|
 A popular meme on chat websites these days
is the posting of some items or scenes indicative of times many moons ago, with
a comment something like, "If you know what this is, you are probably wearing reading
glasses." I recently saw one with a picture of an old cube type flash bulbs that
went on Kodak Instamatic cameras. In fact, I still have my Kodak Instamatic 40
camera and a couple of unused flashcubes. Those flashcubes were expensive for a
guy who never had much pocket cash; maybe that's why I have so few pictures from
back in the day. Anyway, I mention all that because some of the topics of these
electronics-themed comics from a 1962 issue of Electronics Illustrated
magazine would be likely candidates for the meme...
 A new word has been added to my personal lexicon:
"sphenoidal." Author John Kraus used it to describe the wedge shape
of a corner reflector. The Oxford Dictionary defines "sphenoid" thusly: "A compound
bone that forms the base of the cranium, behind the eye and below the front part
of the brain. It has two pairs of broad lateral 'wings' and a number of other projections,
and contains two air-filled sinuses." This "square corner" configuration - essentially
a "V" shape, is shown to exhibit up to 10 dB of gain while being relatively (compared
to a parabolic reflector) insensitive to physical size and driven radiator placement
across a wide band when made sufficiently large. No radiation pattern was...
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- and don't miss the blog articles!
 As you might know, particularly if you are
a frequent RF Cafe visitor, amateur radio operators (Hams)
were prohibited from broadcasting during the entirety of World War II,
(see
War
Comes) ostensibly as a security measure. The concern was that people
might unintentionally (or intentionally) convey information on troop positions and
family names, domestic factory locations and activities, and the general state of
the nation in regards to attitude and finance. Unlike today, that type of data was
not easily gathered even by a dedicated deployment of internal spies. In the early
1940s, the majority of amateur radio activity was carried out in the form of Morse
code, and operators were understandably concerned...
 Here is a fascinating story from a 1946
issue of the ARRL's QST magazine of the ordeal one Catholic priest
experienced while serving in the Philippines during the Japanese occupation in World
War II. Father Visintainer exploited his personal interest in
radio communications
to help keep local residents apprised of the war's progress and talk to the outside
world. Japanese troops confiscated all the existing shortwave radios and converted
them to their own frequencies. Some were re-converted by daring servicemen and then
hidden. Batteries were recharged using covert water wheel powered generators located
in the woods. Drama hit a peak one day when an attempt to formulate a make-shift
battery electrolyte resulted in an explosion that brought Japanese running to the
church lab...
 For decades, the engineering community has
viewed space as the ultimate frontier (Captain Kirk declared it) - a clean, vacuum-sealed
environment that offered a solution to the terrestrial limitations of bandwidth,
range, and latency. Nations and industries have long championed the
democratization of global communications, seeing Direct-to-Device (D2D) connectivity
as the next logical step in our technological evolution. But as we move from the
era of rare satellite backhaul to the age of the "mega-constellation," the engineering
paradigm has shifted. We are no longer just looking at the sky; we are beginning
to occupy it with such density that we risk creating a perpetual "noise floor" for
the rest of humanity. This article examines the thermodynamics, the mechanics of
orbital mesh nodes, and the sheer volume of material required to shift our compute
infrastructure into the heavens...
 Just the other day I saw a greeting card
with a sailboat on the front with the words "Anchors Away," on it. It was not meant
to be a pun on "anchors aweigh;" the card writer didn't know any better. This
episode of "Carl & Jerry" has our teenage Ham radio operators and electronics
hobbyists running a newly built model tugboat powered by a steam engine and navigated
via a radio control system. As is always the case, no activity of the pair goes
without drama of some sort. Author John T. Frye used his writings to present
technical topics within the storyline, both in the "Carl & Jerry" series here
in Popular Electronics magazine and his earlier "Mac's Radio Service Shop"
series that appeared...
