See Page 1 |
2 |
3 |
4 | of the February 2024 homepage archives. Wednesday the 21st
 Once World War II was over, a flood
of technical information poured out of government, academic, and corporate research
and manufacturing institutions. Making available such data was a promise made by
the Department of War to a citizenry which largely supported the wartime effort
to maximize resource usage for defeating Axis powers. People and businesses provided
raw and recyclable materials as well as services in the interest of assuring our
fighting men had every tool at their disposal while fighting for the folks back
home. To today's unpatriotic and selfish population it might seem like a Pollyanna
and even unlikely view of the world, but that was the case back in the day. Bell
Telephone Laboratories (aka Bell Labs) contributed Big League (not "bigly," as ignoramuses
claim Trump said) to the pushing forward of technical frontiers. A major development
was use of waveguide for microwave systems like radar. As mentioned in this 1947
Popular Mechanics magazine infomercial, their engineers had already figured
out how to not only transport radio frequency signals within the confines of
waveguide...
 Here's a great bit of TVI (television interference)
sleuthing for you, as told by RF Cafe visitor Andrew B. "A customer called me with
a strange issue, back in the analogue transmission days (UHF). Twice a day at roughly
the same time [12 hours apart], BBC channels would completely disappear, only to
reappear around 30-45 minutes later. I replaced the antenna, the cable, even the
chimney bracket and pole, but nothing fixed the issue. I then arranged with the
customer to be on the roof at the time that the issue usually happened. I plugged
my meter into the aerial and waited. Sure enough, the SNR shot up and as it did
I looked around to see what it could be. Luckily I noticed something from my excellent
viewpoint on the ridge next to the chimney! We have a tidal river called the
River Severn, and twice
a day we get a bore wave
as the water rises and recedes. The transmitter was on the other side of this river,
around 40 miles away. I then read about how reflections could cause ghosting due
to multipathing, and in some cases caused complete loss of desired signal, and how
a stacked array could solve these issues. Long story short, using the horizontal
stack method, we managed to eliminate the issue completely!"
 When I read this installment of Mac's Service
Shop, in the March 1972 issue of Popular Electronics magazine, the first
thing that came to mind was my own experience with
television interference (TVI) when I was a kid. In that case, the transmitter
of my radio control system for a model airplane was the culprit. The frequencies
and channels are almost exactly the same as reported in this infodrama™. In
the 1970s, citizen band (CB) radios operated in the 27 MHz realm, as did my
R/C transmitter. During summer vacation from junior high and high school, I would
run my model airplanes up and down the street in front of my house, getting up just
enough speed to lift off and then immediately chopping the throttle and landing.
As soon as the transmitter was switched on, nearby housewives would lean out their
doors and yell at me for screwing up "As the World Turns" or "All My Children."
They were not particularly happy with noise from the engine, either. I eventually
adjusted my operation times to avoid the afternoon soap opera prime time...
 Ever since the manned space
exploration programs began at NASA (National Aeronautics and Space Administration),
controversy over both the financial costs and the cost in lost opportunity for other
government funded programs has existed. Many people, myself included, have always
championed the efforts and believe the axiom of the whole being greater than the
sum of the parts applies to the efforts. Opponents say resources would be better
spent here on Earth. In fact, we have always done both. To address the issue,
NASA Spinoff
was created to publicize the byproducts of the space program that benefit other
areas of research, manufacturing, and society. Since at least the 1970s, NASA has
published a monthly magazine entitled
NASA Tech Briefs
to inform the public on their activities, inviting readers to submit ideas and to
request information on how to apply NASA research to commercial applications. I
have been a regular reader since around 1980.
 What stood out to me when reading this 1974
Popular Electronics magazine article on
walkie-talkies is a statement made near the end where the author claims regarding
loaded whip antennas, "Transmit losses are many times greater than receiver losses."
The last time I checked, passive antennas are reciprocal devices, so gains and losses
should be the same for transmit and receive. Maybe he meant that for a given antenna
loss value in decibels, that the absolute power loss is greater at the transmitter
end. My main reason for posting the article is because it pretty much completes
the evolution cycle of walkie-talkies, which started life being called handie-talkies
when being developed during World War II as lightweight, portable 2-way radios
which could be deployed in regions of difficult travel and even carried by paratroopers.
Nowadays, most "serious" handheld transceivers operate in the 462-467 MHz Family
Radio Service (FRS) band, rather than in the 27 MHz Citizens Band as did early
models...
