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 Back in the days when I built a lot of prototype
electronic gear, project enclosures were generically referred as a "Bud
Box." Lab stock rooms always had a good variety of sizes and configurations
of the soft aluminum and sometimes plastic boxes that were easily drilled, punched,
filed, and painted to make professional looking equipment. Not all the project boxes
were made by Bud Industries, but just as everyone knows you're talking about
a cola when you say "Coke," it was understood that a "Bud Box" was a chassis for
a home-brewed circuit. They are still seen in construction articles of electronics
hobby magazines today. I have even seen test equipment and utility items for sale
that are obviously in a Bud Box type of chassis. This full-page advertisement for
Bud Radio appeared in a 1930 issue of Radio Craft magazine - a mere two years after
opening their doors...
 This week's crossword puzzle sports a radar
and radio 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 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...
 The
traveling-wave tube (TWT), invented by Dr. Rudolph Kompfner during World War
II, revolutionized microwave amplification by providing exceptional bandwidth without
the limitations of traditional resonant cavities. By utilizing an electron gun,
a precision-wound helix, and a magnetic focusing circuit, the TWT transfers energy
from an electron beam to a propagating signal wave. This design enables high-gain,
low-noise performance essential for radar, missile guidance, and high-capacity telecommunications
systems like the TH radio-relay. Although early production faced challenges regarding
reliability and manufacturing complexity, ongoing engineering refinements achieved
the stability necessary for critical applications, including the Telstar communications
satellite...
 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)...
 An old electrician's saying goes "Ground is ground the world around," implying that every point
on Earth's surface is at the same potential - specifically 0 volts. We know, of
course, that it is not so. Maybe on average such a claim could be made, but just
as "sea level" is not the same at all points on the ocean's surface (hence we speak
of "mean sea level"), neither is the voltage potential the same everywhere. Further,
just as the salinity of all points on the ocean surface do not have the same salinity
(and thereby conductivity), the conductivity of various places on dry land vary
- often significantly. Electric power systems are very concerned with soil electrical
conductivity in the vicinity of power generation installations...
 Byron Goodman published a very thorough
diode
modulator article in a 1953 issue of 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...
 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...
|
 • China Loses Monopoly over
Rarest of Rare Earths
• Samsung
Memory Chip Worker Union Strike Averted
• AI
Glasses Shipments Grow 322% in 2025
• ChatGPT
Solves Elusive Geometry Proof
• Elecraft
Donates Radio Station to W1AW
 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.
 Every time I see one of these articles on
"modern"
medial electronics it makes me think of the Star Trek IV movie titled, "The
Voyage Home," wherein Dr. McCoy (aka "Bones") intervenes as a 20th century brain
surgeon is about to operate on Chekov - "My God man, drilling holes in his head
is not the answer!" The 1948-vintage electrocardiograph featured in this Radio-Craft
magazine article looks like it was built from parts salvaged from World War II
field gear. Having a doctor attach wires to you is scary enough, but back when the
probes were powered by instruments using circuits with 200-300 volts of plate
bias in them would add an extra level of anxiety. BTW, have you ever wondered how
"star dates" in Star Trek were determined? As it turns out, the system has not been
consistent throughout the series from television and the movies then back to television.
It began as a random number to avoid needing to specify a particular century...
 This
is a Javascript calculator for
fixed Pi and T attenuators. Enter values for Rin, Rout, and Attenuation, then
click Calculate. If unequal termination resistances are used and an attenuation
value is selected that is lower than what is physically possible (a negative resistor
value is displayed), then a message will appear in the box over the schematics.
"k" is the linear ratio equivalent to the decibel value of the attenuator. Equations
used in this calculator can be found on the Pi and Tee Attenuators Equations page...
 It is no secret that I consider Hugo Gernsback to have been one of the last century's
premier technology innovators, futurists, and publishers. Many of his proposals,
prognostications, predictions, forecasts, and maybe even prophecies came to fruition
in his lifetime - often due to his own efforts. In the case of the
burgeoning wireless entertainment industry (radio and television), Gernsback
commented on the contention between household members over which program should
be tuned in. To wit from a 1960 issue of Radio-Electronics magazine: "Yes,
a family may conceivably have two separate radios and three TV sets, each in a different
room - everyone has seen such split households - but we must all agree that this
is an asinine and not very progressive solution to the problem, even if sufficient
rooms are available. It won't prevail in the future." This didn't really happen
until the availability of smartphones and wideband streaming video, so sometime
around 2008 - about six decades later...
 It is doubtful
that as many people today build their own
stereo speaker enclosures as was the case
back in the 1950s through about the 1970s. During those decades stereo equipment
was a really big deal, as evidenced by the large number of articles in technical
and hobby magazines. I have posted a couple dozen articles on the subject here on
RF Cafe. Topics included equipment reviews and feature comparisons, troubleshooting
and alignment, modifications to commercial units, build-it-yourself projects, optimized
room layout and construction, and even advice on how to best enjoy your stereo system.
Lots of comics appeared in the magazines as well poking fun at how a stereo enthusiast's
family members and neighbor might not appreciate the ear drum-busting power capability
of your system. There were also quizzes like this one on speaker enclosure baffle
design...
 You probably won't find too many people
stacking television antennas these days, but many Hams still do
it. Vertical stacking is used primarily to increase overall gain without appreciably
altering the azimuth beam, while horizontal stacking forms a tighter azimuth beam
without appreciably affecting the overall gain. When it comes to optimizing antenna
designs installations for operations below about a gigahertz, Amateur Radio practitioners
have pretty much written the book on the subject - actually, they have written hundreds
of books on the subject. Antenna stacking is often used...