 For the sake of all the avid cruciverbalists
amongst us, this
technical-term-themed
crossword puzzle contains only words and clues related to engineering, mathematics,
chemistry, physics, and other technical words. As always, this crossword contains
no names of politicians, mountain ranges, exotic foods or plants, movie stars, or
anything of the sort unless it/he/she is related to this puzzle's technology theme
(e.g., Hedy Lamarr or the Bikini Atoll)...
 Sam Benzacar, of Anatech Electronics, an
RF and microwave filter company, has published his May 2026 Newsletter that, along
with timely news items, features his short op-ed titled "The
Math of LEO No Longer Adds Up." Sam runs the numbers on Low-Earth-Orbit satellites,
and assesses future plans. "SpaceX now operates more than 10,000 Starlink satellites,
roughly two-thirds of everything in orbit. The next-largest operator, OneWeb, has
fewer than 700." They roam the nighttime sky, with small dots of light tracking
across our already light-polluted skies. The ITU coordination process now confronts
filings for more than a million LEO spacecraft, with half a million projected to
be in orbit by 2040. Now that Internet coverage and even Direct-to-Device (D2D)
networks...
 Meteor scatter communications is an excellent
example of where hobbyists - in this case amateur radio operators - have contributed
mightily to technology. It could be argued that a big part of the reason for such
occasions is that many people involved in science type hobbies are employed professionally
in a similar capacity, and their extracurricular activities are a natural extension
of what pays for the pastimes. It seems amazing to me that
meteor
scatter as a means of achieving upper atmosphere reflections of radio signals
went undiscovered until 1953, but evidently that is the case. Meteor scatter is
a very popular form of amateur radio challenge...
 "Make the most of your time at
Dayton Hamvention® with the free ARRL Events phone app. Hamvention is the world's
largest annual gathering of radio amateurs, and will be held May 15-17 in Xenia,
Ohio. There is a lot to do and see. Use the ARRL Events app to make sure you don't
miss a beat and plan out your visit now. The ARRL events app is produced by ARRL
The National Association® for Amateur Radio in partnership with Dayton Hamvention.
The app includes Hamvention's full program, so you can browse and schedule forums,
preview the extensive list of exhibitors, and find affiliated events. During the
event, attendees can use..."
 Here's a topic that never goes out of style.
Without bothering to worry about source and load impedances, this brief tutorial
on the fundamentals of
power supply filter design using series inductors and parallel
capacitor combinations. The author offers a rule-of-thumb type formula for guessing
at a good inductor value based on peak-to-average expected current. This is by no
means a comprehensive primer on power supply filter design and is directed more
toward someone new to the concept...
 Werbel's new
WMC-0.5-2-6dB-S, 6 dB directional coupler provides precision attenuation
where it matters most. It covers 500 MHz to 2 GHz with broadband flat coupling response,
high directivity, and excellent return loss performance. The device covers the upper
portion of the UHF band as well as L band in a single unit measuring just 3.60 x
0.60 x 0.38 inches. Minimized reflections increase accuracy of the measurement.
Mainline insertion loss of 1.2 dB (typical) includes coupling factor. The 6 dB coupling
ratio gives an approximate 75/25% splitting ratio and may be used as such to distribute
signals unequally where required, often to make up for asymmetrical losses elsewhere
in a system...
 Connecting a diode backwards across a solenoid
coil to shunt potentially damaging current and/or voltages when the supply is turned
off is a common trick for saving connected circuitry. Depending on the magnitude
of the magnetic field and how quickly the field collapses, some really high voltages
can be produced. In fact, the ignition coil and point (now
solid state) system in exploits exactly that principle to turn the 12 volts
from your car battery into 20-40 kV for firing the spark plugs. Engineers that
designed this early
cyclotron
had limited options for what to use given the state of the art in the early 1940s,
and chose to keep the generator permanently connected to the coil (no switch) so
that if the controller failed, the coil's energy...
