See Page 1 |
2 | of the November 2025 homepage archives. Friday the 28th
 With the high degree of computer automation
at this point in time, it is doubtful that many people still bother to perform digital
logic simplification manually by using a
Karnaugh Map. Online apps like this one (KarnaughMapSolver.com) do all the heavy
lifting for you, producing minterms, maxterms, a truth table, and a written-out
Boolean expression. Back in the late 1980s when I was working on my BSEE at UVM,
the Karnaugh Map, created by Maurice Karnaugh, of Bell Labs, was introduced in a
digital electronics course. It was a fairly easy concept to grasp. Is it taught
in electronics curricula these days? This 1975 Popular Electronics magazine
article provides a great introduction to the Karnaugh Map...
 Radio was a powerful
propaganda tool and strategic communications means toward the end of World War I,
and certainly in the lead-up to and during the course of World War II. Many
governments, including the United States and most European countries, forbade the
broadcasting of signals by anything other than an entity licensed for commercial
and/or military purposes. Amateur radio broadcasts were prohibited, although at
least here in the U.S. possession of a receiver for listening was still allowed.
Some of the regions controlled by Nazis did not even permit receivers - mainly because
the government did not want citizens listening to anything that could be considered...
 "In its latest set of trials Britains advanced
DragonFire laser weapon has been used to successfully target and shoot down
high-speed drones. According to an MOD statement, the trials - which were conducted
at the MOD's Hebrides range off the northwest coast of Scotland - involved above-the-horizon
tracking, targeting and shooting down of high-speed drones able to fly up to 650km/h,
a UK first for the technology. The trials were followed by the news that DragonFire
project lead MBDA - which heads up a consortium also including Leonardo and QinetiQ
- has been awarded a £316M contract to equip..."
 Sam Benzacar, of Anatech Electronics, an
RF and microwave filter company, has published his November 2025 Newsletter that,
along with timely news items, features his short op-ed entitled "AM
Radio Isn't Dead Yet." In it, he asserts that contrary to widespread narratives
of AM radio's imminent demise, data reveals the medium is not collapsing but adapting.
The 8-13% decline in stations since 1990 reflects market adjustments, not systemic
failure. AM maintains strong listenership in rural and mountainous regions where
geography limits FM reception, with radio overall outperforming television among
adults 18-49. Station closures follow local market dynamics...
 Mostly just old farts like me remember anything
about
LORAN (LOng RAnge Navigation). My familiarity with it came not
from boat navigation, but from airplane navigation. Before LORAN became totally
obsolete due to GPS (phased out in U.S. and Canada in 2010), the transmitter stations
were commonly tuned in in order to obtain positional fixes via triangulation. Whilst
taking flying lessons at Lee Airport, in Edgewater, Maryland, the ground instructor
included it in the lessons, and even the FAA Private Pilot exams had a question
or two on LORAN. The el cheapo Piper Colts that I flew were lucky to have a VOR
(VHF omnidirectional range ) receiver in it, so I never actually used LORAN. They
did have direction finders (DF), which could tune in, among other things, VHF television
station channels...
 When the concept
of
radio-refrigerators was presented in a 1933 edition of Radio-News,
it was not quite what has become reality today. At the time, the Radio Electrical
Exposition had recently been held in Madison Square Garden and the world was just
getting used to the miracle of radio waves - and refrigerators for that matter.
Radio-refrigerators never did make their way into the consumer market. Fast-forward
90 years and now we're seeing the advent of radio-refrigerators re-emerge, only
in a completely different format. This time, rather than playing shows from local
commercial broadcast stations, these appliances are communicating with Wi-Fi routers
to allow owners to check on status and contents from remote locations. A
Tesla spark gap transmitter...
Thursday the 27th
 This is my 68th Thanksgiving Day. It seems
like just a short while ago my sisters and I would be made to dress up in our Sunday
best to spend the day at our grandparents' house (mother's side). Most of my mother's
side of the family (many from the Eastern Shore), attended. We lived in
Holly Hill Harbor, and they
were on Carr's Wharf
Road, about five miles away (I couldn't afford to buy a house in either location
now). My father's family was in the Buffalo, NY, area. The food was great, but I
was always anxious to get home to my model
airplanes and rockets. Fast forward
to 1983 when Melanie and I celebrated our first Thanksgiving together, living in
Arnold, MD. Now, on our 43rd Thanksgiving, we live on my daughter's and son-in-law's
16-acre farm in Greensboro, NC. Our grandson,
Calvin, will enjoy his 3rd Thanksgiving meal today at our house. It has been
a wild ride, with many household moves and jobs in between. Melanie and I wish everyone
in the RF Cafe clan a very
Happy Thanksgiving!
