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 Back in the 1960s, Electronics Illustrated
magazine ran a series of monthly Q&A columns titled "Electronic
Brain," where readers wrote in to query the staff on particular quandaries.
Even if you have been in the electronics game for decades, there were plenty of
questions that probably invoked the "I'm sure I could have answered that at some
point, but it's been so long that I couldn't say for sure," thought. The magnetomotive
force topic in this set of three items did it for me. I knew there was a magnetic
flux equivalent of electric current flow, but I probably would not have been able
to write the equation using the precise...
 We are accustomed these days with stores
having "no questions asked" return policies for just about anything. I once watched
a guy successfully return a 4" PVC plumbing fitting that had clearly been smeared
with glue in the coupling areas. Another time a guy returned a painting drop cloth
that was full of paint, declaring that it wasn't what he wanted. The return counter
bins of Walmart and other stores are always chock full of stuff. Such was not always
the case, though. This episode of
Mac's Radio Service Shop, mentions, among other thing, how busy
he and sidekick Barney had been right after Christmas doing troubleshooting and
repair on various electronic equipment that had been received as gifts. Imagine
receiving...
 San Francisco Circuits, a leading printed
circuit board fabrication and assembly supplier serving commercial and defense markets,
today announced that it has achieved Final
Cybersecurity Maturity Model Certification (CMMC) Level 2 Certification
status following a successful independent assessment by an accredited Certified
Third-Party Assessment Organization (C3PAO). San Francisco Circuits Achieves CMMC
Level 2 Certification The certification confirms that San Francisco Circuits'
enterprise information systems meet the cybersecurity requirements outlined in NIST
SP 800-171 Revision 2, as codified in 32 CFR Part 170, for the protection
of Controlled Unclassified Information (CUI)...
 Could this be the world's first publically documented rack-mounted AC power
strip? The
National
Company of Cambridge, Massachusetts, which began life as the National Toy Company,
ran a long series of advertisements in QST and other electronics magazines
that were heavy on text and light on pictures - definitely not the norm in advertising.
This one, number 62, from a 1939 issue describes, along with a reference frequency
oscillator, how their engineering team fabricated what we now call an AC power strip
for use in an equipment rack. According to the sketch provided, there does not appear
to be an On/Off switch and almost certainly not any form of surge protection as
is common (maybe even required by UL) for modern power strips. Someone at National
should have patented the idea; their heirs would be rich today...
 Presenting yourself or your company as being
modeled after a person of great accomplishment has been a common promotional tactic
for as long as there has been print media. The John Hancock chose in this issue
of The Saturday Evening Post to suggest, albeit by an indirect approach,
to elicit the admiration Americans had for
Thomas Edison's lust for innovation and desire to make people's
lives better in hopes that readers would associate Edison with the insurance company.
While the juxtaposition is strained, I do like one line in particular, "He lured
electricity into a bottle and taught it to glow with good cheer." This short tribute
to on of the world's greatest engineers is worth your a few moments of your valuable
time...
 Authors Cohen and Hessinger warn about the
need to consider the capacitive loading effects of shielded and closely-space test
leads when measuring other than direct current or very low audio or line frequencies.
Lead capacitance is especially likely to affect measured values
when the frequency is high and/or the source and load impedances are high. As was
common in the day, capacitance units of μμfd (micro-micro farads = 10-6
x 10-6 = 10-12 F) are cited, which is equivalent to units
of pF (10-12 F)...
 Welcome to the
RF Filter Quiz, an
essential tool for radio enthusiasts and engineers dedicated to mastering frequency
selectivity in complex signal chains. Whether you are troubleshooting signal interference,
optimizing stopband rejection for a sensitive receiver, or designing your own ladder
networks, a thorough understanding of passive and active filter synthesis is vital
for achieving peak performance. This assessment tests your knowledge across ten
fundamental concepts, including the practical trade-offs between Butterworth, Chebyshev,
and Elliptic topologies, the impact of finite component Q-factors, and the critical
relationship between group delay and passband ripple. By evaluating your grasp of
these core principles...
 Author Howard Wright takes the opportunity
here to distill the
concept of modulation down to its basic operation while dispensing
with the garbled mix of "graphs, formulas, charts, vectors, diagrams, and Greek
letters which often enter into various discussions of modulation". Wright describes
how to the uninitiated radio dial spinner, the culmination of events occurring behind
the scenes in an AM reception is akin to knowing "that, to be reproduced, the picture
[in a magazine] was broken down into its primary colors, if all we had to go by
was the original print and the magazine?" That is a very apt comparison...
