|
 It is always nice to read an article that
encompasses more than one of my hobbies, whether it be amateur radio and amateur
astronomy like this one, amateur radio and model rocketry, or amateur radio and
radio controlled airplanes. I don't recall ever seeing an article that combined
astronomy and model airplanes. In this 1943 QST magazine piece, author
Hollis French expounds on the necessity for Hams to understand the effects that
atmospheric phenomena, caused primarily by our sun's periodic and intermittent
activity, have on radio signal propagation. Properties of the ionospheric layers
had by 1943 been pretty well surmised based on cause and effect relationships through
indirect observation since at the time no sounding rockets had been launched into
the upper atmosphere to obtain in situ measurements of ionization, magnetic fields,
and free electron activity...
 Maybe I suffer from cranial rectumitis at
the moment, but I'm having a hard time with a statement made about coaxial feedline
impedance, to wit, "102-ohm line (52-ohm lines in series)." I must be missing something
because I don't understand how placing two 52-ohm transmission cables in series
results in twice the impedance. Aside from that, author John Avery presents an interesting
article on
multi-impedance dipole antennas. Empirical data is presented on
how the feedpoint impedance of a dipole varies with distance above the ground. His
results are very close to theoretical values which assumes non-sagging elements,
perfectly linear alignment, a perfectly conductive ground, etc. He then extended
his investigation into 2-wire (4x impedance)...
 How well received do you think this social
concept would be in today's easily offended world: "To bring together socially the
Wives and Mothers of Dallas Radio Amateurs; to promote mutual
sympathy, counsel, and interest in our husband's and our son's hobby; and with a
realization that theirs is an outstanding, fascinating, far-reaching and educational
hobby, it is our desire to further their interests in whatever way may present itself."
It would be roundly criticized as a backward, misogynistic, 1930-era mindset intended
to subject women to yet another form of domestic slavery beyond housekeeping and
child rearing - no doubt thought up by a man. Anyone thinking so...
 This article reports on the very earliest
form of
voice mail - recording a message on a reel-to-reel tape deck,
placing it in an envelope, and snail mailing it to its recipient. Sure, it was slow,
but unless you were under surveillance for some suspected crime, there was just
about zero chance that some government agency was going to hear your private message.
I had forgotten about it until reading this, but I remember that back in the 1960s,
my father bought an el cheapo tape deck for our family and one for his parents,
who lived in Buffalo, New York. My parents and four sisters and I had a pretty good
time hamming it up on the tape, and looked forward to receiving a reply tape a month
or two later. "Grandpa B," as we kids called him, was a real funny guy...
 Welcome to the
RF Attenuator Quiz,
a technical resource specifically designed for engineers and radio hobbyists who
demand precision in their signal chain analysis. Whether you are troubleshooting
high-frequency systems, optimizing cascaded RF stages for improved impedance matching,
or developing custom measurement tools like RF Cascade Workbook, a thorough understanding
of passive attenuation is essential for maintaining signal integrity. This assessment
challenges your knowledge across ten critical areas, including power handling limits,
thermal derating, noise figure degradation, and the strategic use of attenuators
to enhance system IP3...
 If anything qualifies for meeting the criteria
of the old adage that says "Necessity is the mother of invention," it is
coaxial transmission cable. Wireless communications during World
War II was the necessity that drove the rapid development and continuous improvement
of coax. Other than materials technology for wire, dielectric, protective jacket,
etc., the basics of coax cable have not changed. It was during the war that polyethylene
was developed and adopted as a dielectric material much superior to previously used
copolene. Understanding of how electromagnetic fields propagate within and, under
non-ideal conditions - on the outside of the cable has increased significantly...
 If you are just starting out in the realm
of electronics or maybe just need a little freshening up of your
basic
math skills, this rather extensive article from a 1942 issue of QST
magazine is just what you need. Author Dawkins Espy does a really nice job of laying
out the basics of algebraic operations, Ohm's law, trigonometry, and logarithms.
Examples are provided for each category. In this day of calculators doing all the
hard work of calculating logs, antilogs, and trig functions, it does even seasoned
veterans at electronics calculations a bit of good to do a quick read-through to
knock off cobwebs in the gray matter. How long has it been since you have seen tables
of sine, cosine, and tangent values and/or tables of logarithms? Not long enough,
you say?