 With more than 1000
custom-built stencils, this has got to be the most comprehensive set of
Visio Stencils
available for RF, analog, and digital system and schematic drawings! Every stencil
symbol has been built to fit proportionally on the included A-, B-, and C-size drawing
page templates (or use your own page if preferred). Components are provided for
system block diagrams, conceptual drawings, schematics, test equipment, racks, and
more. Page templates are provided with a preset scale (changeable) for a good presentation
that can incorporate all provided symbols...
Tuesday the 20th
 Here is yet more evidence of my oft-made
claim that Germany might have dominated the world as a technological and financial
superpower if it had not instigated two world wars. A huge amount of ingenuity and
ability to convert ideas into reality has come out of Germany over the course of
centuries. Oppressive and often inhumane government behavior caused a lot of that
talent to emigrate to other countries, so the opportunity was lost. In this instance,
I refer to
Julius Edgar Lilienfeld, who not only produced the first sample of liquefied
helium, but also is credited, according to this 1964 Radio-Electronics
magazine article, for developing the first semiconductor devices for amplification.
U.S. patent number US1745175A was awarded on January 28, 1930 (filed on October
8, 1926) for what was essentially a field effect transistor. Lilienfeld became a
U.S. citizen in 1935. To be fair, I will also note that many of those fled-to countries
are today as bad or worse than Germany was then...
 "By better taming the Jekyll-and-Hyde nature
of an
alternative to the semiconductor - one that transitions from electricity-resisting
insulator to current-conducting metal - Nebraska's Xia Hong and colleagues may have
unlocked a new path to smaller, more efficient digital devices. The team reports
its findings in the journal Nature Communications. The semiconductor's ability to
conduct electricity in the Goldilocks zone - poorer than a metal, better than an
insulator - positioned it as the just-right choice for engineers looking to build
transistors, the tiny on-off switches that encode the 1s and 0s of binary. Apply
some voltage to the control knob known as a gate insulator, and the semiconductor
channel allows electric current to flow (1); remove it, and that flow ceases (0).
Millions of those nanoscopic, semiconductor-based transistors now coat modern microchips,
switching on and off to collectively process or store data. But as minuscule as
the transistors already are, the demands of consumers and competition continue pushing
electrical engineers to shrink them even further, either for the sake of squeezing
in more functionality or downsizing..."
 A score of 80% is nothing to brag about,
but at least I got all the easy ones right. A couple of them I guessed at based
on how the circuit looks - like the one with the "gimmick" coupling. This quiz by
Popular Electronics magazine quizmaster Robert P. Balin tests your
knowledge of
coupling circuits. If it had not been for studying for my Ham radio license
tests, I would not have recognized the gamma matching circuit. Fewer and fewer people
nowadays - at least as a percentage of those engaged in electronics - are familiar
with fundamental concepts of circuit design (truthfully, I've forgotten a lot of
what I learned decades ago). Entire products can be designed nowadays using just
integrated circuits, a handful of power supply decoupling capacitors, and maybe
a little software code...
 I admit that the main reason I'm posting
this is because of the cool looking hand-wound isolation transformers. With all
the pre-made, integrated components and assemblies that are the rule these days,
it's nice to see such an exception. You will find this a lot with designers and
builders of RF transmitter circuits. This one happens to be for a DC power supply.
It begins: "Electrical
isolation is defined as the separation between two circuits that will restrict
the direct current and any unwanted alternating current in a power supply. One of
the main reasons that a circuit may need isolation is to protect it from damaging
or dangerous currents and/or voltages. Isolation will also prevent dangerous voltages
from passing to the operator during an electrical fault/failure or lightning
surge. However, the flow of AC current transfer of power and signal will still be
able to flow between two circuit system areas. This article describes some various
application examples that need isolation. Here are only a few general examples:
Protecting human operators and low-voltage circuitry from high voltages. Improving
noise immunity. Handling ground potential differences between communicating subsystems.
Now let's get down to some of the key areas that use isolation..."
 Here are a couple more tech-themed comics
from vintage Popular Electronics magazines. Only one comic appeared in
each of the May 1972 and July 1972 issues, so I combined them onto a single page.