 Anyone who watched the
WKRP in Cincinnati
TV sitcom back in the 1970s has to remember what was one of the funniest episodes
ever. Here is the 4 minutes that made Prime Time history. In this Thanksgiving episode,
station owner Arthur Carlson decided he would surprise the community with a good
deed - that doubled as a promotional stunt for his radio station - by dropping turkeys
from a helicopter for lucky shoppers at the local shopping mall. Watch the disaster
unfold as Les Nessman reports live, and then see Carlson's final comment that is
still used or alluded to in many comic routines. Posting this video is an RF Cafe
tradition. Have a Happy Thanksgiving!
 Not everybody with a high temperature
semiconductor application in need of heat dissipation has access to a thermal management
program with a database of available commercial
heat sinks and/or an ability to analyze a custom-made heat sink.
This article contains simple equations, a handy chart, and instructions on how to
use them to figure out what kind of heat sink you need for your project...
Wednesday the 26th
 As is usually the case, John Frye uses his
monthly "Mac's Service Shop" story to entertain whilst proffering a valuable lesson
in the field of electronics. Mac is famous for his superb knowledge of electrical
principles, and for his ability to troubleshoot and solve just about any problem
put before him. His sidekick technician, Barney, is a young Ham operator who often
needs the admonishment and/or wisdom provided by Mac. In this 1975 Popular Electronics
magazine piece entitled "Taming
Static Electricity," Barney is saved by Mac from the wrath of office girl Matilda
after she received an electrostatic discharge (ESD) shock intentionally administered
by the young man. Prior to the advent of microelectronic circuits, everyday ESD
was generally...
 While working at RF Micro Devices
(now known as Qorvo) on a project to improve the ESD ruggedness of
our RFICs, I had to do a number of presentations on progress over a span of about
two years. I desperately searched online for this episode of Welcome Back Kotter
titled "Sweathog Clinic for the Cure of Smoking." It was not available
at the time, but did show up for a short time sometime around 2008. Then, it disappeared
and was not available again anywhere until a few months ago when a DVD set for the
Welcome Back, Kotter television series went on sale at Amazon.com.
I quickly snatched a copy and produced this clip...
 "In a statement to the House of Commons,
Minister Al Carns declared that the United Kingdom is committed to defending 'every
inch' of its territory, including its critical
undersea networks and coastal security. The comments came after the Russian
spy ship Yantar entered UK waters earlier this week and was accused of shining lasers
at military pilots. The vessel is being closely monitored by the Royal Navy, having
previously been accused of attempting to map the UK’s submarine cable infrastructure,
The incident follows growing concerns about foreign interference and potential sabotage
to the UK's undersea infrastructure, which forms the backbone for the nation’s energy
supplies and communications..."
 IC designers have been striving to make
the "ideal" opamp ever since the device type was first conceived. An ideal opamp
has a certain set of well-defined properties that permit it be used in circuits
defined by neat mathematical equations without the need for compensating or limiting
terms. An example of compensation might be having an input impedance of something
other than infinite ohms that causes a voltage division effect on the input voltage,
and a limitation would be a gain-bandwidth product that prevents it from being used
in high frequency applications. Opamps appeared in electronics before semiconductors
came onto the scene, and a couple companies attempted to market prepackaged vacuum
tube opamps that plugged into a standard octal...
 I know I keep saying this, but it keeps
being true so I say it again: The
basics of electricity and electronics have not changed in the
last 75 or more years, so these articles from vintage issues of electronics magazines
are as applicable today as they were back then. If you are just getting into the
field of electronics, valuable information can be found here to supplement your
learning process. In fact, I have seen examples in some of these articles where
I re-learned something long-ago forgotten, and some of the stuff is rarely, if ever,
seen in contemporary writings. Regardless, making yourself aware of the work done
by pioneers in the industry is always valuable because it gives you a sense of approaches
taken that have led to success, and sometimes...
