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Anritsu MA25211A P25 Radio Auto Test & Alignment System - RF Cafe Website

A Radioman's Wife Puts in a Good Word

A Radioman's Wife Puts in a Good Word, June 1951 Radio-Electronics - RF Cafe WebsiteIn the days before people were so easily offended by light-hearted poking, it was not uncommon to find magazine articles written by the wives of hobbyist husbands lamenting the habits and proclivities of their matrimonial mates. Over the years I have read many such treatises in model and full-scale airplane, electronics, and Ham radio publications. As with "A Radioman's Wife Puts in a Good Word" from a 1951 issue of Radio-Electronics magazine, they typically start by expressing frustration of having lost their once-doting husbands to alternative loves in the form of hobbies (I once saw a boat named "The Other Woman"). Determined to win back the devotion of their sweethearts, they...

Lamp Bulb Resistors

Lamp Bulb Resistors, April 1947 Radio-Craft - RF Cafe WebsiteMost people who have been in the electronics world for a while know that neon light bulbs* used to be commonly employed as a "pert-near" voltage regulator reference of between 55 and 65 volts, depending on the type. The familiar NE-2 has a turn-on voltage of 65 Vac (90 Vdc), for instance, and the voltage across the terminals remains there with little change regardless of the current through the bulb - a lot like a Zener diode. Neon bulbs are also used as non-invasive RF power detectors. Most people probably do not know, however, that incandescent bulbs also have properties that make them useful for purposes other than just lighting up a dark space. Incandescent light bulbs have...

ABCD-, s-, h-, T,- Y- Z-Parameter Conversions©

Espresso Engineering Workbook: ABCD-, S-, h-, T-, Y-, Z-Parameter Matrix Conversions - RF Cafe WebsiteThis newest edition to RF Cafe's *FREE* Espresso Engineering Workbook was a major bit of work. The ABCD-, s-, h-, T,- Y- Z- Parameter Conversions worksheet will convert a
2-port matrix of any of those types of matrices into the equivalent of all the others. Enter the real and imaginary parts and click the appropriate button. I do not know of any similar FREE conversion facility. True, the vast majority of visitors will never need to perform such conversions, but for those who do, well, here you are. My first exploit with them was way back around 1990 when writing a DOS program to do a cascade calculation of components whose s-parameters were known, but needed to be converted to an ABCD matrix for simpler calculation...

Radar & Radio Crossword Puzzle

Radar & Radio Crossword Puzzle May 10, 2020 - RF Cafe WebsiteSince 2000 - that's 20 years - I have been creating custom technology-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 village in the Andes mountains. You might, however, encounter the name of a movie star like Hedy Lamarr or a geographical location like Tunguska...

The Saga of the Vacuum Tube - Part 14

The Saga of the Vacuum Tube, November 1944 Radio News - RF Cafe WebsiteHere is Part 14 of a series entitled "The Saga of the Vacuum Tube," by Gerlad Tyne, that appeared in Radio News magazine in 1944. Part 1 was printed in March 1943, and Part 22, the final chapter, was published in April 1946. It could have been a stand-alone book. If I manage to be able to buy issues with some of the other parts, those will be posted as well. You might be aware of the origins of the amplifying vacuum tubes, beginning with the accomplishments of Dr. de Forest and his Audion. As with most new technologies, progress moved very rapidly once other researchers glommed on to the concept. Here, Mr. Tyne discusses the development of the "Kenotron," "Pliotron"...

Mac's Service Shop: Electrostatics at Work

Mac's Service Shop: Electrostatics at Work, February 1973 Popular Electronics - RF Cafe WebsiteElectronics wizard, repairman, and experimenter extraordinaire Mac McGregor, as sort of alter ego of author John T. Frye, provides a brief lesson on electrostatics for his repair shop apprentice wing man Barney (I don't think his last name was ever mentioned). In this 1973 Popular Electronics magazine article, Mac had built two types of electroscopes - one using a pair of pith balls suspended from silk strings and another that was a cobbled-together version of a gold leaf electroscope. His motive was two-fold. First and foremost was to accommodate his own interest in electrostatics, and second to hopefully engender enough curiosity in Barney to cause him to do a dive into science books...