 Astronomers consider all elements heavier
than helium to be metals. That definition obviously does not jive with the standard
chemical definition of a metal as an element that readily conducts electricity,
but a concept called "metallicity"
argues that from a star (and therefore the universe) formation perspective, extremely
high temperatures and pressures in first generation stars (like our sun) preclude
the identification of distinct elements other than hydrogen and helium. Heavier
elements, such as lithium (#3 on the periodic chart and a major component in LiIon
batteries, is classified as a metal in chemistry) are overwhelmingly created after
a massive enough hydrogen star collapses and begins fusing H and He into heavier
elements. The relative abundance of hydrogen in the universe is deemed to be about
92%, and helium is 7.1%, so together they comprise about 99% of all elements...
 Amplifier Solutions Corporation (ASC) is
a manufacturer of amplifiers for commercial & military markets. ASC designs
and manufactures hybrid, surface mount flange, open carrier and connectorized amplifiers
for low, medium and high power applications using Gallium Nitride (GaN), Gallium
Arsenide (GaAs) and Silicon (Si) transistor technologies. ASC's thick film designs
operate in the frequency range of 300 kHz to 6 GHz. ASC offers thin film
designs that operate up to 20 GHz. ASC is located in an 8,000 sq.ft. facility
in the town of Telford, PA. We offer excellent customer support and take pride in
the ability to quickly react to evolving system design requirements.
 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...
 Transcat | Axiom Rental Equipment allows
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test equipment. They are committed to providing superior customer service and high
quality electronic test equipment. Transcat | Axiom offers customers several practical,
efficient, and cost effective solutions for their projects' TE needs and is committed
to providing superior customer service and high quality electronic test equipment.
For anyone seeking a way to offload surplus or obsolete equipment, they offer a
trade-in program or they will buy the equipment from you. Some vintage items are
available fully calibrated. Please check out Transcat | Axiom Rental Equipment today
- 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...
|
 • FCC Accelerates
Access to High-Speed Networks
• Low Power
360 Gbps Laser Wi-Fi
• Europe's
Electronics Sector Picks up Speed
• Top
5 Companies Granted U.S. Patents in 2025 (one American)
• Shape-Shifting
Semiconductors Activated by Light
 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 720-line HDTV display is made up of 1,280 vertical
lines and 720 horizontal lines of pixels, which gives a total of 921,600 pixels. A 1080-line
HDTV has 1,920 vertical lines and 1,080 horizontal lines, for a total of 2,073,600 pixels.
In 1969, a 230 vertical line by 230 horizontal line
electroluminescent (EL) flat-screen television display with 52,900 pseudo-pixels
was considered a big deal - and it was since it was the starting point for digital flat-screens
of today. Interestingly, while the "pixel" distribution was square, the actual display
retained the standard 4:3 aspect ratio, meaning horizontal element width was 33% greater
than the vertical element. Since each EL element was addressed individually, there was
no ability of a picture element to be shared by adjacent "pixels," so displaying a circle
would result in a very pixelated picture...
 A nice article by Donald Lancaster appeared
in an issue of Radio-Electronics magazine that introduces and puts into
layman's terms the relatively new (at the time) world of
digital logic circuits. Rapidly falling prices and equally
rapidly rising performance fuelled the craze. By 1969, most of the barriers
preventing former never-tubers from adopting the fledgling semiconductor
paradigm and there was by then a new generation of electronics hobbyists,
technicians, and engineers who had "grown up" on transistors and integrated
circuits. I like the author's analogies for AND gates and OR gates that involve
the familiar objects that include a garden hose with the house tap and nozzle,
and the kitchen sink faucet with the hot and cold handles. It's interesting how
often water, a substance generally to be avoided around electricity...
 The
APS-42, as described in this 1948 issue of Radio News magazine, was
truly a break-through x-band airborne search radar system born out of the lessons
learned from its predecessor: the APS-10 search radar developed during World War II.
This very compact radar system is contained within a volume of about 3 feet on a
side (not including the cockpit controls and displays. The close proximity of the
receiver front-end to the antenna made for a very low noise figure and, consequently,
high sensitivity. Interestingly, there is not a whole lot of information available
on the Internet for either radar. In fact, this article is probably the most information
source available on the APS-42...
 Radio-Electronics magazine for
a long time ran a "Radio-Electronics Monthly Review" column which reported on some
the major happenings in the industry. At the time, editors did not have instant
news availability like we have today via the Internet, so discovering items like
those included in this August 1946 issue required subscribing to news wire services,
receiving tips from readers and industry communications departments, reading multiple
newspapers and magazines, etc. Notable here is the recognition that amateur radio
hobbyists - aka
"Hams" - pioneered operation in the microwave realm of the electromagnetic spectrum.