Tuesday the 25th
 John Mackenzie's 1966 Electronics
magazine article predicted a future where glass would transcend its role as a passive
material to become a primary semiconductor for devices like memories, transducers,
and switches. This forecast has proven remarkably prescient. While crystalline silicon
has dominated mainstream computing, the unique properties of amorphous materials,
now classified under amorphous semiconductors or phase-change materials, have become
foundational to modern technology. The most significant realization of this prediction
is in non-volatile memory, where chalcogenide glasses are the active material in
commercial Phase-Change Memory (PCM) and the memory cells of optical discs (CD-RW,
DVD-RW...
 Reactance charts were a dime a dozen (free,
actually) and appeared as regular features in electronics magazines in the days
before smartphone apps provided ready access to reactance versus frequency calculations.
This one was in the May 1959 issue of Electronics World. Calculators are
nice and indispensible in design work, but sometimes having "the big picture" of
how various values of inductance and capacitance "react" with changes in applied
frequency is often useful - especially if you are a newcomer to electronics. To
paraphrase a popular saying, "A reactance chart is worth a thousand calculators."
 "Researchers at the University of New Hampshire
have harnessed artificial intelligence to accelerate the discovery of
new functional magnetic materials, creating a searchable database of 67,573
magnetic materials, including 25 previously unrecognized compounds that remain magnetic
even at high temperatures. 'By accelerating the discovery of sustainable magnetic
materials, we can reduce dependence on rare earth elements, lower the cost of electric
vehicles and renewable-energy systems, and strengthen the U.S. manufacturing base,'
said Suman Itani, lead author and a doctoral student in physics..."
 My favorite character in the
1970s Prime Time TV show
Barney Miller
was Detective Sargent Arthur Dietrich. He was the serious intellectual with a very
dry sense of humor that came out at just the right moment. One episode has always
stuck out in my memory where a college student claims to have built a working model
of a thermonuclear
bomb as part of his Master's thesis project. All it lacks for detonation, per
him, is plutonium. The on-hand bomb squad expert ridiculed the idea of it being
any kind of real bomb, his decades of experience on the force being his guide
(still has all his fingers as proof of it). All the guys in the office
have just finished...
 Unlike even the vacuum tube type AM radio
in the dashboard of my parents' car in the early 1960s that were self-contained
units, even earlier radios designed for cars and trucks had their bulky electronics
mounted under the sea or in the trunk, with a remote volume and tuning control mounted
in the dashboard. That greatly complicated the installation as well as the design
of the radio. This circa 1940
Belmont Model 678 Auto-Radio is a prime example. Note the unique
cylindrical shape of the radio chassis, and that the remote control is a pushbutton
assembly with rotating knobs for tuning and volume. Operating from a 6 volt DC car
battery (12 volts came later), these radios required a "vibrator" circuit to convert
DC to AC (and back to a higher level DC) in order to transform to a couple hundred
volts for the plate voltage of the tubes...
Monday the 24th
 When I saw this advertisement for
Monsanto Electronic Instruments in a 1966 issue of Electronics magazine,
I wondered whether it was the same company that makes the controversial Roundup™
weed killer. The Wikipedia entry discusses only the chemical company. Before doing
a Web search on it, I asked AI: "Does Monsanto Electronic Instruments from the 1960s
and 1970s share any company lineage with the Monsanto Chemical Company that makes
Roundup?" It responded: "No, the two companies share a name but no corporate lineage.
Monsanto Electronic Instruments was a subsidiary of the Monsanto Chemical Company
from 1969 until 1979, when it was sold to American Solid State..." To that, I replied:
"Wait, that sounds like it does share lineage." To which it responded: "You're right
to catch that...
 Designing a
log periodic antenna is a piece of cake. Just punch in your computer
program or smartphone app a few parameters for frequency range, power handling,
directivity, impedance, etc., and out pops boom and element lengths, diameters,
and spacings - and probably radiation gain profiles for elevation and azimuth. That
is the way it's done today. However, when Dwight Isbell and Raymond DuHamel of the
University of Illinois came up with the log periodic concept in 1958, they did not
have the convenience of a computer or even a hand-held calculator. Slide rules and
logarithm tables were the order of the day. After trudging through the equations
for building the antenna...
 Who paid for the infrastructure to charge
this beast? Normal users' electric bills have skyrocketed to provide the capability.
It is ironic that there is not a shade of green in this picture. We're also paying
to fund AI and cryptocurrency datacenter energy needs. We've been scammed. Oh well,
at least Big Bro saved us from Covid [sarc]. "The
world's largest
battery-electric ship is now testing the limits of what megawatt-scale charging
and battery storage can do. Unveiled in May by Australian shipbuilder Incat Tasmania,
Hull 096 started receiving electrical charge for the first time last month. The
ship's battery system is 85% installed, with two of its four battery rooms charged
as of publication. The ship's 40 MWhr energy storage system..."