A Brief History of Citizens Band Radio

A Brief History of Citizens Band Radio© - RF Cafe WebsiteCitizens Band Radio (CB) in the United States grew out of the post-World War II idea that ordinary citizens, small businesses, farmers, contractors, hunters, motorists, and families should have access to short-range two-way radio without the technical qualifications required for amateur radio. The Federal Communications Commission created the Citizens Radio Service in the 1940s, initially in the UHF region, but CB became culturally important only after the FCC opened the 27 MHz "11-meter" band to Class D Citizens Radio in 1958. That band, 26.965 MHz to 27.405 MHz today, is what most Americans mean by "CB radio.” CB was originally licensed. Users paid for an FCC license...

The Taylor "Super-Modulation" Principle (part 2)

The Taylor Super-Modulation Principle, October 1948 Radio & Television News - RF Cafe WebsiteRobert Taylor, along with inventing the concept of "super-modulation," also coined the new communications term "Intelligence Transmission Efficiency." It refers in part to the ratio of power in the intended sideband relative to power in the at least partially suppressed other sideband and carrier. Admittedly, I have not read this material enough to fully comprehend the concept of super-modulation, but at least based on the Fig. 1 waveform, there seems to be an element that adds a DC bias to the detected signal due to a nonsymmetrical (about 0 Vdc) transmitter modulation by pumping more power into the positive peaks. I'm happy to be corrected by any knowledgeable reader. For that matter...

The Taylor "Super-Modulation" Principle (part 1)

The Taylor Super-Modulation Principle, September 1948 Radio & Television News - RF Cafe WebsiteRobert Taylor claims - without contention from what I can find - to have invented the concept of "super-modulation," whereby the normal "splatter" created by greater than 100% amplitude modulation (AM) can be mitigated through use of specialized circuits. As with many paradigm-changing discoveries, much was made of super-modulation in the late 1940s through early 1950s, and then it pretty much dropped off the charts. The cause might have been that the sophistication of circuitry needed to keep everything tuned and tracking properly to prevent harmonic and sideband was deemed not worth the trouble once frequency modulation (FM) came on the scene. FM quickly gained...

Home TV Via Satellite

Home TV Via Satellite, May 1966 Electronics World - RF Cafe WebsiteIt would be more than a decade after the publishing of this article before the first direct-to-home satellite television broadcasts would be a reality, so it shows how long plans were being made for such systems. Rural landscapes are still peppered with the large vestigial C-band (~4 GHz) satellite dishes, many with faded eyeballs and other clever (and ugly) artwork on them. Before coaxial cable was strung beyond suburbs, country dwellers who either could not pull in over-the-air broadcasts from downtown locations or just wanted more viewing options paid dearly for satellite service. Equipment and installation costs on early systems could run into the $30k realm. Today's satellite TV systems use...

Mac's Radio Service Shop: Telephone Pickups and Other Subjects

Mac's Radio Service Shop: Telephone Pickups and Other Subjects, April 1954 Radio & Televsion News - RF Cafe WebsiteAt least in the U.S., laws regarding the recording of telephone conversations seem to be constantly changing and vary from state to state. Violation penalties - including imprisonment - can be severe in both cases. Some states require that all parties in the conversation be apprised of the recording, while others only require that at least one party (obviously the one doing the recording) be aware of it. As mentioned in this 1954 "Macs Radio Service Shop" story, some areas require that an audible "beep" be sounded at regular intervals while recording is occurring. With the ubiquitous use of smartphones featuring built-in recording capabilities, opportunities for recording and being recorded are constant...

