Modern War" article...

Hams Go Video

Hams Go Video, June 1959 Popular Electronics - RF CafeIronically, an RF Cafe visitor just within the last couple days wrote about possibly getting his Amateur radio license in order to permit live broadcasting of his kite-borne video camera system (known as "Kite Aerial Video" [KAV]), or Kite Aerial Photography [KAP]). Slow scan television SSTV has long been a popular facet of Ham radio since prior to broadband Internet connections; it was the only practical method available. Older equipment was large, heavy, power hungry, and relatively expensive, but today you can buy a much improved camera for a few bucks that transmits real-time via an unlicensed 2.4 GHz wireless link. That data stream can be recorded for later use of streamed real-time to the Internet. As with so many other things, easy availability takes some of the challenge out of it, but the world benefits from having all kinds of way-cool videos to watch...

Microwave Pulse Modulation

Microwave Pulse Modulation, April 1946 Radio News - RF CafeTry Googling "cyclodos" and "cyclophone" and see what you come up with. I found that Cyclodos is a German company which makes apparel from recycled inner tubes and tents (among other things), and cyclophone is a weird bicycle-mounted contraption for blasting sound while peddling down the street. In 1946 when this article appeared in Radio News magazine,, the terms cyclodos and cyclophone referred to modulator and demodulator tubes, respectively, for pulse-time modulation applications. Fortunately, the science of pulse modulation quickly evolved past such devices. This article goes into quite a lot of detail on the beginnings of pulse modulation techniques developed for radar systems during World War II. It is very informative without going into the gory details of equations that govern the theory...

Foreign Broadcast Intelligence Service

Foreign Broadcast Intelligence Service, January 1945 Radio News - RF CafeYou will not find the name Central Intelligence Agency (CIA) mentioned anywhere in this WWII era (1945 Radio News magazine) story reporting on the activities of the Foreign Broadcast Intelligence Service (FBIS), since the CIA was not formally established until 1947. FBIS became a branch of branch the CIA, however.  Per the CIA website "For nearly 70 years, the Foreign Broadcast Information Service (FBIS) monitored the world's airwaves and other news outlets, transcribing and translating selected contents into English and in the process creating a multi-million page historical archive of the global news media." Equally surprising is that the British Broadcasting Service (BBC) has a similar activity known as the Summary of World Broadcasts (SWB). Together, their operators attempted to monitor every radio transmission made worldwide in order to provide intelligence for the war effort. As with so many forms of technology during the war years, intelligence gathering capability grew rapidly and significantly. Listening to "chatter" amongst military personnel...

Mac's Service Shop: Chisel Blunters

Mac's Service Shop: Chisel Blunters - RF CafeThe dichotomy between the customer who is worried about the service shop owner ripping him off and the service shop owner who is worried about the customer ripping him off is an old one. Given how even normally honest people allow themselves a "white lie" here and there to consummate a business deal or pacify the whims of an acquaintance, it is understandable how such suspicions come to be. In this 1958 issue of Radio & TV News, Mac McGregor and trusty sidekick Barney Jameson discuss how to handle customers who imply the desire for or outright request (even demand) special consideration on repair services and/or replacement parts. The steadfast policy of Mac's Service Shop was "cash-only" - no exceptions. In the days before readily available credit cards and cash advances from ATMs, it was usually up to the business to extend and take the risk for credit. Often collecting on the promised funds consumed significant effort and on occasion resulted in failure...

Power Ratings & Intermodulation Tests

Power Ratings & Intermodulation Tests, November 1960 Electronics World - RF CafeAlthough this article discusses audio waveform measurements, the lesson learned applies equally well to any waveform frequency. In the RF realm, we are accustomed to injecting two sinewaves at equal amplitudes into a unit under test (UUT) and reading the relative output powers of the two input signals and the n-order intermodulation signals. It is usually a very simple test with simple to interpret results handily shown on the display of a spectrum analyzer. The task is made a bit more difficult when injecting signals of unequal strengths and especially when measuring in units of voltage as a viewed on an oscilloscope display. I dare say most of us need to do some head scratching and looking up of formulas to pull off such a measurement...

Thomas Edison in John Hancock Advertisement

Thomas Edison in John Hancock Advertisement from the April 29, 1950 The Saturday Evening Post - RF CafePresenting yourself or your company as being modeled after a person of great accomplishment has been a common promotional tactic for as long as there has been print media. The John Hancock chose in this issue of The Saturday Evening Post to suggest, albeit by an indirect approach, to elicit the admiration Americans had for Thomas Edison' lust for innovation and desire to make people's lives better in hopes that readers would associate Edison with the insurance company. While the juxtaposition is strained, I do like one line in particular, "He lured electricity into a bottle and taught it to glow with good cheer." This short tribute to on of the world's greatest engineers is worth your a few moments of your valuable time...

Cell Tower Deaths

Cell Tower Deaths (PBS Frontline) - RF CafeWhen a worker assembling cellphones in a plant in China hurls him/herself out of a window, it makes headlines. Like the human cost of extracting the minerals that go into making cellphone components, people yawn and write it off as the cost of progress. Among the many other dimensions of that cost is one that, until recently, received little attention - cell tower worker falls. According to a joint investigation by Frontline and ProPublica that was aired in May 2012, there is a well-established record of ill-equipped and ill-trained climbers who fall [pun intended] victim to low budget operations... and, to be honest, sometimes their own stupidity. Cell tower climbers experience 10x more on-the-job deaths as the average construction worker. That might seem logical and even expected given that you normally think of a construction worker as the guy banging nails in that new housing development down the road...