 It was only the first day at engineering
college and already their first familiar techno-caper was underway. Indiana's Parvoo
University was about to get an initiation into the world of
Carl Anderson and Jerry Bishop, who during their high school years
together solved many a mystery and pulled many a prank in their hometown somewhere
in northern Indiana. As with all of John Frye's tales this one mixes serious electronics
topics with a bit of fun and a life lesson. There were no "bad guys" here as in
many other episodes, but the boys did get an unexpected introduction to Parvoo U.'s
president! Despite the story's title, the day ended well...
 In rare final few spare minutes of the workweek,
try your hand at this "Electronics Helix Puzzle," provided by Mr. James Kimsey in
a 1971 issue of Radio-Electronics magazine. It it not as much of a challenge
as a classical crossword puzzle, but is still worth attempting. In some ways, though,
if you get stuck on a word there is more help available with a standard crossword
because there are more than just two (the first and last letter in this case) intersecting
letters available to help. If after completing this Electronics Helix Puzzle you
would like to try your hand at one of those traditional type crossword puzzles,
consider working one (or more) of my weekly...
 Anritsu has been a global provider of innovative
communications test and measurement solutions for more than 120 years. Anritsu manufactures
a full line of innovative components and accessories for
RF and Microwave Test and Measurement
Equipment including attenuators & terminations; coaxial cables, connectors &
adapters; o-scopes; power meters & sensors; signal generators; antenna, signal,
spectrum, & vector network analyzers (VNAs); calibration kits; Bluetooth &
WLAN testers; PIM testers; amplifiers; power dividers; antennas. "We've Got You
Covered."
Friday the 21st
 It is always interesting to read
industry news stories from decades ago to see when products and techniques that
we take for granted these days were just being introduced. Per this 1966 issue of
Electronics magazine, the U.S. Air Force studied a global network of seismic
arrays, modeled on Montana's Large Aperture Seismic Array (LASA), to detect nuclear
tests. The project aimed for a 10x sensitivity increase, potentially classifying
over 80% of global earth shocks. "High Costs Keep Auto Electronics at a Minimum,"
claimed one headline, its author likely never imagining the overwhelming amount
of electronics in modern vehicles - which still adds significant cost. The Gemini-XI
mission demonstrated a critical first-orbit...
 Pulse modulation comes in many forms, including
pulse position modulation (PPM), pulse width modulation (PWM), pulse frequency modulation
(PFM), pulse amplitude modulation (PAM), and pulse code modulation (PCM). In addition
to providing a nice introduction to the concept of pulse modulation, author Herbert
Kondo covers the basics of each type and then discusses their application in various
communications systems. The first time I recall encountering pulse modulation was
in the mid-1970s with radio control systems for model airplanes. Pulse position
modulation was the scheme used in both AM and FM sets. Modern R/C systems use frequency
hopping spread spectrum (FHSS), direct sequence spread spectrum (DSSS), or a combination
thereof...
 "An upbeat Elon Musk, with his newly approved
trillion-dollar pay package, talked to a very select group of investors at the Tesla
annual shareholders meeting yesterday in Austin, Texas, and told the audience he
had chips on his brain and planned to build a 'Tera
fab' that could potentially produce a million wafer starts per month to meet
chip demand for Tesla alone. Musk said that all he could think about was chips at
the moment. He also said that with his AI5 chip and the planned AI6 chip, he did
not think existing suppliers could meet demand. As a result, he would consider some
collaboration with Intel..."
 Having worked around resistors and capacitors
for more than four decades comes in handy when presented with 'simple' quizzes like
this one that appeared in a 1963 Popular Electronics dealing with
RC circuits. Still, there is always some trepidation involved
when being subject, even voluntarily, to a test of any sort, regardless of whether
you are fairly confident that it will be a lead pipe cinch, a cake walk, child's
play, so to speak. Even if nobody else will bear witness to your effort, you would
feel like a real moron if you missed even one of those simple questions that anyone
with your level of experience should get right without even having to think about
it. Such is the irrational fear I have when taking these quizzes...