Electro-Voice Microphones Advertisement

Electro-Voice Microphones Advertisement, February 1943 QST - RF Cafe WebsiteHere is an advertisement for Electro-Voice Manufacturing Company microphones that I scanned from page 101 of my copy of the February 1943 QST magazine. As with many companies during the World War II era, this one's theme is the service their products are providing to America's servicemen. Per the ad: If you were receiving radio messages from men in the midst of ear­splitting battle noises, you'd hear crisp speech undistorted by background sound effects. Electro-Voice Microphones, in military service, are helping to make it possible. Similar microphones, designed to achieve such results, will be available for specific commercial applications ... after our wartime job is done...

Voltage Standing Wave Ratio (VSWR)

Voltage Standing Wave Ratio (VSWR) - Its History, Meaning, and Calculation© - RF Cafe WebsiteVoltage standing wave ratio (VSWR), often shortened to SWR in radio work, is a measure of how well a load impedance is matched to a transmission line. It is defined as the ratio of the maximum RF voltage to the minimum RF voltage along a transmission line when forward and reflected waves interfere: VSWR = Vmax / Vmin = (1 + |Γ|) / (1 - |Γ|), where Γ, the reflection coefficient, is the complex ratio of reflected voltage wave to incident voltage wave. A perfect match has Γ = 0 and VSWR = 1:1. An open circuit or short circuit has |Γ| = 1 and VSWR is infinite. In practical RF systems, VSWR is a convenient scalar indication of mismatch, but it does not by itself show...

G-String Transmission and Helical Wave Coils

G-String Transmission and Helical Wave Coils, June 1951 Radio-Electronics - RF Cafe WebsiteWho says engineers and scientists have no sense of humor? This is not an April Fools joke or an attempt to punk you into reading the story. An Internet browser with strict parental control settings enabled might even prevent this page from even being displayed. In actuality, the term "G-String Transmission Line" was so dubbed by its inventor, Dr. George Goubau, as a tribute to his own name - both first and last. Out of an abundance of caution, I reference the Library of Congress' "G-String" entry for the good doctor and the device's legitimacy. A drawing similar to Fig. 1 in this 1951 issue of Radio-Electronics magazine can be seen on the chalkboard behind Dr. Goubau in the LoC...

Coming "Secret" Weapons - Sound Familiar? 

Coming "Secret" Weapons, November 1944 Radio-Craft - RF Cafe WebsiteUsually, when I read about yet another launching of rockets from Gaza into Israel, what comes to mind is the barrage of V1 Buzz Bombs and ultimately the V2 rockets that Germany terrorized London with during World War II. Although overall not very effective individually, they did cause brief spells of horror for the localized group of people that were affected through maiming, killing, or property destruction. The difference between the Nazi's weapons and Hamas' weapons is that the Germans didn't depend on other terrorist entities to supply them with their weapons of destruction; they were brilliant people who had evil intentions of world domination. Hugo Gernsback writes...

Electronics Company Foreign Acquisitions Quiz

Quiz #84: Electronics Company Foreign Acquisitions - RF Cafe WebsiteThe 20th Century American electronics industry produced some of the most influential companies in technological history, from the laboratories that invented the transistor to the factories that put televisions in every American home. Yet by the end of the century, many of these iconic names had passed into foreign ownership through a series of acquisitions driven by globalization, shifting competitive dynamics, and changing corporate strategies. Finnish, South Korean, French, Dutch, German, Chinese, Japanese, and other international buyers acquired what had once been pillars of American innovation. Bell Laboratories, RCA, Zenith, Magnavox, Sylvania, IBM's PC division...

Sangamo Electric Company Capacitors

Sangamo Electric Company, April 1954 Radio & Televsion News - RF Cafe WebsiteSangamo Electric Company was a "heap" big name in capacitors in the realm in the middle of the last century. The company always featured an American Indian in its electronics magazine advertisements, and usually also included some form of "indian-ese" statements as part of the sales pitch. Of course such marketing schemes would be vehemently raided and those responsible figuratively "scalped," if you will pardon the gratuitous expressions. As with using names like the Washington Redskins, the Atlanta Braves, the Chicago Blackhawks, and the Cleveland Indians to appropriate and celebrate the bravery and might of the named peoples, Sangamo implied quality, durability, and reliability...

