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 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...
 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.
 A few days ago I posted a webpage detailing
my work to generate equations for gain, phase, and group delay for a Butterworth
lowpass filter, using the basic polynomials. I could not find them anywhere on the
Web or in filter design books I own. The only difference between calculating Butterworth
lowpass, highpass, bandpass, and bandstop filter values for gain, phase, and group
delay is how the relative frequency is defined. Simply substitute the following
for ω in any of the equations for gain, phase, or group delay. It's that simple.
Graphs are published below. Frequency units cancel out, so a 1 Hz cutoff plots
the same as a 1 kHz cutoff or a 1 GHz cutoff for gain and phase. The group
delay scale needs to be divided by a factor equal to the frequency units (÷103 for
kHz, ÷106 for MHz, etc.)...
 This "Recent Developments in Electronics"
from a 1960 issue of Electronics World had a lot of
antenna news that included a retarded surface wave antenna with high gain and
low silhouette for use in airborne early warning radar as well as ground based and
shipboard radar, a pair of 60-foot tropospheric scatter antennas that are specially
mounted at opposite ends of a 180-mile long section of the Gulf of Mexico, and a
104-foot-long rotating 50-ton radar antenna used for the SAGE early warning system.
Also reported was Westinghouse Electric's airborne Stratovision for broadcasting
educational television programming to rural areas out of reach of existing
towers...
 Light-emitting diodes (LED's) were still relatively
new to the scene of solid state electronics in 1969 when this article was published in
Electronics World Magazine. Two engineers from RCA Electronic Components wrote
to describe the state of the art in LED physics and features. The pair's prediction that
the LED would become "a light source that can be used for indication and display wherever
tungsten-filament, incandescent lamps are used" did not yet have enough insight into
the devices to know that four decades would pass before their prediction would be realized.
LED's have...
 Time to put on the thinking cap again for
three more "What's
Your EQ?" circuit challenges, compliments of Radio-Electronics magazine
in May 1962. The first is a classic "black box" type problem which, from reading
its description, involves some sort of resonant circuit. that's all I'll say on
that. The next, called "An Easy One?" should, by the way it is drawn, be a clue
that it might be easier to solve if you re-draw it to make a familiar-looking circuit.
Hint: Summons the spirit of Sir Charles Wheatstone. Just the name of the last one,
"Iterative Network," is enough to induce a cold sweat. As with most of these "What's
Your EQ?" problems, successful completion of a first year college circuits course
is plenty to get through them. A few are better attempted by people with hands-on
experience troubleshooting circuits, but don't let that scare you off...
 Have I mentioned that my YL, Melanie, decided
she would earn her Amateur radio Technician license? After living in a household
with a bilingual husband (English and Electronics) for nearly 38 years and having
become fairly proficient at ETL (electronics as a third language*), Melanie decided
to earn her Technician license. She has never delved into the technical aspects
of electricity / electronics, but because of hearing me speak of it (too) often
and having proof-read my writings and scanned and OCR'ed more than a thousand articles
from vintage electronics magazines, her gray cells are permeated with the vocabulary,
lingo, jargon, vernacular, slang, and argot of the realm. Being an expert test taker,
she will undoubtedly pass the written test with flying colors. With much self-restraint,
I have avoided offering my sage advice and knowledge during her studies of the ARRL's
Ham Radio License Manual. The current edition is the 4th, being valid from
2018 through 2022. Melanie has asked for a little clarification on SWR, decibels
and couple other minor topics, but otherwise has progressed...
 For a long time, I have been scanning and
posting Radio Service Data Sheets like this one featuring the
Emerson Model AZ-196 (Chassis AZ) tabletop radio. It appeared in the August
1938 issue of Radio-Craft magazine. There are still many people who restore and
service these vintage radios, and often it can be difficult or impossible to find
schematics and/or tuning information. Back in the day, both service shops and do-it-yourselfers
relied on these documents for making repairs and tweaking the performance since
manufacturers would not make the information available to anyone other than an authorized
dealer. A nicely restored example of the Emerson Model AZ-196 can be seen at the
left. A running list of all data sheets is at the bottom of the page to facilitate
a search.
 When this
Standardized Wiring Diagram Symbols & Color Codes feature appeared in a
1956 issue of Popular Electronics magazine, semiconductors were just coming into
common use. Therefore, only the simplest components like a diode and bipolar junction
transistor (BJT) are included. In fact, the only two types of diodes shown are vacuum
tube and selenium. The semiconductor diode is labeled as a crystal rectifier. There
is no light emitting diode (LED), field effect transistor (FET), metal oxide semiconductor
FET (MOSFET), integrated circuit (IC), or other commonly used modern device. Note
also that the "Receptacle 117V" does not show a safety ground connection. The "Vibrator"
was a device commonly used to convert direct current (DC) to alternating current
(AC). About the only people who will find a use for this information are those who
service and/or restore vintage electronic equipment...