 Here is a fairly major treatise on
folded and loaded antennas that appeared in a 1953 issue of
QST magazine, with "Suggestions for Mobile and Restricted-Space Radiators."
It is not for the faint of heart or anyone with mathphobia. Integral calculus is
part of the presentation, although an understanding of calculus is not required
to get the gist of the article. Equations for calculating the antenna configuration
radiation resistances are given for the 3λ/4-wave folded dipole, the λ/8-wave
folded monopole, the bottom-, center- and top-loaded λ/8-wave monopole, the bottom-loaded
λ/16-wave monopole, and the λ/4-wave monopole folded twice, to name...
 Kite- and balloon-lifted antennas are very
popular in the amateur radio realm. They are primarily used for short-term activity
such as during a contest or during an emergency; however, some operators use them
on a more extended basis. A really good series of articles on the use of balloons
and kites for suspending antennas can be found
here. Equations
for calculating necessary balloon and kite sizes and predicting wind effects are
included along with lists of "Dos" and "Don'ts." This is not a new phenomenon. A
1940 edition of QST magazine described how to employ weather and sounding
balloons to provide needed antenna configurations...
 New:
Frequency Planner. RF Cafe's spreadsheet-based engineering
and science calculator,
Espresso
Engineering Workbook™, is a collection of electrical engineering and physics
calculators for commonly needed design and problem solving work. The filter calculators
do not just amplitude, but also phase and group delay (hard to get outside of a
big $$$ simulator). It is an excellent tool for engineers, technicians, hobbyists,
and students. Equally excellent is that Espresso Engineering Workbook™ is provided
at no cost, compliments of my generous sponsors. 50 worksheets to date...
 Take a quick break before - or while - hunkering
down for a long day's grueling work. Most of the
electronics-themed comics that appeared in QST magazine
were associated directly with particular columns. For example, the cartoons featuring
"Jeeves," the overtaxed manservant of a never-seen house master, was part of the
"How's DX" feature. Drawn by artist Phil Glidersleeve (aka "Gil"), W1CJD, poor Jeeves
was often found doing his boss's will in the most precarious situation with intemperate
weather making his assignments tough to complete. Situations involving Podunk Hollow
Radio Club were frequent subjects of Gil's drawing pen as well...
 Somebody get Al Gore on the phone - preferably
using Skype. It appears that maybe he did not invent the Internet after all. Sci-fi
writer William F. Jenkins, who went by the pen name "Murray Leinster," wrote
a short story entitled A
Logic Named Joe, that appeared in March 1946 issue of Astounding Science Fiction.
In the story, an amazingly prescient description of the modern Internet is laid
out. The works is copyrighted so I will not replicate the entire thing here, but
these are a few excerpts that sound a lot like Mr. Leinster was in cahoots with
DARPA during the development*. Before I forget, thanks to RF Cafe visitor Terry
W. for sending the link. My comments look like...
 "Do you think that F.C.C. would be engaged
in the present terrific expense and effort of getting our fingerprints and citizenship
histories if there were intention of shutting us down shortly?" That statement was
printed by the QST magazine editor in the issue that preceded the December
7, 1941, attack on Pearl Harbor by thirteen months. A few things about it are troubling.
First, the FCC was
collecting fingerprints of licensed amateur radio operators. Second,
the FCC was assimilating information about licensed amateur radio operators' citizenship
histories. Third, a combination of short-sightedness and apparent naiveté concerning
the FCC's willingness to shut down amateur radio operations once...
 My introduction to a
tesseract was during an episode of Carl Sagan's "Cosmos" series
in the 1980s, where he was demonstrating how beings in of dimension N would perceive
items of dimension N+1. The tesseract, Sagan explained, is a 3-dimensional projection
of 4-dimension hypercube. Watch the embedded video for more information. The Tesseract
website, which has nothing to do with a hypercube as far as I can tell, deals in
some very cool antique scientific instruments. I learned of it from an article in
Astronomy magazine where an editor recommended it when researching the potential
value of a collectible telescope. Run by Drs. David and Yola Coffeen, Tesseract
has a huge inventory of items...
 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...
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360 Gbps Laser Wi-Fi
 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.