All Channel Antenna Corporation

All Channel Antenna Corp., April 1954 Radio & Televsion News - RF Cafe WebsitePhased vertical stacks of two or more antennas were fairly common in the television realm - especially once color broadcasts became more dominant in the 1950s. Up to 3 dB per additional antenna is possible, but due to various non-ideal physical parameters (summed phase angle, imperfect antenna geometry, etc.), realized gain is typically in the 2.5 to 2.8 dB range. Higher signal to noise ratios were needed to guarantee good color separation with the National Television System Committee (NTSC) and stereo channel audio separation with the advent of Multichannel Television Sound (MTS). As you might expect, companies appeared claiming to have invented physics-defying antennas...

A Homebrew Soldering Gun

A Homebrew Soldering Gun, August 1947 Radio-Craft - RF Cafe WebsiteWe take a lot for granted these days with the seemingly unlimited availability of cheap stuff of all kinds - some of it complete junk and other of it pretty darn good. That goes for electronics components and complete products and test equipment, tools, automobiles, appliances, and utensils, clothing, medical equipment - you name it. Something as simple as a pistol-type soldering gun can be purchased at just about any hardware or home store, and at a price that when adjusted back to equivalent money in the 1940s would be amazingly cheap even then. For instance a Weller Soldering Gun kit from Lowes sells for $39.48 today (less when on sale), which would have been $3.44 in 1947

Today in Science History - RF Cafe Website
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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.

 

Southern California Amateurs Rise to Earthquake Emergency

Southern California Amateurs Rise to Earthquake Emergency, May 1933 QST - RF Cafe WebsiteThis could be a headline for today, tomorrow, or from 89 years ago when this article appeared in QST magazine. It was the latter, following the magnitude 6.4 earthquake that hit the Long Beach, California region. Per Wikipedia, "An estimated $40M worth of property damage resulted, and between 115 and 120 people died. Many of these fatalities occurred as people ran out of buildings and were hit by falling debris." That paled, though, in comparison to the magnitude 7.8 San Francisco earthquake in 1906, where massive destruction occurred and upwards of 3,000 people died. As usual, radio amateurs were some of the first emergency responders...

RCA Cunningham Radiotron Tubes

RCA Cunningham Radiotron Ad, July 1934 Radio News and the Short-Wave - RF Cafe WebsiteBack in the early days of radio - and then later television - companies used big-name media personalities to promote their wares. To a lesser extent some of that happens today as well. Advertisements like this one for RCA's Radiotron vacuum tubes appearing in a 1934 issue of Radio News magazine is typical of what you would have seen in the era. In it, none other than Bing Crosby was joined by a trendily dressed woman who was rejoicing in her decision to buy a new radio that contained those newfangled "Micro-Sensitive" receiver tubes. Radio was considered a mystical entity by most people, and in 1934 there were still many households that did not yet host a...

RF Cafe Quiz #16: Antennas

RF Cafe Quiz #16: AntennasAll RF Cafe Quizzes make great fodder for employment interviews for technicians or engineers - particularly those who are fresh out of school or are relatively new to the work world. Come to think of it, they would make equally excellent study material for the same persons who are going to be interviewed for a job. The subject of Quiz #16 is Antennas. You don't need to be an antenna expert to score well, but if you do or plan to work with antennas and cannot answer a question like, "What does dBi, the most often used unit for antenna gain (or directivity), stand for?," then maybe it is time for some review...