What's that guy in the May comic in the background doing? Anyone remember those
pieces of furniture that were once a staple of engineering offices? I spent many
an hour sitting at such drafting tables drawing schematics and block diagrams as
an electronics technician. By the time I earned my BSEE, everyone was using computer
CAD software, albeit still rather crude by today's standards. The July comic reminds
me of a scenario that might have appeared in one of the old
Calvin and Hobbes comic strips that graced our newspapers up through the end
of 1995. Calvin's father, in case you didn't know, was a patent attorney...
 Banner Ads are rotated in all locations
on the page! RF Cafe typically receives 8,000-15,000 visits each
weekday. RF Cafe
is a favorite of engineers, technicians, hobbyists, and students all over the world.
With more than 17,000 pages in the Google search index, RF Cafe returns in
favorable positions on many types of key searches, both for text and images.
Your Banner Ads are displayed on average 280,000 times per year! New content
is added on a daily basis, which keeps the major search engines interested enough
to spider it multiple times each day. Items added on the homepage often can be found
in a Google search within a few hours of being posted. If you need your company
news to be seen, RF Cafe is the place to be...
Monday the 19th
 When reading this article about a 50-foot-diameter
inflatable radar antenna dome from a 1949 issue of Popular Science
magazine, I was surprised to learn it was only rated for withstanding 2 inches of
snow. The story says snow or ice, but 2 inches of ice would typically weigh an lot
more than 2 inches of snow - even wet snow. That is not to say it cannot survive
in regions where more than 2 inches of snow is likely to fall. It cleverly uses
a repetition of partial deflation / inflation actions to flex the surface, thereby
causing the snow and/or ice to lose its grip and slide off. That sounds good in
theory, but I wonder how successful it really was under real-world conditions. If
you do an Internet search on some of those huge inflated sports arena domes in snowy
locales, you'll find plenty which collapsed under heavy snow loads. That happened
to the Erie Sports Arena when we lived there.
 "Odysseus continues to be in excellent health,
and flight controllers are preparing planned trajectory correction maneuvers to
prepare the lander for lunar orbit insertion. Since the
IM-1 Mission launched on SpaceX's
Falcon 9 rocket, flight controllers on the Company's red, white, and blue teams
have been learning more about the lander and how to efficiently fly the mission
to return the United States to the surface of the Moon..."Some people celebrate
the transfer of responsibility for manned and unmanned space exploration vehicles
to private contractors, citing lower costs and competition. You cannot convince
me that the true cost of any given private contractor system is any less than a
NASA project, especially given duplications of efforts and indirect payments outside
of the formal contract. Fortunately, many of the private companies are doing an
excellent job, but I'd rather see "NASA" painted on the side.
 Is it permissible to say, "Pig Latin,"
these days without being jailed for engaging in hate speech or being accused of
cultural insensitivity? ...not that I really care.
Carl Kohler's/ story from the November 1966 issue of Popular Electronics
magazine had me waxing nostalgic over a similar scenario from my own boyhood. It
begins with Mrs. Kohler (aka "Goodwife") suggesting that she and Mr. Kohler
resort to speaking in Pig Latin in order to prevent their mischievous sons
from learning where the Christmas presents were being hidden. My parents did exactly
the same thing to my sisters and me - and that was in the 1960's. My older sister,
Gayle, and I made a point of learning Pig Latin ourselves in order to thwart the
evil scheme. By the next Christmas we were able to discern that a certain corner
of the attic was the secret hiding place. Our rancher style house's attic was not
very big, but then neither were we at the time. We anxiously awaited the evening
shortly before Christmas when our parents went to the holiday party put on by the
local kids' sporting association, and had those pull-down stairs opened almost before
the car got out of the driveway...
  Since it was established in 1979, Reactel
has become one of the industry leaders in the design and manufacture of RF and microwave
filters, diplexers, and sub-assemblies. Company president
Jim Assurian's pride in his resident state of Maryland (my home
state) is apparent in his company's promotions, and even his attire! From Reactel's
LinkedIn feed: "Here is one of the many
filters shipping from Reactel, Incorporated this week. Today,
we are featuring a UHF-Band Discrete Component Diplexer intended for low-frequency
communication applications. We manufacture RF, Microwave & Millimeter Wave Filters,
Multiplexers and Multifunction Assemblies up to 67 GHz and can design a unit to
fit your specific application..."
