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 Those of you who are not particularly interested
in
vintage electronic equipment will please indulge those of us who
are. I post these articles occasionally to remind people of from whence we have
come. Whether you are an amateur radio operator or just a cellphone user, appreciation
is due to the pioneers who took the metaphorical arrows for us so that we may enjoy
the micro-size, low cost, high quality communications available today. The full-height
equipment racks in the photos were standard fare in the 1930s for long distance
(DX) shortwave operators - often only for CW (Morse code). "User serviceable parts
inside' was the rule rather than the exception. As much as I like waxing...
 Anritsu announced the launch of its new
Tensor Vector Network Analyzer (VNA) at IMS 2026. The Tensor VNA represents
a major advancement in RF and microwave network analysis, delivering modern, scalable
architecture designed to support the most complete and demanding measurements like
amplifiers, filters, frequency convertors, and other advanced VNA measurements.
Tensor VNA sets a new benchmark in vector network analysis with its revolutionary
source-per-port architecture, integrated AI intelligence, and exceptional power
handling. Engineered to meet the evolving requirements for aerospace and defense,
semiconductor, active and passive device measurements, signal integrity, research
and development, and millimeter wave / waveguide...
 Here
is a reprint of an article I had published in Wireless Design & Development
magazine in 1995. Some of the references are a bit dated, but the info is all still
very useful. Waypoint Software is now RF Cafe, and TxRx Designer is now Shareware
by the name of RF Workbench. With the advent of high speed personal computers, a
very insightful graphical method of determining inband mixer spurious products has
been largely forgotten. The
Spur Web™
(my name trademark, but used widely w/o attribution) chart rapidly identifies both
inband and out-of-band spurs, affording a pictorial view of where conversion system
frequencies lie with respect to all spur products. A comparison...
 The neighborhood where I grew up in the
1960s and 1970s was about 25 to 30 miles from the "big three" network television
broadcast stations (ABC, CBS, NBC) in Baltimore and Washington, D.C. That is considered
a fairly long distance in the over-the-air TV realm. Knowing what I know now, I
am somewhat surprised that those in our area were able to receive programs as well
as we did when all the homes I recall had just a single, standard multi-element
antenna on the roof. If anyone had stacked, phased array setups like this
Finco Co-Lateral TV Antenna installed, I certainly do not remember
any. Most of the antennas in Holly Hill Harbor and the surrounding communities did
not even have an antenna rotator, yet evidently were pulling in signals satisfactorily
- and without needing to be mounted on a tall...
 In this Radio & Television News
magazine article, author Jack Gallagher derives a formula for the number of turns
of wire to wind on a form of given dimensions for a parallel
constant-resistance network. He argues that although commonly
used formulas like that of Wheeler provide the number of turns needed to achieve
a desired value of inductance, it does not predict the size of cross-sectional shape
of a coil form that results in an optimal configuration. His work applies to audio
frequency divider networks like those used for speakers to steer specific frequency
ranges to a woofer, midrange, and tweeter trio; hence the need for "constant resistance"
(e.g., for standard 8 Ω or 16 Ω speakers)...
 Satellite direct-to-device (D2D) networks
represent the next frontier in mobile connectivity, promising to eliminate dead
zones by linking ordinary cellphones directly to orbiting satellites. Companies
like SpaceX with its Starlink system, AST SpaceMobile, and others are racing to
deploy constellations that can serve standard smartphones without specialized hardware.
The technology relies on large phased-array antennas in space, advanced beamforming,
and new spectrum-sharing arrangements with terrestrial carriers. Proponents argue
D2D will bring emergency communications and basic connectivity to remote areas worldwide.
Critics raise serious concerns...
 During my electronics technician days at
the Westinghouse Electric Company's Oceanic Division in Annapolis,
Maryland, I spent the first couple years building printed circuit boards, wiring
harnesses, and system-level assemblies for U.S. Navy sonar systems. We had some
really slick stuff like towed vehicles with transducer arrays along the sides, nose
cones for smart torpedoes, flow sensors, proximity fuse elements, etc. Exposure
to all that, and the super-smart people that designed it, fuelled my desire to go
to the trouble of earning an engineering degree. One of my tasks for a while was
to build the transducer arrays, which entailed building the hundreds of tiny transducer
elements. One of the phased...