Federal Telephone and Radio Company

Federal Telephone and Radio Company Advertisement, January 1954 Radio & Television News - RF CafeCoaxial cable is the most familiar form of RF transmission line for most people these days. Up until 2009 when the U.S. switched to digital television (DTV), there were still a fairly large number of people who had the old 300 Ω twin lead cable running from roof-top antennas to TV sets. Over-the-air reception has petered off precipitously since then. Coaxial cable is undoubtedly more convenient and forgiving regarding routing since proximity to structures - particularly metallic components - is less sensitive than twin lead. Good quality 300 Ω twin lead cable (~70¢/foot today for 100') used to cost less than good quality 75 Ω RG-6 cable (~35¢/foot today for 100'), but just a couple decades ago when twin lead dominated, the opposite was true. What has not changed is the insertion loss of 300 Ω twin lead cable is typically around 2 dB at VHF TV channel frequencies (54-210 MHz), and 450 Ω ladder line (twin lead on steroids) is about 1/2 or less of that (see "Loss Figures for 300 Ohm Twin Line"). Insertion loss on RG-59 coaxial cable is around 4 dB/100' in the same band (RG-6 is ~3 dB/100', and RG-11 is ~2 dB/100')...

Survey of Transistor Development

Survey of Transistor Development: Part 3, November 1952 Radio News - RF CafeMr. B. N. Slade, of the Tube Department of Radio Corporation of America, wrote a series of articles on transistor development for three 1952 issues of Radio & Television News magazine. Consider that it was only four years earlier, a few days before Christmas, that Messrs. Bardeen, Brattain, and Shockley announced their game-changing invention of the point contact transistor. Already a plethora of commercial transistors were on the market for incorporation into new electronic products. At the time, germanium was still the semiconductor of choice, although silicon was gaining ground in laboratories. This article covers the three basic transistor circuit topologies of common emitter, common base, and common collector, which are analogous to vacuum tube circuits using common cathode, common grid, and common plate topologies, respectively. Operation up to around 200 MHz was obtainable...

Electronics Crossword Puzzle, April 1967 QST

Electronics Crossword Puzzle, April 1967 QST - RF CafeQST, the monthly publication of the American Radio Relay League (ARRL), occasionally ran a crossword puzzle with an electronics theme. This one appeared in the April 1967 edition. Unlike the weekly RF Cafe crossword puzzles, this one does have a few words that are not strictly technology and science themed. However, many of the clues and words require some familiarity with Ham radio subjects and lingo...

Crystal Diodes in Modern Electronics

Crystal Diodes in Modern Electronics, February 1952 Radio & Television News - RF CafeThis is part 5 in a series that began in the October 1951 issue of Radio & Television News magazine (see part 4). Previous articles dealt with crystal diodes in AM and FM radios, and this article shifts gears by moving into television applications. Crystal diodes were and are still used in frequency generation, envelope detection, frequency mixing, and AC signal rectification. Vacuum tubes could be used for the latter three applications but many physical issues such as size, weight, power consumption, and heat dissipation proved to be major drawbacks as designers strived to reduce the size of electronics assemblies, make them more energy efficient, lower the cost of manufacturing, increase reliability, and decrease weight. Demands for portability was the motivation for much of the work. Early crystal diodes could be noisy and fragile if not mounted carefully, but as will all technology, continual R&D has refined and improved crystals significantly...

Super Selectivity with Crystals

Super Selectivity with Crystals, July 1957 Radio & TV News - RF CafeThis Radio & TV News magazine article on crystal filters will probably be more useful to people responsible for maintenance on old RF systems than for new designs. The technology has come a long way since 1957 when it was published. Crystal filters were heralded as godsends as airwaves became more crowded and simple LC filters could not provide the required Q to prevent cross-channel interference. Of course the problem is many times worse today, but components are better now than then with low-cost integrated circuit front ends that handle a lot of the selectivity issues and SAW filters with better performance than many crystals...

The Silent War: Electronic Spying

The Silent War: Electronic Spying, April 20, 1964 Electronics Magazine - RF CafeAh, those were the good old days, when governments used their limited reconnaissance ability to spy on people, places, and things deemed to be a clear and present threat to the well-being of country. In 1964, during the height of the Cold War, collecting and interpreting communications data was still a very human-intensive chore, so assets were necessarily allocated based on highly strategic targets. Today, data collection collection, storage, and analysis is cheap and is done mostly unattended by humans until a red flag goes up. The possibility of a nuclear attack from the Union of Soviet Socialist Republics (U.S.S.R.) was a very real and even likely possibility. The strategic advantage of a first strike was immense, so it was to the world's advantage to monitor and react as quickly as possible. The Soviet Socialists liked to propagandize about being...

Homepage Archives for December 2023

Homepage Archives for December - RF CafeHomepage Archives for December 2023. Items on the RF Cafe homepage come and go at a pretty fast rate. In order to facilitate fast page loading, I keep the size reasonable - under a megabyte (ebay, Amazon, NY Times, etc., are multiple megabytes). New items are added at the top of the content area, and within a few days they shift off the bottom. If you recall seeing something on the homepage but now it is gone, fret not because many years I have maintained Homepage Archives.

KR Electronics (RF Filters) - RF Cafe