 Found in what is the first issue of
Electronics Illustrated magazine that I have bought are these Amateur radio
related comics entitled, "Over
and Out." The cartoonist's signature is simply "Rodrigues," which according
to a Google search might be Charles Rodrigues (who also contributed to other tech
magazines as well as to National Lampoon). I have to admit to needing to
look up the "Yanqui aggressors" thing on the one comic, and then it made sense:
Yanqui= Yankee. The last comic with the parrot is pretty funny; it's sort of the
Ham radio equivalent to an auto-repeat telephone dialer like what you would use
to call into a radio show during a listener contest...
 It took me a couple passes of the explanation
to comprehend the advantage of a Thomson-Varley (aka Kelvin-Varley, since Thomson
and Lord Kelvin are one and the same person)
switchable voltage divider compared to a standard type. At first I thought the
author, Edwin Bohr, was implying that the source and load impedances would not have
as great of an effect on the accuracy of the divider (and to some extent it is less
sensitive), but the main advantage is that the configuration permits simple cascading
stages of decade dividers to achieve essentially any degree of resolution. Both
a standard series-wired type voltage divider and the Thomson-Varley need ten resistors...
 Dr. Lee DeForest might have had something
like National Public Radio (est. 1970) in mind when he penned this article in 1933.
In it, the famous vacuum tube amplifier inventor lamented and criticized the commercialization
of broadcasts because of all the paid product announcements (aka commercials) that
had been steadily increasing over the years. He also was critical of the "hit-or-miss,
higgeldy-piggeldy mélange program basis" of programing; i.e., the same station playing
a mix of jazz, opera, swing, syndicated story-telling, etc. The good doctor did
not elaborate on where funding for such dedicated, uncorrupted broadcasts would
originate if not from paying advertisers, and I do not recall ever reading about
a DeForest Radio Network paid for by his vast fortune. I don't like commercials
any more than the next person, but a company deserves time to pitch its products
and/or services if it helps deliver a source of entertainment to you that...
 RF Cafe visitor Jeff B. of Beverly, MA, sent
me these photos of his
General Electric Model M-49, 4-tube radio-phonograph, dual-wave superheterodyne set
that he is going to restore to working order. It appears to be in extremely nice condition
for a 1930s era unit. He found the Radio Service Data Sheet from a January 1935 issue
Radio-Craft magazine that I posted back in October 2016. These are now
the only images of the M-49 anywhere I can find on the Internet...
 For the sake of avid cruciverbalists amongst
us, each week I create a new
crossword puzzle that has a theme related to RF, microwave, electrical and mechanical
engineering, mathematics, chemistry, physics, astronomy, mathematics, and other
technical words. 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, find someone or something in the otherwise excluded list directly related
to this puzzle's technology theme, such as Hedy Lamarr or the Bikini Atoll, respectively...
 I
have never been a fan of "free verse" poetry,
be it in the form of a sonnet or otherwise.
In my humble opinion,
poems that do not both rhyme
and have some measure of meter
represent laziness on the part of the "poet."
Without requiring poetry to rhyme,
all that is required to declare anything a poem
is to break the writing into poem-like lines,
et voilà - you have a poem.
It is like slinging a brush-load of paint
onto a canvas and calling it art.
Example -- I hereby proclaim the above to be a poem because I broke it into separate
lines - see what I mean? That ain't no poem; we both know it.
I will excuse the following example since it was written by a Ham about
Amateur Radio
- although most of its lines do actually rhyme...
 RF Cafe visitor Mike M. sent this very
interesting note after reading this "Frequency
Modulation Fundamentals" article: Again, you hit it out of the ballpark, Kirt!
Great article out of QST. Absolutely accurate to credit "The Old Man" Edwin Armstrong
for the invention/development of FM and much more, plus the work of Dan Noble, who
worked with the Connecticut State Police and Motorola as Director of Research. Also
many, many others. Some that have never been properly credited. Guys like Bob Morris,
W2LV and Frank Gunther, W2ALS. They were both interviewed by Ken Burns for "Empire
of the Air". I was fortunate enough to talk to both of these guys after I got my
Tech license in 1970. My immediate supervisor/mentor from 1972 until he retired
in ~1990, was George. He was a superb mentor, who espoused the best engineering
methods and as he would say " the price of success is constant vigilance." George
had worked for Armstrong at the pioneering FM station, W2XMN in the late 40's and
early 50's. George had several stories about working for "The Old Man..."
 By 1945 everyone of importance in the electronics
industry was blowing the figurative horn of television. The country would transform
from "a chicken in every pot" to "a
TV in every living room" (OK, I just made that up). The NTSC (National Television
System Committee) had set the standards for transmission, but hardware implementation
was by no means agreed upon. If my memory is correct, there were still some manufacturers
clinging to the mechanical spinning disc with a projection screen rather than using
electronic circuits and a CRT (cathode ray tube). Entire industries - not only electronics
- were bursting at the seams in anticipation of the war ending and being allowed
to release all the pent up knowledge and inventions developed during the years working
toward the defeat of Axis powers across the globe being applied to creature comforts
for the civilian marketplace. Television, with its countless dependents and dependencies,
truly changed the planet. Some say for the better, others say for the worse... |