• FCC Intent to
Delete Minor Part 97 Provisions
• Intel
Retreat Shifts EU Semiconductor Reality
• GSA Reports
Evolving Global Spectrum Strategies
• UK Telcos Secure
mmWave Spectrum
to Boost 5G
• 41% of
Schools Report AI Cyber Incidents
 While this article is directed at amateur
radio operators who want to explore working in the microwave bands, it is good fodder
for anyone who wants a fundamental introduction to
waveguides, resonant cavities, distributed elements, and atmospheric
propagation. If that describes you, and particularly if you have formulaphobia,
then start reading. Even though the article appeared in a 1952 issue of Radio &
Television News, the list of frequency band allocations are not much different
than today so the information is useful. Unknown to many is that in the early part
of the last century Amateurs pioneered the use of microwave bands when the Federal
Communications Commission (FCC) allocated the spectrum to them since many "experts"
considered it unusable...
 Empower RF Systems is the technological
leader in RF & microwave power amplifier solutions for EW, Radar, Satcom, Threat
Simulation, Communications, and Product Testing. Our air and liquid cooled amplifiers
incorporate the latest semiconductor and power combining technologies and with a
patented architecture we build the most sophisticated and flexible COTS system amplifiers
in the world. Solutions range from tens of watts to hundreds of kilowatts and includes
basic PA modules to scalable rack systems.
Thursday the 20th
 Integrated circuits were just entering the
mainstream of electronics in 1966 when this two-page
Motorola spread appeared to promote some new monolithic IC amplifier products.
Monolithic means everything is contained on a single substrate, as opposed to a
hybrid circuit with an IC die and one or more discrete components contained inside
a can. You'd have to be an old guy (like me) to realize that High-Speed Core Memory
Sense Amplifier refers to one of four wires (x-axis, y-axis, sense, inhibit) that
were threaded through magnetic core memories in use before monolithic memory was
available. As reported in this same issue...
 This story from a 1964 issue of Electronics
magazine is close to home - literally. Well, it was close to home at the time, anyway.
It reports on the work done by the
Electromagnetic Compatibility Analysis Center "...jutting out
on a pier across the broad Severn River from the United States Naval Academy at
Annapolis." I grew up in the 1960s and 70s just a few miles from there and distinctly
recall seeing all the antennas in the area, including the now decommissioned and
removed acres-big ELF submarine communications antenna farm. The Annapolis location,
with its proximity to Washington, D.C., was the home to many government and military
installations and defense contractors. It was an electromagnetic signal-rich environment...
 "Electromagnetic waves with frequencies
between microwave and infrared light, also known as
terahertz radiation, are leveraged by many existing technologies, including
various imaging tools and wireless communication systems. Despite their widespread
use, generating strong and continuous terahertz signals using existing electronics
is known to be challenging. To reliably generate terahertz signals, engineers often
rely on frequency multipliers, electronic circuits that can distort an input signal,
to generate an output signal with a desired frequency. Some of these circuits are
based on Schottky..."
 Even after computers became commonplace
in cubicles and laboratories, engineers and technicians kept design nomographs around
for cobbling together attenuators, filters, voltage dividers, etc. Trade and hobbyist
magazines like Electronics World used to print them as full-page features
on a regular basis, and I have posted many of them on RF Cafe over the years. This
particular "Symmetrical T & H Attenuator Nomograph" appeared in a 1959
issue. Maybe the editor thought that "Symmetrical T, H, O, and Pi Attenuator Nomograph"
would be too long of a title and that's why the "O" and "Pi" was omitted even though
they are clearly included in the chart. As can be seen by inspection of the
circuit constructions, the T and Pi configurations are "unbalanced" 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 village in the Andes mountains.
You might, however...
 LadyBug Technologies was founded in 2004
by two microwave engineers with a passion for quality microwave test instrumentation.
Our employees offer many years experience in the design and manufacture of the worlds
best vector network analyzers, spectrum analyzers, power meters and associated components.
The management team has additional experience in optical power testing, military
radar and a variety of programming environments including LabVIEW, VEE and other
languages often used in programmatic systems. Extensive experience in a broad spectrum
of demanding measurement applications. You can be assured that our Power Sensors
are designed, built, tested and calibrated without compromise.