Probably the most relevant story here, however, is the passing of John L. Baird,
aka "the father of television," who died on June 14th at his home in Sussex, England.
He was a relatively young 58 years old. In 1946, most people probably were familiar
with the names Marconi as" the father of radio," Morse as the inventor of his eponymous
code, Bell as the inventor of the telephone, Goddard as "the father of rocketry,"
etc., but I'm guessing not many associated the name "Baird" - or any other for that
matter - with television...
 2.1 GHz (5.6-inch, or 14 cm wavelength)
radio waves were an almost totally unexplored realm in 1930, with it and higher
frequencies being the domain of theoretical research laboratories. Signal generators
capable of producing much more than a few hundred megahertz were rare even in commercial
applications. As reported here, centimeter-length electromagnetic waves were "according
to the theories of Barkhausen and Kurz, [the] result of purely electronic vibrations,
whose frequency was determined only by the operative data of the tube and was not
dependent on any internal or external oscillation circuit." A half-wave receiving
antenna picked up the transmitted signal with a simple diode detector to enable,
after a couple stages of amplification, an audible signal. These are some of the
earliest experiments at radio frequencies (RF) with parabolic metallic reflectors
and polarization with a diffraction grid that could be rotated to set the polarization
direction...
 Byron Goodman published a very thorough
diode modulator
article in a 1953 issue of the American Radio Relay League's QST magazine.
It was one of the first of such articles that used the very recently available semiconductor
diodes rather than the previously used vacuum tubes. Single-balanced bridge and
ring modulator circuits are presented, along with the theory behind their operation.
It would be a few years more before double balanced mixers with their abilities
to reject even intermodulation products, and triple balanced mixers with very high
overall spurious product rejection, would become commonplace...
 Long before their college days at
Parvoo U., our two amateur electronics sleuthing buddies were on the job tracking
down and trapping bad guys by using their combined knowledge of circuits and
physics. In this episode,
Carl and Jerry are tasked with helping a hobby store owner stop a rash
of thefts that always seems to occur during a busy time right after school
lets out for the day. Their first inclination was to devise a system like
the big department stores were installing that used passive tags on items
that would trigger an indicator when passed through the detector at the exit
door. That was in 1958 when the anti-theft tags were first being utilized.
Unfortunately, the system they were able to build was not sensitive or selective
enough, so they came up with a different scheme...
 Leeds, which dubbed itself "The Home of
Radio," has been in New York since at least 1923. This advertisement appeared
in the December 1931 edition of QST magazine. Leeds is still in operation
today in Brooklyn under the name of Leeds Radio. They were one of the original "Radio
Row" companies. Looking at the ad is a step back ninety years into the past, but
the nostalgic waxing does not have to end there. If you want a trip back to the
beginning days of the World Wide Web, go to the current Leeds Radio website. It's
format-less text presentation with basic hyperlinks is circa 1992 when bulletin
boards ruled the day and the Mosaic browser was just giving web surfers their first
taste of a GUI. The only images I found on the Leeds website were a few scans of
old advertisements...
  RF
Cafe visitor Mike H. sent me these two photos of the same type Silvertone radio
as I discovered in Tony Packo's. He says there is no part number marked anywhere,
so its identity was still a mystery. Well, no more! I decided to use my paid subscription
to newspapers.com to search for an advertisement from an old newspaper. Sure enough,
there was a full-page advertisement by Sears, Roebuck, and Co., in the October 23,
1936 edition of the Rio Grande Farmer that appears to include this model.
Until proven otherwise, I hereby declare the
Tony Packo's radio to be the "7 Tube Silvertone Battery Console."
Battery powered radios were quite common in 1937 because commercial AC power distribution
lines did not extend to many rural locations, and many urban homes did not have
service, either. Lead-acid storage batteries powered...
 Common sense never goes out of style, especially
as it pertains to
safety in the presence of electricity. Most people who have worked in the electrical
/ electronics realm for a while are aware that lethal electrocution can occur with
currents as low as 100 mA when it passes through the heart. Lower values cause
progressively less profound maladies, but in practice any level of current great
enough to be felt is not a good thing. I have written before about having received
a few pretty scary shocks when working on high voltage equipment and many lesser
jolts throughout my 50± years of exposure. Other than observing my father's being
leery of using of anything with an electric cord attached to it, my first formal
instruction about electrical safety was in my vocational classes in high school.