 It might be hard to believe that at one time
there was cabinet-level debate in government offices regarding whether FM radio
should be permitted to encroach on AM radio's well-established presence in the commercial
broadcast radio domain. When this 1951 Radio-Electronics magazine article
appeared, stereo was not even part of the contest since neither AM nor FM had implemented
it. The primary points of contention were cost to purchase and maintain a receiver
(AM wins) and consistency and quality of the sound over a broad range of frequencies
and amplitudes (FM wins). Some argued frequency drift would cause FM to need constant
re-tuning even with crystal control. Four months later, the February 1952 issue
of Radio-Electronics reported on the winner in an article entitled "xM
Wins in British Tests" (don't want to kill the suspense) for you...
 1934
was still riding the back of the high voltage craze popularized by Nikola Tesla
at the turn of the century. Super high voltage spark gap transmitters were still
being used in long distance communications for special applications. William Haight
was one of many people engaged in weather manipulation - both its creation and destruction.
Transportation, agriculture, and recreation would greatly benefit from the ability
to locally and temporarily control weather. This story of Mr. Haight's high-voltage
"electrodrome"
machine appeared in the May 1934 issue of Flying Aces magazine. Another
version of this electrodrome article by author Mel Wharton, entitled "Eliminating
the Peril of Fog," appeared in the April 1934 edition of Flying magazine.
There he says, "Repeated tests have shown that the operations of dispersing fog
is most effective at about 600,000 cycles - though work is done all the way on a
range from 500,000 to 1,500,000 cycles. The machine is capable of developing 500,000
volts, but only a fraction of this voltage is found necessary." A 4½ horsepower
gasoline engine-powered generator provides the voltage. A May 1935 issue of
Popular Mechanics magazine reports on Mr. Haight's electrodrome work...
 The effort to
block advertising on radio broadcasts has been going on for about
as long as advertising has been in use, as evidenced by this 1934 article in
Radio-Craft where a 'robot' advertising silencer' device is presented for removing
"superfluous advertising." Headlines from a few weeks ago announced Apple's program
for blocking ads that appear on websites, causing a big to-do about how all the
"free" content would be jeopardized since it is the advertisers who pay for the
music and other programming to be delivered to the user. Without the convenience
and economy of software to do the job in 1934, however, fairly complex discriminator
circuits were used to detect and mute the 'garrulous announcer or advertiser' between
regular programming. It's pretty funny to...
 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 since this article appeared in a 1946 issue of
QST magazine. 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 thanks for refined theory
and high speed computer simulations. RG-58 were early 50 Ω coax types, and
RG-59, RG-11, and RG-6 were early 75 Ω coax types that are all still in significant
use today...
 Following on the heels of the record-setting
demand for the January 1975 issue of Popular Electronics magazine (Part 1),
this February edition contains the second part of the
Altair 8800 Minicomputer article. The first article covered theory of operation
and constructions of the Altair 8800 Minicomputer, then the one introduces
the concept of computer programming. BASIC (Beginners' All-purpose Symbolic Instruction
Code) came about in the 1960's, but it was not until Altair BASIC (created by Microsoft)
hit the community in 1975 that it really started being used by a larger cadre of
programmers. It was for the Intel 8080 microprocessor, which the Altair 8800
used. Interestingly, BASIC is not referred to in this article; rather, machine language
code is demonstrated. The authors probably did so in order to emphasize the relationship
between the instructions being given and the actual machinations of the microprocessor
and logic circuitry...
 This custom made
Wireless Technology theme crossword puzzle from RF Cafe is for August 28th,
2022. "Across" words consisting of five or more letters begin with the first letter
of this puzzle's theme. All RF Cafe crossword puzzles are custom made by me,
Kirt Blattenberger, and have only words and clues related to RF, microwave, and
mm-wave engineering, optics, mathematics, chemistry, physics, and other technical
subjects. As always, this crossword puzzle 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., Reginald Denny or the Tunguska
event in Siberia). The technically inclined cruciverbalists amongst us will appreciate
the effort. Enjoy!
 This is the electronics market prediction for
Austria, circa 1966. It was part of a comprehensive assessment by
the editors of Electronics magazine of the state of commercial,
military, and consumer electronics at the end of 1965. Interesting is the
comment about Austria importing of computers to be leased to Communist countries
in Eastern Europe. It is not clear whether Austria was importing or producing
televisions. "Invest in Austria" is a contemporary website set up to promote
business in the country. Separate reports are included for West Germany, the
United Kingdom, France, Denmark, Austria, Sweden, Belgium, Switzerland...
 Credit for being the first to accomplish any notable
feat, whether in sports, medicine, science, aviation, etc., is constantly being challenged.