Wednesday the 19th
 The more things change, the more things
remain the same. To wit: "When this circuit learns your job, what are you going
to do?" asks a poster now appearing widely in subways and buses. That statement
appeared in a 1966 issue of Electronics magazine that was reporting on
the state of the art in
computer-aided design (CAD) of circuits. People are saying the same thing
today about Artificial Intelligence (AI). The fact is that AI has been around for
as long as there have been machines capable of solving problems, detecting errors,
and making suggestions for improvement. If you think maybe high capability CAD is
relatively new on the scene, or that early attempts were extremely primitive, disabuse
yourself of that notion by reading through the article. Inputs were via punch cards
and tape, but the mathematical modeling and matrix functions would make most modern
day engineers' eyes roll back in his head. Transistor (BJT and FET) models were
c
 "Ground is ground the world around," is an oft repeated saying
when talking about making electrical connections to Earth ground. In a general sense
that is true, especially when referring to electromagnetic radio signals and antenna
systems that are in some manner dependent on the common connection. However, when
you are working within the confines of a localized electronic circuit such as on
a printed circuit board or inside a chassis, there is no guarantee that without
proper precautions ground is not at the same potential everywhere. Poor (high impedance)
soldered, crimped, and bolted connections are among the prime offenders that cause
voltage differentials to arise between points intended to be equipotential. RF frequency
signals are particularly sensitive to even a minor divergence...
 "Artificial
intelligence (AI) is touching nearly every corner of the business world right now,
and supply chains are no exception. What began as small experiments in forecasting
and robotics has evolved into practical tools for improving visibility and response.
Companies are using AI to identify risks earlier, reroute shipments when needed
and manage data across increasingly complex networks. Supply chain organizations
are now using AI in practical ways to solve routine problems. In 'How
AI Is Reshaping Supply Chains,' Olivia Farrar discusses how the technology can
'scan thousands of failure events' to pinpoint early warning signs of ..."
 You don't see jobs advertisements like this
anymore. Here is an ad that appeared in the the July 1944 edition of QST
(the American Radio Relay League's, ARRL's, monthly magazine), placed by
Raytheon Manufacturing Company (now just Raytheon Company), looking
for tube design, test, and processing engineers. Licensed amateur radio operators
were in high demand during the war years because of their knowledge and enthusiasm
for electronics and wireless communications. I hope you didn't come to this page
hoping to really find a tube designer job available. Of course, there are still
vacuum tubes being designed for TWTs and magnetrons, but those are few and far between...
 From the mid 1950s and through mid 1970s,
Popular Electronics magazine ran a series of articles entitled "Solid State"
in order to facilitate the electronics industry's effort to move people from vacuum
tubes to semiconductors. In fact, if Solid State ran every months since its beginning,
this being installment 182 means it began in 1956 - just eight years after the transistor
was invented. Even though the commercial industry had already shifted to almost
exclusively transistorized products, a large part of the consumer base had been
raised on tube radios and televisions. In this case, the news is in regard to Bell
Telephone Labs' recent invention of the
semiconductor charge coupled device (CCD) - the heart of all modern
imaging systems. Prior to the CCD, a vidicon tube, which as the name...
 Reactel has become one of the industry leaders
in the design and manufacture of RF and microwave filters, diplexers, and sub-assemblies. They
offer the generally known tubular, LC, cavity, and waveguide designs, as well as
state of the art high performance suspended substrate models. Through a continuous
process of research and development, they have established a full line of filters
of filters of all types - lowpass, highpass, bandpass, bandstop, diplexer, and more.
Established in 1979. Please contact Reactel today to see how they might help your
project.
Tuesday the 18th
 This 1964 Popular Electronics magazine
article captures radio astronomy's pioneering spirit when
Jupiter's radio emissions were still a novel discovery. Dr. Smith's work demonstrated
remarkable accessibility - using modified commercial receivers rather than specialized
microwave arrays typically associated with radio astronomy. The piece highlights
key challenges of early planetary radio research: navigating ionospheric interference,
coordinating multi-site observations for better resolution, and operating in crowded
shortwave bands. Researchers were still theorizing causes and practical applications.
The invitation for amateurs to participate (see my custom sky map overlay)...
 When you read about price wars in the
integrated circuit (IC) realm, you naturally think of manufacturers
in Asian countries, since even the products of American companies are made overseas
nowadays (unfortunately). Such was not the case in the early days of ICs when corporations
kept their trade secrets within the shores of their home countries, and government
technology export laws prohibited practices that would have required processing
knowledge and equipment to be located offshore in order to be successful. In the
1960s, it was companies like Fairchild, Clevite, Motorola, Texas Instruments, IBM,
Westinghouse, General Electric, et al, who were in fierce competition to dominate
the semiconductor...