 In the opening scene of "Gladiators," Quintus
remarks to Maximus (Russell Crowe), "A people should
know when they've been conquered." Such truth is applicable to society today regarding
ubiquitous surveillance. Less than two decades ago the media was
filled with stories of outrage over the discovery of some new form of monitoring
and reporting system having been installed on highways, in shopping malls, along
sidewalks, even bathrooms. Since the 9/11 terrorist attacks, anything goes with
government snooping. Count the numbers of freedoms you have lost and the inconveniences
suffered because of those 19 men with no identifiable common cause
(wouldn't want to profile). This story from 1956 shows
how long stealth installation...
 I wonder why today's editions of the ARRL's
QST magazine does not have a column dedicated to the "YL" (Young Lady,
or female in general) contingent of the amateur radio realm? Ham radio, as most
-if not all - historically male-dominated hobbies has fairly significant outreach
efforts to try attracting women into activities. My Model Aviation magazine
has a monthly column written by a lady whose enthusiasm for model airplanes equals
that of most males - and she's funny to boot! - but it is not dedicated to female
modelers. If there is a girl or woman present at a competition, she is almost guaranteed
to receive coverage...
 The December 1947 issue of Radio News
and the February 1954 issue of Radio & Television News published these
electronics-themed comics. Humor evolves over time, which is apparent when you
look over these and many of the other comics from these vintage electronics magazines.
The AVC comic is the best, IMHO. For those of you not around in the olden days of
vacuum tubes, tapping on a tube would often make it work properly again, either
because of a dirty contact in the socket or crud that had accumulated on the screen
grid. I give this batch a score of about 7 out of 10, but you might think otherwise.
There is a growing list of other comics at the bottom of the page. Enjoy...
 How RF circuits work have long been referred
to as "black magic,... even sometimes by people who fully understand
the theory behind the craft. To me the ways in which a transmission line - be it
coaxial cable, microstrip, or waveguide - can be manipulated and controlled with
various combinations of lengths and terminations is what most qualifies as "magic."
Sure, I know the equations and understand (mostly) what's happening with incident
and reflected waves, etc., and how the impedance and admittance circles of a Smith
chart graphically trace out what's happening, but you have to admit there's something
wonderfully mystical about it all...
 I remember hearing a long time ago about
"The Thing"
- a passive bugging device discovered within a wooden Great Seal gifted to the U.S.
Embassy in Moscow. This 1962 Electronics Illustrated magazine feature explores
the ingenious, battery-less Soviet listening device. Far from a conventional electronic
bug, this passive device utilized a specialized resonant cavity and a diaphragm
that modulated an external 1600 MHz radio beam, essentially acting as an echo-based
microphone that was incredibly difficult to detect. While the article highlights
the device's diabolical simplicity and sensitivity, it contains no mention of the
U-2 incident or Gary Powers; notably, historical records clarify that Ambassador
Lodge displayed the device in 1960 to expose Soviet espionage...
 Based on beleaguered wife Sylvia Kohler's
mention of GE's Electronics Park in this story (surely a fable... or not), she and
unintentional antagonist, superheterodyne hubby (aka "Happy Boy," but we know him
as Popular Electronics cartoonist
Carl Kohler) probably lived in the Syracuse, NY, area. Electronics
Park existed during the hey days of General Electric when the sprawling campus ,
just north of I-90, designed and manufactured a plethora of both household and military
electronics products. GE's Electronics Laboratory ("E-Labs") was the company's pride
and joy. Today, a tiny portion of Electronics Park is still occupied by Lockheed
Martin, who bought that GE division in the 1990s, and the rest belongs the city.
But I digress... enjoy the story (her reason for referring to hubby as a Superheterodyne
is highlighted)...
 Multielement quad antennas are as popular
today as they were in 1967 when this article appeared in the ARRL's QST
magazine. That is not to say they are common. This particular design is for the
10-, 15-, and 20-meters bands, all three
of which are still in use today. If you build a multielement quad as shown here,
you might want to find a substitute for the bamboo frame members; aluminum tubing
is pretty cheap, but if you use metal, you'll need to use insulators at the connection
points. Formulas are provided for determining element lengths and director and reflector...