 With the extreme volatility of today's
stock market, I thought this might be a good time to re-post an article I wrote
back in 2012 entitled "Arbitrage
via Microwaves." The ±200 point daily swings of a mere 8 years ago seem
paltry compared to ±1,000 of late. The original page on the IEEE Spectrum
magazine website is dead now, so I had to change the hyperlink to an archived page
on The Wayback Machine - a
great resource for you to remember if you ever need to retrieve a webpage that has
been disappeared [sic]. My piece begins: "If you have wondered why the world's
stock markets behave the way they do, why the DJIA falls 150 points on one day on
news of Greece leaving the euro...
 You wouldn't know it from the lineup
of
Crosley Corporation radios and turntables appearing in department
stores, but the company also manufactures dishwashers, ranges and freezers, clothes
washers and dryers, and air conditioners. That is still a small chunk of what Crosley,
based in Cincinnati, Ohio, made back in the middle of the last century, including
cars and trucks, a small private airplane (the Moonbeam), television sets and even
had a television broadcast station, as well as other items that were part of the
mainstream of American life. Take a look at their About Crosley webpage for more
insight. Amazingly, along with the extensive line of retro radios and turntables,
they still also...
 What got my attention in this 1955 Radio &
Television News magazine article was the "picture-on-the-wall" concept being predicted by General Electric
(G-E) engineers, based on its light-amplifying phosphor invention. Determining exactly
how the device works is difficult based on the information given, but it appears
that the ultraviolet light source which is being amplified is projected onto the
surface of the amplifying substrate, and then an exact duplicate of the image is
reemitted toward the viewer. The conceptual drawing of a large screen hanging on
the wall is most likely driven by a UV projector located near the ceiling, akin
to how the large screen home theaters popular in the early...
 When most people are asked to name
prolific inventors, people like Thomas Edison and George Westinghouse,
with 1084 and 361 each, respectively, come to mind - at least for the United States.
As of this writing, Kangguo Cheng of IBM holds the record with 2039 U.S. patents
assigned. Nikola Tesla had about 300 patents. Lee de Forest, the subject of
this 1937 Radio-Craft article, had a little over 180 patents. That still
qualifies as prolific by my estimation. However, there is more to ranking a person's
inventive worth than the number of patents awarded - like how profoundly his or
her invention(s) impacted the world. For instance, Alexander Graham Bell had a mere
18 patents...
 Development of the
cavity magnetron during World War II helped change the destiny
of Allied forces through using high frequency radar with enough power to detect
distant targets while using frequencies which were out of the normal detection bands
of Axis forces' receivers. Most equipment at the time could not operate efficiently
(or at all) above a few hundred MHz. It was considered a top-level secret with great
concern that the technology not fall into the hands of German and Japanese scientists.
According to this early post-war advertisement in a 1945 issue of Radio News,
Bell Labs was totally consumed by the development of magnetrons, and was relieved
to finally be able to boast of its...
 Exodus Advanced Communications presents
the
AMP20162, a high-power, solid-state amplifier designed for low frequency applications,
including radiated susceptibility (RS103), EMI/RFI lab and general broadband testing.
Covering 10 kHz to 250 MHz, this wideband system ensures signal integrity
and flat response, making it a reliable choice for demanding environments. The AMP20162
provides between 2500 and 3000 W, typical, across the frequency range and boasts
a P1dB of 1700 W. Utilizing a Class A/AB design, the AMP20162 supports all
modulation types and 64 dB gain while maintaining harmonic performance around...