 "Now that the government shutdown has ended,
CTIA is speaking up about its concerns with the National Defense Authorization Act
(NDAA) winding its way through Washington, D.C. For the most part, CTIA is happy
about the spectrum provisions in the One Big Beautiful Bill Act (OBBBA) that President
Trump signed on July 4. What's not to like? The OBBBA calls for
freeing up 800 megahertz of spectrum for commercial use over the next decade.
To kick things off, the FCC on Thursday will vote on a proposal that seeks comments
on how to auction at least 100 MHz - and possibly up to 180 MHz - of spectrum
in the 3.98-4.2 GHz band, aka the upper C-band..."
 Robert Balin created many quizzes for
Popular Electronics magazine back in the 1960s and 1970s. This particular
"Electronic Numbers Quiz" presents various objects and your challenge
is to match one of the provided numerical values to each item. For example, a tuning
fork is most commonly, in the Western world, associated with a certain frequency
for tuning musical instruments (electronic and mechanical). As is often the case,
being familiar with the "standards" of the era is helpful on a few of the items
like the tuning capacitor and the IF transformer, but you should be able to eliminate
some options by knowing the impedance of the twin lead transmission line and the
phase relationship of current and voltage in a pure inductance...
 Cloudfare, the Internet's guardian against
DDoS (Directed Denial of Service) attacks, was attacked early this morning, and
is still causing many major website to be inaccessible. The company is mum about
the cause. "In the last few minutes Cloudflare has confirmed it is aware of a major
issue affecting its Global Network, which is causing widespread internet outages
ranging from platforms like X (formerly Twitter) to ChatGPT, and, ironically, Downdetector.
A wave of other websites and services are also experiencing outages. After a large
spike at 11:45AM GMT (4,558 reports)..."
 This installment of "Stereo Scene" was the 12th in a series run by Popular Electronics
magazine in the early 1970s. As mentioned previously, stereo equipment was a big
deal in the 1960s and 1970s. Amazingly - or maybe not amazingly - some of the issues
of the day have persisted through today's audiophile community. One of the most
fervently debated topic is whether audio power amplifiers that use vacuum tubes
produce higher quality sound than do transistorized power amplifiers. The pro-tube
argument holds that the physical flow of electrons and the ability of metal internal
components to vibrate microscopically in response to signals imparts a quality to
the output that rigid semiconductors cannot. Many attempts at designing circuits
to artificially add such "quality" to transistorized amplifiers...
Monday the 17th
 A while back, I posted a couple of articles
on building simple
Tesla coils capable of producing a respectable electrical discharge arc. They
were completely passive devices and relatively safe. This Tesla coil design from
a 1959 issue of Electronics Illustrated magazine presents a model that
uses an 811A vacuum tube triode amplifier, and it can knock you on your posterior.
Believe it or not, 811A tubes are still readily available from many sources, including
eBay and DX Engineering, and are quite popular for RF amplifiers operating into
the HF band. This Tesla coil runs at 300 kHz rather than the 60 Hz AC
line current on the others. Author Harvey Pollack claims it will light a fluorescent
bulb from several feet away. A unique feature is a "tunable"...
 My grandfather, Roland (my middle name)
Somers, on my mother's side was a residential (aka house) builder. He owned and
operated a small (2-3 employees) business in Mayo, Maryland in the middle of the
last century. Being his only grandson, I got what survived of his books like this
Audel's Handy Book of Practical Electricity, c1942, by Theo. Audel &
Co. Publishers. I also have a couple of his carpentry and hand tool books of the
era. The scanned page below is entitled, "List of Abbreviations to Be Used
Radio Communication," as dictated by the International Radiotelegraphic Convention
(IRC). Amateur radio operators will recognize the list as being a collection of
the familiar "Q" Signals, although stated in sometimes archaic prose; e.g., QRN
= "Are the atmospherics strong?" and QSB = "Is my spark bad?...
 "China has developed a mobile high-power
microwave (HPM) air-defense system capable of disabling drones from nearly 2 miles
away in under a second. The system, called FK-4000 demonstrates how
microwave-based counter-drone technology is quietly becoming one of the most
transformative developments in modern warfare. Debuted at the massive Zhuhai Airshow,
the FK-4000 is designed to intercept even the smallest, lightest drones, which are
becoming increasingly difficult for traditional air-defense systems to detect or
shoot down. With drone swarms emerging as a major threat in future conflicts..."