 A few years ago I posted a note about a technical
faux pas on an episode of Star Trek titled "Court Martial," where Captain Kirk makes
a comment ordering the ship's auditory sensors to be boosted "on the order of
1 to the 4th power," (14) in order to pick up heart
beats. RF Cafe visitor Sam M. just sent me a note offering a possible - and
plausible - explanation for the gaff. If you are a devoted Trekkie looking for a
response to your apostate friends when confronted over the scene, read on...
 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 225,000 times per year! New content
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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...
 This custom RF Cafe
electronics-themed crossword puzzle for July 9th contains words and clues which
pertain exclusively to the subjects of electronics, science, physics, mechanics,
engineering, power distribution, astronomy, chemistry, etc. If you do see names
of people or places, they are intimately related to the aforementioned areas of
study. Being that "I" is the 9th letter of the alphabet, it is used as the first
and/or last letter of many words in today's crossword puzzle - as well as in-between.
Those clues are marked with an asterisk (*). As always, you will find no references
to numbnut movie stars or fashion designers. Need more crossword RF Cafe puzzles?
A list at the bottom of the page links to hundreds of them dating back to the year
2000. Enjoy.
 The January 2016 issue of Scientific
American ran an article by Clara Moskowitz titled "Elegant Equations" that presented
a few prints from "The Concinnitas Project" which "...is a collection of ten aquatints
produced from the contributions of ten mathematicians and physicists in response
to the prompt to transcribe their 'most beautiful mathematical expression.'" The
renowned mathematicians and scientists who contributed to the project are Michael
Atiyah, Enrico Bombieri, Simon Donaldson, Freeman Dyson, Murray Gell-Mann, Richard
Karp, Peter Lax, David Mumford, Stephen Smale, and Steven Weinberg. My personal
favorite is "Ampère's Law," by Simon Donaldson, because it incorporates a simple
line drawing along with the familiar equations. It brings back memories of sitting
in electromagnetics class at the University of Vermont watching my seriously brilliant
professor...
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 225,000 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...
 It should come as no surprise that in the
pre-safety-ground era which included the 1960s that electrical shocks of patients
in hospitals was not uncommon. If the jolt came intentionally from a cardiac defibrillator,
then it would be a good thing. However, these shocks, which were the subject of a
Time magazine story in the April 18th, 1969 issue cited by Mac's technician, Barney,
were being administered unintentionally by patient monitoring and ancillary life-sustaining
equipment. Per the article, no Underwriter's Laboratory (UL) certification was required
for hospital equipment. Maybe it was felt that it wouldn't be so bad if someone got zapped
in the hospital since there would be a doctor on-hand to resuscitate the zapee. Since
that time medical equipment has been required to undergo stringent safety conformance
requirements that makes electrocution virtually impossible. Now, if we could just keep
doctors from cutting off the wrong limb or removing the wrong organ...
 From the mid 1950s and through mid 1970s,
Popular Electronics magazine ran a series of articles entitled "Solid State"
in order to facilitate the electronics industry's effort to move people from vacuum
tubes to semiconductors. In fact, if Solid State ran every months since its beginning,
this being installment 182 means it began in 1956 - just eight years after the transistor
was invented. Even though the commercial industry had already shifted to almost
exclusively transistorized products, a large part of the consumer base had been
raised on tube radios and televisions. In this case, the news is in regard to Bell
Telephone Labs' recent invention of the
semiconductor charge coupled device (CCD) - the heart of all modern imaging
systems. Prior to the CCD, a vidicon tube, which as the name...
 For as long as I can remember, The Old Farmer's
Almanac (OFA) has included a set of
Mathematical Puzzles in its annual publication. They range in difficulty from
1 (very easy) to 5 (sometimes quite difficult). Having been a faithful buyer and
reader of the OFA for as long as I can remember, I have spent many hours toiling
with some of the more challenging examples. In fact, there were a lot which I never
did figure out and needed to look up the answers in the back (come to think of it,
I experienced the same dilemma with my college engineering textbooks). Because quite
a few of the Mathematical Puzzles are worthy of an engineer's cerebration, contemplation,
and deliberation, they will all be eventually posted here...
 You can see by the news items in this 1962
issue of Electronics World "Recent
Developments in Electronics" column that electronics was make a big transition
in the early 1960s from vacuum tubes to semiconductors. As covered in other magazine
articles of the era, the tiny nuvistor triode tube was a last-ditch effort to keep
vacuum tubes relevant as transistors were making a move into the industry. Computers,
with the increasing availability of semiconductor elements, were beginning to no
longer be the purview of universities, government agencies, and large corporations.
Rather than requiring hundreds of square feet of floor area and massive cooling
systems, newer designs could fit in an office space. Thin film microcircuits took
up a small fraction of the volume needed by traditional printed circuit assemblies
(get a load of the silver Mercury dime used for size comparison). A "high-speed"
serial binary adder had been built using tunnel diode and coaxial delay lines that
blazed along at 125 MHz...
 This article by the Cleveland Institute of Electronics
is a sort of early infomercial in printed form. You probably know that 1960's was a time
of major evolution in electronics with first the transition from vacuum tubes to solid
state devices in the early part of the decade, and then from discrete component circuits
to
integrated circuits in the latter part. Plenty of skeptics swore that the
newfangled fad would quickly fade out due to initially sky-high prices and low
reliability of germanium and silicon devices coming from university and
corporate laboratories. Actually, it was more a matter of hoping it would die
out so that they would not need to re-train and buy new test equipment for their
shops. Others welcomed and embraced the potentials of the new technology and
were determined to get in on the ground floor... |