 While
FM broadcasting (frequency modulation) began in the United States
in the late 1930s, it was not until after World War II and even the Korean
War, in the 1950s, that the major shift to FM took place. It took even longer for
FM to get a foothold in Europe mainly due to the emphasis on rebuilding essential
infrastructure and manufacturing destroyed by the war. As this article points out,
the newer FM radio features allowed it to thwart some of the propaganda efforts
of the Soviets in East Germany who would be stuck in technologies that lag two or
more decades behind the free world even to this day (ain't Communism / Socialism
great?). The "medium-wave band" referenced...
 Welcome to the RF Cafe
Frequency Mixers
Quiz, a technical assessment focused on the critical non-linear components that
enable frequency translation in transceivers and test equipment. Whether you are
designing heterodyne receivers, analyzing local oscillator (LO) leakage, or striving
to minimize spurious intermodulation products in your signal chain, a deep understanding
of mixer dynamics is indispensable for high-performance RF design. This quiz covers
the core principles of frequency conversion, exploring topics such as conversion
loss, isolation, port-to-port feedthrough, and the generation of mixing products.
By testing your grasp of these essential concepts, you refine your ability to optimize
your system's dynamic range...
 Way back in the 1980s while working at Westinghouse
Oceanic Davison in Annapolis, Maryland, an engineer who knew I had recently obtained
a 1941 Crosley Model 03CB console style radio generously gave me his
B&K Dyna-Quik Model 650 Vacuum Tube Tester. It is a very comprehensive
portable tester used by many professional radio and television servicemen. My tester
also had the Model 510 Accessory Socket Panel that added an ability to test 50%
more tube types. One indication that it is one of the later model tube testers is
the inclusion of a transistor testing socket. Unlike testing vacuum tubes, all of
which plugged into sockets to make them easily replaceable, testing a transistor...
 Punch cards have been used in computer systems
since the very early days of digital programming. They were probably the first form
of read-only memory (ROM), come to think of it. I hate to have to admit it, but
the meager computer used in my high school computer lab (circa early-mid 1970s)
used
punched cards. I never took the class, but stories abounded of
how pranksters would shuffle a stack of punch cards while the student programmer
wasn't watching and then get a good laugh when nothing worked. There are also
plenty of cases where a stack was inadvertently knocked onto the floor and had to
be laboriously re-ordered. IBM is the brand that comes to most people's minds
when thinking...
 As with my hundreds of previous
science and engineering-themed crossword puzzles, this one contains
only clues and terms associated with engineering, science, physical, astronomy,
mathematics, chemistry, etc., which I have built up over nearly two decades. Many
new words and company names have been added that had not even been created when
I started in the year 2002. 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, Russia, for...
 Despite all the prefabricated, relatively
inexpensive products available these days, there are still many people who like
to build their own projects. Whether electrical or mechanical - or both - some sort
of
enclosure is usually involved. Often, you can cannibalize an existing,
retired project to use its chassis or find a product at Walmart or a home improvement
store that does not cost too much that you can buy just to get its enclosure. Buying
a pre-formed chassis for your project can get expensive, so there are times when
the best option is to obtain a piece of sheet metal (which can also be expensive)
and bend it yourself. If you have never attempted such an endeavor, believe me it
can be...
 Einstein's theories of relativity revolutionized
our understanding of space, time, and gravity. Special Relativity (1905) rests on
two postulates: the laws of physics are the same in all inertial frames, and the
speed of light in vacuum is constant for all observers. From these flow time dilation,
length contraction, relativistic mass, and the famous equation E=mc². General Relativity
(1915) extends these ideas to include acceleration and gravity by treating gravity
not as a force but as the curvature of spacetime caused by mass and energy. The
equivalence principle - that gravitational acceleration is locally indistinguishable
from inertial acceleration - is its cornerstone. Importantly, General Relativity
fully subsumes Special Relativity: in regions where gravity is negligible (flat
spacetime)...
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Loading history...
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.