Instructor Russ Lorenzen taught us to keep one hand in our pockets when working
on live circuits, which of course was only to be done under the rare circumstance
when it is not possible to first turn power off. In practice that often meant when
doing so would be more inconvenient than the calculated risk of electrocution. Seriously,
though...
 It has been a couple weeks since I last
posted any of the
electronics-themed comics which frequently appeared in the vintage trade magazines.
This sextet od comics came from the November and December 1961 issues of Radio-Electronics.
I particularly like the first one from page 99. It depicts a great The Three Stooges
type scenario. The comic from page 107 was ahead of its time in prognosticating
electronic one-armed bandit machines. You would need to be familiar with the days
of CRT televisions and the picture alignment process to fully appreciate the one
on page 108. Anyway, feel free to include any of these or the hundreds of others
linked at the bottom of the page in your next live presentation. They're a great
segue into your next spiel on project progress (or lack thereof) or design techniques...
 Mr. B. N. Slade, of the Tube Department
of Radio Corporation of America, wrote a series of articles on
transistor development for three 1952 issues of Radio & Television News
magazine. Consider that it was only four years earlier, a few days before Christmas,
that Messrs. Bardeen, Brattain, and Shockley announced their game-changing invention
of the point contact transistor. Already a plethora of commercial transistors were
on the market for incorporation into new electronic products. At the time, germanium
was still the semiconductor of choice, although silicon was gaining ground in laboratories.
This article covers the three basic transistor circuit topologies of common emitter,
common base, and common collector, which are analogous to vacuum tube circuits using
common cathode, common grid, and common plate topologies, respectively. Operation
up to around 200 MHz was obtainable...
 You might wonder why an article entitled
"Winning
the National Radio Control Meet" for model airplanes would appear in the ARRL's
QST magazine. The answer is that back in 1940 when it was published, a
Ham license was required to operate a radio control (R/C) transmitter. There were
no license-free bands for hobbyists as there are now. In fact, it wasn't until 1976
that the FCC suspended their requirement for registration as an operator, which
has returned in the form of an FAA "drone" (aka USAS) pilot directive. The author,
William E. Good, was the twin brother of Walter A. Good, both of whom held
doctoral degrees in and physics and Ham licenses, and were referred to as "the fathers
of radio control." The photo of Bill shows his station identification (W8IFD) displayed
on the transmitter enclosure, as required by the FCC. They were born in 1916 and
won the R/C championship in 1949, at the age of 33. In the early days, R/C operators
built (and often designed) their systems, including the electronics and mechanics.
They were the pioneers that took the figurative arrows while forging the frontiers
of this hobby. A couple notable items mentioned in the article are the needing a
QSA "5" level signal (the highest quality of reception) in order to assure reliable
control of the aircraft, and of how Hams helped advance the design of small internal
combustion engines. Also, Fig. 4 shows the rudder escapement located in the
vertical fin, with the wound rubber there as well...
 Here is the follow-up article from Phillip H.
Smith's original "Transmission Line Calculator" of his Smith Chart in the January
1939 issue of Electronics magazine. "An
Improved Transmission Line Calculator" appeared in the January 1944 issue. Mr. Smith
worked at the Radio Development Department of Bell Telephone Laboratories in New
York City. He states in part, "The calculator is, fundamentally, a special kind
of impedance coordinate system, mechanically arranged with respect to a set of movable
scales to portray the relationship of impedance at any point along a uniform open
wire or coaxial transmission line to the impedance at any other point and to the
several other electrical parameters. These other parameters are plotted as scales
along the radial arm and around the rim of the calculator, both of which are arranged
to be independently adjustable with respect to the main impedance coordinates."
A thorough discussion of the Smith chart's constructions and examples of its use
are presented...
 Back in my electronics technician days I
tried to get a job at a couple of the local hospitals as an on-site
equipment maintenance man. That was sometime in the early 1980s. Then, as now,
being a part of the healthcare system is a good way to assure job security since
it is a field that keeps growing with - even outpacing - population increases. Some
of the larger hospitals, similar to electronics design and manufacturing companies,
used to have their own test equipment repair and calibration departments, but most
of that is outsourced nowadays. This article from an 1972 issue of Popular Electronics
magazine highlighted some of the challenges that promised to make a career as a
medical equipment technician rewarding. You might also be interested... |