 There is something about these proposed
shorthand circuit symbols that reminds me of the IEEE digital
logic symbols using the distinctive shape (the traditional format) versus the newer
rectangular shape format. The set is quite extensive when all the different flavors
of combinatorial blocks - flip-flops, timers, counters, shift registers, encoders,
decoders, etc. - are included. My personal preference, you might guess, is the original
format with distinctive shapes. Although I do not do a lot of digital work, it is
easier for me to follow the signal flow and mentally perform the logic operations
with the distinctive shapes. But I digress. This article from a 1947 issue of
QST magazine introduces...
|
 • Europe's
Electronics Sector Picks up Speed
• Top
5 Companies Granted U.S. Patents in 2025 (one American)
• Shape-Shifting
Semiconductors Activated by Light
• UK Teachers Say
AI Eroding Critical Thinking
• FCC
Approves Charter's $34.5B Acquisition of Cox
 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.
 The name
Ernst Frederick Werner Alexanderson (1878-1975) might not seem
overly familiar to you, but he is credited with designing the first high frequency
alternator for transmitting longwave audio modulation over long distances. His device
preceded the spark and arc type transmitters that infamously spewed harmonics and
noise all over the spectrum and were therefore a great nuisance when broadcast at
high power levels. It was a relatively (for the time) narrowband scheme that permitted
more stations to be co-located in a given service area. He went on the develop one
of the first successful television projectors as well. Read a short biography on
Mr. Alexanderson in the "Men Who...
 Frequent RF Cafe visitor who goes by the
moniker "Unknown Engineer" sent me a hyperlink to a PDF file on Amazon's CloudFront*
content delivery network (CDN - basically a file server) that contains no fewer
than 17 amazing radar and vacuum tube related line
drawings
published by Varian Associates' TWT Division, Palo Alto Tube Division, Solid
State Division, Eastern Tube Division, Western Tube Division, Solid State West Division.
These highly detailed and busy drawings were done around 1975 by British illustrator/artist
C.E.B. Bernard; a search for his works did not reveal much. The events shown are
fictitious, as are the accompanying hand-printed stories. Some of the puns are pretty
clever, but are somewhat dated for today's readers. To wit, the name Memamadun Ptolemy,
which for the uninitiated is an allusion to the movie "Blues in the Night," where
the actual words are "My momma done 'tol me..." (get it?). Another worthy mention
is, "Tube V or not Tube V, that is the question," an obvious play on Shakespeare's
"To be or not to be, that is the question" line by Prince Hamlet. If you recognize
those, you'll find other familiar takeoffs as well...
 All three questions in the May 1964
Radio-Electronics magazine "What's
Your EQ?" challenge should not be too difficult for most RF Cafe visitors. EQ,
by the way, stands for "Electronics Quotient." For the first one, you might want
to make use of the Delta-Wye converter in the newly released (and free) Espresso
Engineering Workbook™. With the Voltage Divider, don't bother trying to write multiple
equations in multiple unknowns. By inspection you can deduce what the voltage drop
across the 2.5 kΩ resistor are, then knowing that the current through all resistors
is the same, figure out the required values of R1 and R3. Finally, sum all the resistances
and multiply by the current. Done. I have to admit to not getting the Doodle answer.
If I had time, I'd do the oscilloscope thing to verify the author's solution...
 Building speaker enclosures was a popular
project for stereo enthusiasts in the 1969 time period when this article appeared
in Radio-Electronics magazine. Lots of well-designed speakers were commercially
available, but they tended to be expensive. High-end speaker enclosures typically
had high-end speakers within, which contributed to the increased cost. I built a
pair of wooden enclosures while in the USAF at Robins AFB, Georgia. It had
a very nice woodshop. The speaker cabinets had a very simple internal design; the
removable front frame was the hardest part to build. Mine were made from pine. For
my level of music appreciation, I found that a quality set of car speakers provided
great sound for all but the deepest bass frequencies. An added advantage was that
the crossover circuit was built in, so all I needed was to build a crossover to
split the really low frequencies to 10" bass speakers that were purchased at Radio
Shack . The Radio Shack crossover circuits were too high (1 kHz) so I found
an article showing how to build one that split at around 500 Hz; admittedly,
it didn't work very well. The grille cloth also came from Radio Shack...