 According to this full-page advertisement
in the June 1955 issue of Radio & Television News magazine, Bell Telephone
Laboratories was responsible for designing and fielding "waveguide pipe," aka flexible circular waveguides. According to
other historical sources, both George Southworth of Bell Telephone Laboratories
and Wilmer Barrow of the Massachusetts Institute of Technology (M.I.T.) independently
and simultaneously developed circular waveguide, but the early devices were rigid
pipe rather than being fabricated from tightly wrapped, insulated wire that permitted
it to be bent rather than requiring separate corner and offset pieces. Insertion
loss and VSWR is typically not...
 Not very long ago I mentioned
Jean Shepherd (original assignee of W9QWN and later K2ORS call
signs) as being one of my favorite old-time radio broadcasters (1960s-1970s). Jean
was famous for recounting stories of his own life and for reporting news of the
time in a way that could hold you in rapt attention from beginning to end. His humor,
wit, and command of the English language was acknowledged by his contemporaries.
If you listen to enough of his broadcasts you will notice the frequent mention of
electronics and his experiences as a licensed amateur radio operator beginning at
a tender young age. Just recently I listened to him recount his first day in high
school...
 Having recently struggled a little with re-stringing
the dial cord on a vintage Realistic (Radio Shack) Patrolman-50 Radio, it really
became apparent why the
Sams Photofact Folders were of such value to electronics servicemen.
Unlike the tangled mess of dial cord shown in the ad, I had the advantage of being
able to carefully open the chassis and photograph the routing and wrapping of the
broken dial cord around pulleys and shafts. Even so, a lack of experience required
some trial and error to get the tensioning correct. No doubt many unqualified radio
owners attempted to fix their own broken dial cords prior to breaking down and committing
to spending a few bucks to have a pro do it...
 If you were hanging around here in 2014,
you might recall a paper I published titled, "Drone-Based Field Measurement System™ (dB-FMS)™." Since that time,
I have seen news items about a few companies using drones to measure antenna radiation
patterns and many more others are coming online all the time. Some amazing working
systems have been implemented that seem to perform very well. I'm not saying
they got the idea from my article because more than one person can have the same
brilliant idea ;-). It's just good to know that my concept had some merit in
the real world...
 My mother loved
Norman Rockwell paintings for their ability to get to the heart
of Americana. She was an avid collector of books on Rockwell and decorated plates
for display - as avid as one can be on my newspaper classified ad manager father's
feeble salary, anyway. I, too, have a great appreciation for Rockwell's great
talent to choose his subject matter and models and to, when fitting, include a nearly
photographic level of detail within. The Saturday Evening Post magazine featured
many of his works spanning from 1916 until 1971 - from the middle of World War I
and on through World War II, Korea, and Vietnam. Summer, spring, fall, and
winter; Christmas, Easter, Veteran's Day...
 "Stratovision" sounds about as serious as "Wonkavision,"
but unlike the candy maker's fictional machine that transported chocolate bars
across the room, Stratovision was in fact a serious proposal. It was an early form
of satellite television. Since orbiting communications satellites would not be practical
for another decade, Westinghouse devised a system in 1945 using aircraft flying
at high altitude to relay television signals. Engineers calculated that 14 airplanes
circling at 25,000 feet could provide coverage to 78% of the country. By 1950 they
had a working system, but needless to say (because nobody has ever heard of it...
except you, now), the concept ultimately did not pan...
 "If the car is parked in a dark remote spot
it is better to do the job where the car is. This is because auto burglary is a
lesser crime than stealing the whole damn car." That remark was made by a 'former'
thief who ostensibly gave up a life of crime after spending nearly two decades in
the slammer for various infractions of the law. One of his specialties was breaking
into cars to
steal radios - AM, FM, CB, Ham, or whatever was available. Mr. X
volunteered his insight for the benefit of QST readers who might want to take proactive
steps to help minimize the chance of being a victim. The year was 1967, but you
can bet the same mindset pervades the thinking of modern day break and grab...