 Engineering and science magazines, websites,
and discussion panels frequently report on and lament the lack of women and minorities
in both realms. You might think this is a relatively new concern since, but as evidenced
by this 1972 Popular Electronics magazine tidbit the effort to attract
women and minorities into the fields has been going on for half a century. At
the time, women and minorities made up about 2% of undergraduates in engineering
curricula. The proportion was 20% as of 2015 (a 10x increase) according to a recent
report by the American Society for Engineering Education (ASEE). During that same
time period (1970), according to the National Center for Education Statistics the
overall split between men and women in college (in the U.S.) was 4,249,702 3 males
and 3,118,942 females (57% males / 43% females). As of 2105 the split was 7,499,837
males and 9,536,941 females (44% males / 56% females). The ratio has reversed and
today favors women to the degree it favored men in 1970. That must be why there
are so many government programs now which are attempting to get men back into college.
Oh, wait, no there's not...
Sunday the 18th
 This custom RF Cafe
electronics-themed crossword puzzle for February 18th contains only clues and
terms associated with engineering, science, physical, astronomy, mathematics, chemistry,
etc., which I have built up over more than two decades. Being the 18th day, words
containing the letter "R" are marked with an asterisk (*). Many new words and company
names have been added that had not even been added to the world's technical lexicon
when I started in the year 2002. 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. You might,
however, encounter the name of a movie star like Hedy Lamarr or a geographical location
like Tunguska, Russia, for reasons which, if you don't already know, might surprise
you. The technically inclined cruciverbalists amongst us will appreciate the effort.
A full list of all RF Cafe crosswords is at the page bottom. Enjoy!
Friday the 16th
 Evidently I am in good company with my appreciation
for good humor related to science and technology. This "Cartoons
Teach Physics with a Smile" article appearing in the June 1948 issue of
Popular Science magazine cites the College of the City of New York's Professor
Robert S. Shaw's use of such hilarity in his physics classes. Whereas the artists
who created these comics probably did not intend to illustrate a particular physics
principle, many people familiar with the principles are quick to recognize what
is going on. As can be seen in the hundreds of electronics and technically themed
comics on the pages linked at the bottom of the page, those which showed up in publications
like Radio and Television News, Short Wave Craft, Radio-Electronics,
QST, and Popular Electronics were specifically created for the
type audience that reads them. BTW, I learned a new word here: isostasy. An unrelated
story that occupied the other half of one of the pages reports on a problem telephone
cable stringers had with gophers chewing through the insulation - definitely not
funny at the time to the engineers, but kind of funny in retrospect...
 Brigadier General David Sarnoff's name was
well known to most people in the realm of communications up to the time of his death
in 1971. His technical and leadership skills were recognized and rewarded throughout
his very accomplished lifetime in both military and civilian venues. This brief
biography of Sarnoff was printed in the March 1972 issue of Popular Electronics
magazine. Born in Russia and brought to America at age 9 by his parents, he, at
17, began his career working as an operator at the Marconi wireless station at Saisconset
on Nantucket Island (on duty when the Titanic sank). As with many people of high
acclaim, he had a few run-ins with other notable people during his career - the
most famous of which was the Battle of the Airwaves fought between Edwin Armstrong
and him over FM versus AM broadcasting...
 "MXene-coated devices can guide microwaves
in space and lighten payloads. One of the most important components of satellites
that enable telecommunication is the waveguide, which is a metal tube for guiding
radio waves. It is also one of the heaviest payloads satellites carry into orbit.
As with all space technology, reducing weight means reducing the amount of expensive
and greenhouse gas-producing fuel it takes to launch a rocket, or increasing the
number of devices carried by the same rocket to space. Researchers from Drexel University
and the University of British Columbia are trying to lighten the load by creating
and testing a waveguide made from 3D-printed polymers coated with a conductive nanomaterial
called MXene. In their paper recently published in the journal Materials Today,
the group reported on the potential of using MXene coatings to impart lightweight
nonconductive components with electrical conductivity - a property sacrificed in
additive manufacturing using polymer materials, such as plastics. "In spaceflight
applications, every extra gram of weight counts," said Yury Gogotsi, PhD, Distinguished
University and Bach Professor in Drexel's College of Engineering, who is a leader
in MXene research. "MXene materials provide one of the thinnest possible coatings
- their flakes have a thickness of a few atoms - that can create a conductive surface,
so we see great potential in using MXenes to treat additive manufactured components
made of polymers that have complex shapes."