Playback Preamp for Stereo Tapes

Playback Preamp for Stereo Tapes, April 1958 Radio-Electronics - RF Cafe WebsiteHmmmm.... at the time I marked this stereo tape playback preamp project for posting I must have had a really good reason for it, but now I can't recall what that really good reason was. Maybe it was simply to mark the point in time when stereophonic electronic equipment was just beginning to be mainstream. Oh well, somebody somewhere will do a Google search on the topic someday and will be elated to find this. Besides, even though the use of vacuum tubes and magnetic tape is way outdated, there is a discussion of hi-fi audio that is still relevant. The article appeared in a 1958 issue of Radio-Electronics magazine. Thanks for your indulgence...

The Pest - Radio Repair

The Pest, July 1952 Radio-Electronics - RF Cafe WebsiteWhile reading through these vintage electronics magazines, I often wish I could have lived in the era and owned an electronics repair shop. Radios, televisions, record players, tape recorders, amplifiers, etc., were very serviceable with plug-in vacuum tube active components and point-to-point wiring with all leaded passive components (capacitors, resistors, inductors, lamps, etc.). I know this from first-hand experience working on a 1960's air traffic control radar system while serving in the U.S. Air Force. As with today, servicemen often get a bad rap undeservedly because of the low morals of some fellow practitioners. While it is unfortunately true that bad eggs...

Centralab Ceramic Capacitors

Centralab Ceramic Capacitors, February 1952 Radio & Television News - RF Cafe WebsiteMaybe it isn't so anymore, but according to Centralab the ceramic raw materials available in abundance in America were electrically superior to those being used in Europe since the early 1900s when German scientists first discovered the dielectric properties of the material. Ceramic capacitors represented a major advance in capacitor technology over liquid and paste dielectric types in most areas of electrical and mechanical specifications such as vibration, aging, vibration and shock, temperature, value stability, voltage and current handling, etc. Centralab ran this advertisement in Radio & Television News magazine spelling out all the...

Electrical Engineering Theme Crossword for July 10th

Electrical Engineering Theme Crossword Puzzle for July 10th, 2022 - RF Cafe WebsiteWith few exceptions, I, RF Cafe webmaster Kirt Blattenberger, have for more than two decades designed a custom crossword puzzle every week for the benefit of website visitors. This Electrical Engineering Theme Crossword Puzzle was created for July 10th, 2022. All crossword puzzles use a personally built dictionary of thousands of words and clues related to RF, microwave, and mm-wave engineering, optics, mathematics, chemistry, physics, and other technical subjects. As always, this crossword puzzle contains no names of politicians, mountain ranges, exotic foods or plants, movie stars, or anything of the sort unless it/he/she is related to...

CNES RF Propagation Calculations DLL

CNES RF Propagation Calculations DLL - RF Cafe Cool ProductMany thanks to RF Cafe visitor Michael M. for sending me a note about a very handy RF propagation software tool provided free of charge by the French organization Centre National d'Études Spatiales (CNES, National Centre for Space Studies). The PROPAGATION dynamic link library (DLL) contains functions to compute propagation losses according to ITU-R P.† recommendations. Versions are available for both 32- and 64-bit Windows and Linux operating systems, as well as for the C and Visual Basic programming languages. Very conveniently, the DLL functions can be referenced from within an Excel spreadsheet as well*, and a demo...

Novel Radio Items

Novel Radio Items, August September 1940 National Radio News - RF Cafe WebsiteMy father used to refer to the "sweet-voiced lady predicting the weather over and over again" as my girlfriend because I would call the "WEather 6-1212" phone number (936-1212) so often. It really wasn't because I was infatuated with her voice, it's that I was obsessed with weather forecasting. Most of my free time as a kid and teenager was spent building and flying model airplanes and rockets, and at eighteen years of age I began taking full-size aeroplane flying lessons, so my world revolved around a zone extending from terra firma up to about 5,000 feet AGL. This collection of communications news items in a 1940 edition of National Radio News...