 While not a second-hand store junkie, I do
like to occasionally make the rounds of the local Salvation Army, Goodwill, and
other independent shops to see what kind of relics are donated. Since eBay, Etsy,
and their kind have gained immensely in popularity, it is getting harder to find
anything useful other than clothes and kitchen wares. A few months ago Goodwill
had a 1910s vintage
cabinet -style Edison disc phonograph (as opposed to wax cylinder)
that was in very good condition, complete with a handful of styli and a couple old
records. The original finish over smooth mahogany and burl veneers had only a few
scratches and could easily be polished to look practically new...
 This installment of the After Class series
in the December 1957 edition of Popular Electronics deals with inductors.
It is a beginner-level introduction to how
reactive components behave in circuits. For some reason the concept
of magnetism's influence on electrical current (present with inductors but not
capacitors) seems to be more difficult to comprehend than that of electrons, even
though James Clerk Maxwell shows in the mid 1800s that the two phenomena are interrelated.
I am tempted to say that back in the 1950s when this article appeared, people were
less familiar with the relatively new concept of electronics, but in thinking about
it, your typical 2019 reader is probably even...
 John T. Frye's monthly "Mac's Radio Service Shop" techno-drama, written in story form
- was usually an incognito lesson on circuit functionality or troubleshooting, how
to deal with customers, industry regulations and news, or an introduction to new
components and equipment. As the "Unusual New Equipment" title suggests, this time
Mac described a few new items added to the service shop to aid in their work. Often
when reading one of the episodes, I do a Google search on specific components or
equipment mentioned in the article. He describes a special-purpose CRT (Sylvania's
new 5AXP4 Television Receiver Check Tube) that could be used universally for troubleshooting
in place...
 Today, if Rohde & Schwarz, Keysight,
or some other major test equipment manufacturer announced during a trade show presentation
a new oscilloscope model with a "Breakthrough!" featured dubbed "Cali-Brain®," they would be laughed off the stage. The technology
truly was a breakthrough in terms of displaying peak-to-peak waveform measurements
in a numerical presentation along with a cursor line indicating the pk-pk extent
from the display. It was not as convenient as next-generation scopes that provided
a movable horizontal pair of lines with a direct digital voltage difference readout,
but it did take some of the guesswork and potential error out of readings on complicated
waveforms...
 The
battle between the serviceman and the customer is epic. The serviceman
knows the customer is out to cheat him of his rightful due for expertise and availability,
and the customer knows the serviceman will try to inflate the bill to finance his
exorbitant lifestyle. This story from a 1945 edition of Radio-Craft is
a humorous take on the subject at first glance from the customer's perspective,
but after reading it you might ascertain that it is really from the serviceman's
perspective. An article from a 1957 edition of Radio News magazine
titled "Strategy for C.O.D. Service" was written as serious advice to servicemen
to avoid being ripped off by customers typified by the one ostensibly penning this
article...
 Each week, for the sake of all avid cruciverbalists
amongst us, I create a new
technology-themed crossword puzzle using only words from my custom-created
lexicon 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, such as Hedy Lamarr or the Bikini Atoll, respectively...
 Anytime I see a photo or story about the
1964 New York World's Fair, I immediately think of the scene
at the end of the first "Men in Black" movie when Agents K and J face off with the
alien invader who has come to Earth in search of "The Galaxy." This story from an
April 1964 issue of Electronics magazine reports on preparations made for
the grand opening on April 22 of that year. Based on the typical three to six month
lead time for publishing magazines back in the day, this material would have been
gathered long ahead of time. Of course now that half a century has passed we hardly
consider any of the whiz-band technology presented there as being anything wonderful..."
 I did a little research on this article about
John H. Nelson's work on how the positions of planets affect
magnetic storms on Earth. It looked a little more like astrology
than science, but as it turns out, Nelson's findings gained support in both
the astronomical and meteorological fields. Naturally, the astrology crowd claimed
him as part of their goofiness, but that wasn't Nelson's fault. He published
a book in 1974 titled ,"Cosmic Connections." Yeah, even that sound like an astrology
title - poor choice (or maybe he was trying to fool the contemporary Pharisees in
to buying his book). The book is out of print now, and I could not find any contemporary
work that leverages Nelson's work...
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