 In today's throw-away society, most people
would never consider attempting to
repair a loudspeaker if it were to develop a tear or a puncture. Why should
you bother when a replacement is so inexpensive? Well, there are few reasons you
might want to affect the repair yourself. First, the speaker might be integrated
into the system in such a manner that replacing it would be difficult or even impossible.
Second, some speakers are actually pretty darn expensive, especially large diameter
models and high quality models regardless of size. Third, a replacement might not
be available, as with a vintage radio or television. Fourth, maybe you just want
the challenge and satisfaction of repairing the speaker rather than adding its bulk
to a landfill. This article from a 1955 issue of Popular Electronics magazine
offers a short tutorial on loudspeaker repairs. It was written before foam cones
became available, but adapting other repair media and adhesive for foam should not
be a big barrier to undertaking such a task. Be sure to choose a glue type that
exhibits some flexibility once cured, which means standard cyanoacrylate (CA / superglue)
would probably be a poor choice. Special formulations for bonding foam are available
and should work well...
 Imagine if you wanted to transmit from your
car with a 400 kHz radio and had to trail a
600-foot-long ¼-wave wire antenna behind to do it. Of course nobody ever did
that, but it was common practice with airplanes in the days before VHF and UHF communications
became the norm. It wasn't because nobody knew that it would be more advantageous
to operate at higher frequencies in order to reduce antenna size requirements, it
was that electronic equipment capable of withstanding the rigorous environment of
airborne conditions was not ready for prime time, as the saying goes. Come to think
of it, the term "prime time" had probably not even been coined yet when this article
was written in 1946 because it derives from the evening television viewing hours
(~8:00 to 11:00 pm) when the most viewers were tuned in. Electric and/or manual
winches were used to deploy the antenna after getting airborne and to reel it in
prior to landing. Weights were hung on the end in order to prevent oscillations,
but that was dangerous both to the aircraft and people and objects on the ground
when a length of wire and the weight...
 There does not seem to be anything particularly
stand-out-ish about the
Wells-Gardner Series 062 automotive superheterodyne radio. As was typical of
car radios in 1932 when this Radio Service Data Sheet appeared in Radio-Craft
magazine, the main electronics was housed in a chassis that got mounted in the trunk
or under a seat, and the controls either got mounted in or under the dashboard,
connecting tot he electronics via a cable. The "eliminator" option of the "eliminator
or battery" label presumably refers to an AC-to-DC power supply that can be used
either during maintenance or if the listener chooses to employ the radio in use
outside of a vehicle - or else has a very long extension cord ;-) No examples of
surviving Wells-Gardner Series 062 automotive radios could be found anywhere online.
As with all these radio data service pages, this one is posted for the benefit of
both researchers and for restoration types who need troubleshooting and alignment
information...
 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
80 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. In other
news, the editors report on a scheme to use a remote-controlled airplane, signaled
by a
Tesla spark gap transmitter, to drop bombs inside tornados in
order to break up and stop their...
 It was a lot of work, but I finally finished
a version of the "RF &
Electronics Schematic & Block Diagram Symbols"" that works well with Microsoft
Office™ programs Word™, Excel™, and Power Point™. This is an equivalent of the extensive
set of amplifier, mixer, filter, switch, connector, waveguide, digital, analog,
antenna, and other commonly used symbols for system block diagrams and schematics
created for Visio™. Each of the 1,000+ symbols was exported individually from Visio
in the EMF file format, then imported into Word on a Drawing Canvas. The EMF format
allows an image to be scaled up or down without becoming pixelated, so all the shapes
can be resized in a document and still look good. The imported symbols can also
be UnGrouped into their original constituent parts for editing...