 Carl and Jerry found the appearance and
construction of
2,400 megacycle transmitters and receivers to be quite odd compared
to the equipment they were used to dealing with. It's sometimes hard to believe
such an attitude of wonder when our world today is utterly filled with wireless
devices operating in the 2.4 GHz ISM band. Author John T. Frye could never
have imagined that such a reality would would exist half a century after his story
of the pair of teenage electronics sleuths. Unlike our postage stamp size integrated
assemblies that cost a few dollars, they speak of "special ultra-high-frequency
'light-house' tubes with a cavity resonator clamped on top of them." Back to the
story, though... Did you know that police were using radar guns as far back as 1963?...
 Television interference (TVI) was a major
concern for amateur radio operators back in the heyday of broadcast TV. Other than
radio broadcasts, magazines, and newspapers, it was the only other major form of
media available; there was no Internet. Even the lowest priced TV sets represented
a significant portion of a typical family's disposable income. There was no government
handout program that provided every household with a television set and antenna.
Consequently, people were very irritated by nearby electrical or electronic equipment
that dared to interfere with their reception - and rightly so. Ham radio operators
broadcast on bands that were fairly well separate from the TV channel frequencies;
however, harmonics and intermodulation products often fell in the TV bands, and
that caused real problems with the public perception of amateur radio. Articles
like this were aimed at helping people tame...
Reactel has become one of the industry leaders in the design and manufacture
of RF and microwave filters,
diplexers, and sub-assemblies. They offer the generally known tubular, LC, cavity,
and waveguide designs, as well as state of the art high performance suspended substrate
models. Through a continuous process of research and development, they have established
a full line of filters of filters of all types - lowpass, highpass, bandpass, bandstop,
diplexer, and more. Established in 1979. Please contact Reactel today to see how
they might help your project.
These archive pages are provided in order to make it easier for you to find items
that you remember seeing on the RF Cafe homepage. Of course probably the easiest
way to find anything on the website is to use the "Search
RF Cafe" box at the top of every page.
About RF Cafe.
Homepage Archive Pages
2026: Jan | Feb | Mar | Apr | May | Jun | Jul |
Aug | Sep | Oct | Nov | Dec
2025:
Jan |
Feb |
Mar |
Apr |
May |
Jun |
Jul |
Aug |
Sep |
Oct |
Nov |
Dec
2024:
Jan |
Feb |
Mar |
Apr |
May |
Jun |
Jul |
Aug |
Sep |
Oct |
Nov |
Dec
2023:
Jan |
Feb |
Mar |
Apr |
May |
Jun |
Jul |
Aug |
Sep |
Oct |
Nov |
Dec
2022:
Jan |
Feb |
Mar |
Apr |
May |
Jun |
Jul |
Aug |
Sep |
Oct |
Nov |
Dec
2021:
Jan |
Feb |
Mar |
Apr |
May |
Jun |
Jul |
Aug |
Sep |
Oct |
Nov |
Dec
2020:
Jan |
Feb |
Mar |
Apr |
May |
Jun |
Jul |
Aug |
Sep |
Oct |
Nov |
Dec
2019:
Jan |
Feb |
Mar |
Apr |
May |
Jun |
Jul |
Aug |
Sep |
Oct |
Nov |
Dec
2018:
Jan |
Feb |
Mar |
Apr |
May |
Jun |
Jul |
Aug |
Sep |
Oct |
Nov |
Dec
2017:
Jan | Feb |
Mar |
Apr |
May |
Jun |
Jul |
Aug |
Sep |
Oct |
Nov |
Dec
2016:
Jan | Feb |
Mar |
Apr |
May |
Jun |
Jul |
Aug |
Sep |
Oct |
Nov |
Dec
2015:
Jan | Feb |
Mar |
Apr |
May |
Jun |
Jul |
Aug | Sep |
Oct |
Nov |
Dec
2014:
Jan | Feb |
Mar |
Apr |
May |
Jun |
Jul |
Aug |
Sep |
Oct |
Nov |
Dec
2013:
Jan | Feb |
Mar |
Apr |
May |
Jun |
Jul |
Aug |
Sep |
Oct |
Nov |
Dec
2012: 1 |
2 | 3
| 4 | 5
| 6 | 7
| 8 | 9
| 10 | 11
| 12 | 13
(no archives before 2012)
- Christmas-themed
items
|