One Problem in Choosing Test Leads

One Problem in Choosing Test Leads, July 1953 QST - RF Cafe WebsiteIn this 1953 QST magazine article, Authors Cohen and Hessinger warn about the need to consider the capacitive loading effects of shielded and closely-space test leads when measuring other than direct current or very low audio or line frequencies. Lead capacitance is especially likely to affect measured values when the frequency is high and/or the source and load impedances are high. As was common in the day, capacitance units of μμfd (micro-micro farads = 10-6 x 10-6 = 10-12 F) are cited, which is equivalent to units of pF (10-12 F)...

Electronics for Tomorrow

Electronics for Tomorrow, April 1955 Popular Electronics - RF Cafe WebsiteCooling devices based on the Peltier effect were first demonstrated by French physicist Jean Charles Athanase Peltier when he noted the presence of heating or cooling at an electrified junction of two different conductors types (opposite of a thermocouple). Widespread commercial use depended on finding efficient materials that could be produced inexpensively. Music synthesizers, to be practical, needed to await the availability of miniaturized electronics like transistors and memory elements. Light amplification similarly depended on affordable sources to be anything more than a laboratory curiosity. Fortunately, by the mid 1950s such entities were becoming...

Transistor Replacement Problems

For the Record: Transistor Replacement Problems, February 1966 Electronics World - RF Cafe WebsiteBy 1966 the dominance of vacuum tubes, particularly in new products, as stated by Electronics World magazine editor William Stocklin, "...is gradually passing behind us." The Transistor Replacement Problems highlighted in this article refer primarily to finding second (or third or more) sources for transistor types already designed into existing products as semiconductor manufacturers move on to new and better (often much better) devices. There was little motivation for companies to dedicate scare resources to making low volumes of legacy devices just to service radios, televisions, phonographs, etc., which, to be honest, they probably preferred...

VIP's Are Hams Too!

VIP's Are Hams Too!, March 1958 Popular Electronics - RF Cafe WebsiteWhat do General Curtis LeMay, Arthur Godfrey, Herbert Hoover, Arthur Collins all have in common? They were Ham radio operators. A lot of famous people were/are Hams, with these and a few other notables mentioned in this March 1958 edition of Popular Electronics magazine. Conspicuously missing is one of modern day's most renowned Hams, and that's Walter Cronkite, KB2GSD (died in 2009). His broadcast career stretched back to World War II, so he was definitely around long enough. Maybe the author just didn't know; after all, he couldn't just look it up on the Internet or in an FCC computer database. By now you probably know that actor...

Electronics Against Cancer

Electronics Against Cancer, August 1959 Popular Electronics - RF Cafe WebsiteThe medical x-ray machine shown here reminds me of the "Illudium Q-36 Explosive Space Modulator" contraption Marvin the Martian wanted to use in "Hare-Way to the Stars" to disintegrate the Earth (because it blocks his view of Venus). Of course our hero Bugs Bunny thwarts his plan, whereupon Marvin asks, "Where's the kaboom?" Can you imagine being fraught with cancer and getting strapped into a chair with that huge hypodermic-needle-looking thingy pointed at you, as shown in this 1959 issue of Popular Electronics magazine? The Caduceus sword in the pic doesn't help matters, either. The trauma of such an experience might have been worse...

Rectifying Without Rectifiers

Rectifying Without Rectifiers, July 1952 Radio-Electronics - RF Cafe WebsiteIt took a couple times reading through this "Rectifying Without Rectifiers" article to get the gist of what author H.B. Conant was talking about. He begins by pointing out the negative aspects of using nonlinear metallic rectifiers in a bridge circuit for an electric meter, then goes on to describe an improved "translator" circuit that uses - wait for it - nonlinear metallic rectifiers (or nonlinear resistors made of Thyrite material). If my interpretation is correct, basically the new and improved circuit incorporates a bias voltage that forces the nonlinear element (be it a metallic rectifier or a nonlinear resistance) to operate in a region which passes a higher current level to the meter...

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