 This type of
electronic pollution is not e-waste as you think of today, but electrical noise
pollution. Ever-rising ambient noise floor levels have been an issue since the inception
of wireless electronics. In excess, it can render both analog and digital circuits
useless, or at best annoying to use. Addressed in the 1973 Popular Electronics magazine
article are the phenomenon of unintentional heterodyning and signal to noise ratio
degradation, from both natural and man-made sources. Author Garrison touches on
the intentional generation of noise for electronic warfare applications. I did a
quick Internet search looking for plots of typical background ambient electromagnetic
noise levels in an urban environment for today and from the middle of the last century
(~1950), but with no success. If not for spread spectrum technologies that can operate
reliably at S/N ratios less than one, however, many forms of communications would
be next to impossible...
Thursday the 15th
 Did you know that the name "Walkie-Talkie"
was created by U.S. soldiers using them in the field? That's, according to Galvin
Manufacturing Corporation, who developed the first "Handi-Talkie"
in 1933. Galvin, in case you don't know, was the original name of Motorola. Founder
Paul Galvin started out making "battery eliminators" for DC (direct current) radio
sets, and then created / filled a need for radios in automobiles. Motorola is yet
another example of a portmanteau, which combined "motor" and the "ola" suffix of
Victrola (a sound reproducing device). This 1943 Life magazine promotion by Motorola
is typical of what appeared in many household magazines as a means of garnering
support both for the war effort and for the company's products. During World War II,
many manufacturers were compelled to convert some or even all of their facilities
over to production of military materials...
 From IEEE
Spectrum: "Happy birthday, IBM! You're 100 years old! Or are you? It's true that
the businesses that formed IBM began in the late 1800s. But it's also true that
a birth occurred in February 1924, with the renaming of the Computing-Tabulating-Recording
Co. as the International Business
Machines Corp. And a hundred years after that event, it serves as an important
reminder that the world of computing and IT that IBM played a pivotal role in building
has a longer history than we are likely to think. 'Data processing' was coined over
a century ago, while 'office appliance' was in use in the 1880s. From the 19th century,
through the 20th, and into the 21st, IBM was there, making HP, Microsoft, and Apple
appear more like children or grandchildren of the IT world. So let's take a moment
to contemplate the origins of an iconic corporation. Back in the late 19th century,
as the U.S. economy gave birth to important large enterprises - telecommunications,
railroads, manufacturing - the need to coordinate the work of individuals and dispersed
locations led to the mechanization of information. Hence the emergence of typewriters,
adding machines, and cash registers. Time-recording devices tracked when workers
arrived and left..."
 This is not the first time I have learned
a new word when reading an episode of
Mac's
Radio Service Shop. "Calumny," is the word-du-jour for entry into my personal
lexicon. It is not necessarily a technical word, but definitely one I shall attempt
to incorporate in future writings. Calumny is "a misrepresentation intended to harm
another's reputation" per Merriam-Webster. ...but I digress. In this December 1949
issue of Radio & Television News magazine, a customer and fishing buddy
of Mac's, each of whom is a small business owner, drops in at the repair shop to
look for Christmas gifts for the family, but is evidently put off a bit by the prices.
Mac turns it around on him by reminding him how most proprietors like them operate
on small profit margins and rely on volume, and therefore long works hours to make
a decent living. It is as true today as it was in 1949. Upon reading the entire
article, it appears as though John Frye has his Roget's Thesaurus nearby while writing
this piece...
 Ernest Werbel, founder and president of
Werbel Microwave, announced on their LinkedIn page, "We can now
laser mark directly onto the parts! No more ugly labels that can *schmear* and
peel off. Less costly and time-consuming than screen printing. Contact us if you
are interested in having your parts marked!" Since 2014, Werbel Microwave has designed
and produced high performance radio frequency components for military, commercial,
test and measurement applications. Werbel Microwave welcomes customers to submit
their customized RF requirements for quotation. Werbel Microwave also welcomes distributors
and resellers. Orders placed online typically ship within 24 hours. We have expanded
in-house engineering capabilities to support and maintain product design with minimal
end-of-life risk...
 The April 1973 issue of Popular Electronics
magazine concentrated on antennas for everything from citizens band (CB) radios
to televisions and amateur radio. This particular article covers a compact,
multi-band Ham antenna with a minimal level of skill and components required.
Construction and tuning tips are offered. It includes the popular 10-, 15-, 20-,
40-, and 80-meter bands. Standing wave ratio (SWR) plots are shown for all four
bands. If I had time, it would be interesting to enter the dimensions into EZNEC
(now free) to see what kind of performance it predicts...
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. I also
have an extensive list of
Recently Added topics.
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