Some contestations are worthy of consideration based on documented facts, while others
can be readily dismissed as crockery. Gustave Whitehead, per anti-Wright Brothers zealots,
made the first powered airplane flight. The Vikings landed in America centuries prior
to Columbus - supposedly. Many stories have been written claiming that Dr. Mahlon Loomis,
a dentist, beat Guglielmo Marconi in the wireless communications race by using a system
of kites that took on a charge from overhead clouds. A keying device opened and closed
a conductive path to ground for effecting the Morse code...
 This table of conversions between various
forms of 2-port network electrical
parameters is difficult to find, so once I finally located a paper that included
them, I felt it was my duty to publish it for public access. The paper is available
on the IEEE website by subscribers only. Other have published the full paper without
permission of author Frickey. None that I found also include the correction paper
published a year later that addresses some of the technicalities of the S- and T-parameter
translations when complex impedance reference planes are used. In order to avoid
those sticky issues, I have reproduced only the sets of translations that are unaffected.
Many thanks to Mr. Frickey for his unique work. S-Parameters Y-Parameters Z-Parameters
h-Parameters ABCD-Parameters3 One of the most sought-after sets of conversion is
from s-parameters to T-parameters, and then back to s-parameters. This is because
matrix multiplications can be performed directly on T-parameters in order to calculate
cascaded component responses...
 Here are three
electronics-themed comics from vintage issues of Electronics World
and Popular Electronics magazines. My favorite is the page 84 comic
where the sign on the Telco Rectifier Components president's wall is apropos.
Maybe one of the interview questions for job applicants was #1: "Did you notice
the sign on the wall in the waiting room," and #2: "Did you 'get it?,' and
please explain." In 1956 when that comic appeared, AC-to-DC power supplies used
high voltage vacuum tubes, typically 300 volts or more. Hefty capacitors were
needed to remove enough ripple from the "top" of the DC to render it
undetectable in the circuit output - especially if the output was audio where a
60 or 120 Hz (50 or 100 Hz in Europe) "hum"...
 IC designers have been striving to make the
"ideal" opamp ever since the device type was first conceived. An ideal opamp has
a certain set of well-defined properties that permit it be used in circuits defined
by neat mathematical equations without the need for compensating or limiting terms.
An example of compensation might be having an input impedance of something other
than infinite ohms that causes a voltage division effect on the input voltage, and
a limitation would be a gain-bandwidth product that prevents it from being used
in high frequency applications. Opamps appeared in electronics before semiconductors
came onto the scene, and a couple companies attempted to market prepackaged vacuum
tube opamps that plugged into a standard octal kind of socket . EE120 at the University
of Vermont introduced me to operational amplifier theory...
 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...
 Take a look at the list of National Company's
employee list wishing their customers a
Merry Christmas and a Happy New Year. Every one of them is a licensed
Ham radio operator. It appeared in the January 1941 issue of QST, but
was for the 1940 Christmas. National Company was a major producer of amateur
radio gear in the day. Little did they suspect that by the same time a year
later, America would be newly engaged in World War II after the Japanese attack
on Pearl Harbor on December 7, 1941. Interestingly, the American Lung Society's
Christmas Seals stamp that appears in the upper left corner is authentic and
must have been applied by humans. That means thousands of copies had to be
manually stamped before mailing...
 Robert Taylor, along with inventing the concept
of "super-modulation," also coined the new communications term "Intelligence
Transmission Efficiency." It refers in part to the ratio of power in the intended
sideband relative to power in the at least partially suppressed other sideband and
carrier. Admittedly, I have not read this material enough to fully comprehend the
concept of super-modulation, but at least based on the Fig. 1 waveform, there
seems to be an element that adds a DC bias to the detected signal due to a nonsymmetrical
(about 0 Vdc) transmitter modulation by pumping more power into the positive peaks.
I'm happy to be corrected by any knowledgeable reader. For that matter, if you have
experience with super-modulation and care to share it with RF Cafe visitors, I'll
be glad to post your comments...
 This very large crossword puzzle will keep
you busy for a while. Since 2000, I have been creating custom
technology-themed crossword puzzles for the brain-exercising
benefit and pleasure of RF Cafe visitors who are fellow cruciverbalists. The
jury is out on whether or not this type of mental challenge helps keep your gray
matter from atrophying in old age, but it certainly helps maintain your
vocabulary and cognitive skills at all ages. A database of thousands of words
has been built up over the years and contains only clues and terms associated
with engineering, science, physical, astronomy, mathematics, chemistry, etc. You
will never find a word taxing your knowledge of a numbnut soap opera star or the
name of some obscure village in the Andes mountains. You might, however,
encounter the name of a movie star like Hedy Lamarr... |