Hugo Gernsback, as I have often pointed out, had a penchant for predicting technology
development and user trends. Decades of researching and publishing articles and
books, inventing electrical and mechanical devices, and creating educational material
enabled a synergistic combination of real-world experience and visionary thinking.
In this 1945 Radio-Craft magazine editorial entitled, "The Radio Alarm," Mr. Gernsback envisioned a form of public
emergency broadcast system that would notify the public of impending and/or in-process
dangers like natural and man-caused disasters, invading armed forces, police alerts,
etc. His idea involved incorporating a special always-on circuit into radios that
would listen for a broadcast tone and then switch the radio on automatically. Of
course in 1945 there would need to be a minute of two allotted for the tubes to
warm up before sending out the actual message. In 1951 the CONELRAD system was put
into operation to alert citizens in the even of a Cold War era invasion or attack,
doing exactly what Gernsback had envisioned, albeit without a the special turn-on
circuit. Then, in 1963 the more familiar Emergency Broadcast System (EBS) took over...
 After reading both this article and "The
Sarasota Mystery First Follow-Up" article in the April 1966 issue of Popular
Electronics, I'm convinced that the inventor Wallace Minto either did not understand
the phenomenon he describes, or he's out to punk the reader. If this initial article
had been printed in the April issue rather than March, it almost certainly would have
to have been a Fool's scam. Minto believes he has discovered a new form of electromagnetic
propagation that exploits molecular / atomic properties of water to transmit the signal
- without attenuation and without picking up noise. If it sounds too good to be
true...
 Here is a good quiz on calculating total
equivalent capacitance for circuits containing various combination of series,
parallel, and series-parallel connections. It appeared in the June 1968 issue of
Popular Electronics magazine. To help in calculation, all of the individual
capacitor values are the same. Many of them you can probably solve in your head,
especially if you mentally rearrange the circuit into a more readily recognizable
configuration. For instance, circuit #1 can be redrawn having two parallel branches
across the source. One branch has just a single capacitor while the other has two
parallel capacitors in series with one capacitor. The equation is then C + (2C2/3C)
= C + 2/3C = 5/3C. For C = 6 pF, Ctotal = 5/3*6 pF = 10 pF... Friday 17
 Dang, I swapped two answers and scored an
80%. Haste makes waste, as the saying goes. Don't rush through this 1967 Popular
Electronics "Electronic Angle Quiz" like I did and you'll probably ace it with
the greatest of ease - especially if you have been in the electronics realm at least
since the 1980s. Generation X'ers can have a two-question handicap (might never
have seen real-life example of drawing "A" or "E") and Millennials (might never
have seen drawing "A," "B," "D," or "H") get a four-question handicap...
 Whether you are new to the subject of noise
figure or are just looking for a quick review, this "Hot
and Cold Resistors as UHF Noise Sources" article in a 1976 issue of QST
magazine is a good source. Author Benjamin Lowe, K4VOW, does a nice job of explaining
the concept of electrical noise, and then presenting equations governing the calculation
of noise factor and noise figure. Actual numerical examples are provided to demonstrate
how the formulas work. Using this method, you can make a fair measurement of
the noise figure of a receiver without the need for expensive test equipment.
 According to Samuel Milbourne's "Battery
Types and Their Characteristics" article in Popular Electronics magazine,
in 1973 there were about 400 different battery types to choose from when deciding
what to buy for your automobile, electronic device, uninterruptible power supply,
flashlight, etc. I don't know what the number of types is today, but it must be
in the thousands. Nominal voltage, case size and shape, energy capacity (amp-hour
rating), current delivery capacity ("C" rating), environmental accommodation, connection
type (contact, solder, screw-on, or push-on terminals), chemistry, number of recharge
cycles (for secondary batteries), and a host of other choices are available nowadays.
Every time I need to order a new Li-Po battery pack for a model airplane or helicopter,
I spend quite a bit of time searching through mAh versus weight and physical size
specifications to identify the best - and most affordable - option. There will never
be a one-size-fits-all battery. If you are interested in vintage batteries... |
