|
 Time to put on the thinking cap again for
three more "What's
Your EQ?" circuit challenges, compliments of Radio-Electronics magazine
in May 1962. The first is a classic "black box" type problem which, from reading
its description, involves some sort of resonant circuit. that's all I'll say on
that. The next, called "An Easy One?" should, by the way it is drawn, be a clue
that it might be easier to solve if you re-draw it to make a familiar-looking circuit.
Hint: Summons the spirit of Sir Charles Wheatstone. Just the name of the last one,
"Iterative Network," is enough to induce a cold sweat. As with most of these "What's
Your EQ?" problems, successful completion of a first year college circuits course
is plenty to get through them. A few are better attempted by people with hands-on
experience troubleshooting circuits, but don't let that scare you off...
 KR Electronics has been designing and manufacturing custom filters
for military and commercial radio, radar, medical, and communications since 1973.
KR Electronics' line of filters includes lowpass, highpass, bandpass, bandstop,
equalizer, duplexer, diplexer, and individually synthesized filters for special
applications - both commercial and military. State-of-the-art computer synthesis,
analysis, and test methods are used to meet the most challenging specifications.
All common connector types and package form factors are available. Update: KR Electronics
has been acquired by NIC, where KR Electronics'
legacy of quality and innovation will continue to thrive, offering the same trusted
products and services under NIC's leadership. For over three decades, NIC has delivered
high-quality component performance and reliability, ensuring the successful deployment
and operation of our clients' mission-critical solutions. Designed and manufactured
in the USA. Please visit NIC today to see how
we might be of assistance.
 Roger McCraw sent me these photos from his
assignement in U-Tapao, Thailand, cicra 1973. I submitted a couple of the images
to AI for colorization - amazing! Says Roger, "The pictures were taken at U-Tapao,
Thailand and are dated April 1973. I was there from Jan 73 till Jan 74
and was a 30351 in the 1985th Comm Squadron. Since I was the newbie I was selected
to change the light bulbs so I decided to give a Nixon peace sign for the photographer.
The MPN was on a turntable so it could service both approaches to the runway. The
ATC displays were in a trailer that was attached to a building, it was just to right
of truck in picture. I only remember the name of one person because his name is
listed on TWS website. He bought a four function calculator...
 This installment of the After Class series
in the December 1957 edition of Popular Electronics deals with inductors.
It is a beginner-level introduction to how
reactive components behave in circuits. For some reason the concept
of magnetism's influence on electrical current (present with inductors but not
capacitors) seems to be more difficult to comprehend than that of electrons, even
though James Clerk Maxwell shows in the mid 1800s that the two phenomena are interrelated.
I am tempted to say that back in the 1950s when this article appeared, people were
less familiar with the relatively new concept of electronics, but in thinking about
it, your typical 2019 reader is probably even less likely to know anything at all
about electronics or the way basic components work. I would bet that maybe 1% could
even tell you the difference between AC and DC current...
 Not very long ago I mentioned
Jean Shepherd (original assignee of W9QWN and later K2ORS call
signs) as being one of my favorite old-time radio broadcasters (1960s-1970s). Jean
was famous for recounting stories of his own life and for reporting news of the
time in a way that could hold you in rapt attention from beginning to end. His humor,
wit, and command of the English language was acknowledged by his contemporaries.
If you listen to enough of his broadcasts you will notice the frequent mention of
electronics and his experiences as a licensed amateur radio operator beginning at
a tender young age. Just recently I listened to him recount his first day in high
school when a SNAFU in the computer-generated (must have been a UNIVAC) class schedule
mistakenly had him reporting to the girls' swimming pool...
 I was born in the era of screw-in glass
fuses in household electric service panels. There was always a supply of replacements
in the cabinet above the stove. Sometime around 1978, prior to enlisting in the
USAF, I replaced the fuse panel with a Square D circuit breaker panel - a skill
learned through four years of electrical work. In the Air Force, I worked on a 1950s
era air traffic control radar system which consisted of many chassis assemblies
having fuse holders on their front panels. The racks themselves had a circuit breaker
panel, but it was a retrofit from sometime in the early 1970s. That was my introduction
into the wide variety of cylindrical glass fuses - high and low voltage, normal-,
slow- and fast-blow, time delay, etc. I learned of the reason why circuit designers
employed each type, and always used exact replacements when possible. Later, as
a circuit and systems design engineer myself, I always was careful to specify the
most
appropriate fuse type. This 1960 article in Radio-Electronics magazine
is a good primer on fuse handling...
 Being that this
Circuit Quiz appeared in a 1966 issue of Radio-Electronics magazine,
the amplifier components shown are transistors, rather than vacuum tubes. I have
to admit to not doing very well on it. One of the challenges is first determining
what the intended function of the circuit is supposed to be, then you figure out
what is wrong with it. Spoiler alert: I'm going to use circuit A as an example.
It is declared to be a voltage regulator circuit, and the deficiency is the lack
of a stable voltage reference. The architecture is typical of a voltage regulator
with the common base setup used to increase the current supply. However, there is
no reason to necessarily assume the DC IN is not itself already regulated, and the
function if merely to increase the current supply capacity. If that is the case,
then the circuit seems sufficient as shown. Maybe the fact that there is no problem
otherwise should tell you make an assumption about the designer's intention and
look for something that would be suspect under that condition. Anyway, that's my
excuse and I'm sticking with it ;-)
 This rather extensive article from a 1947
issue of QST magazine describes the method used by author Philip Erhorn
to experimentally determine optimum
spacing for the parasitic elements of his antenna. Unless you
have electromagnetic field simulation software available for designing antennas,
the procedure typically involves beginning with published formulas for element length
and spacing, then resorting to a cut-and-test method of finding a combination that
works best for your installation and goals. Almost certainly no two Hams end up
with identical configurations because differences in terrain...
 Since this is a presidential election year,
I figured it would be a good time to post a tongue-in-cheek- story that appeared
in the November 1952 issue of QST magazine about a fictional American president
J. Willoughby Winkelspoof. The American Radio Relay League
(ARRL) always has been and still is apolitical, so don't take seriously anything
you read here. If you are an astute follower of politics, you might pick up on the
nuances woven into the story, and might even marvel on how much the political landscape
has changed in the half century since Pres. Winkelspoof graced the Oval Office...
 This is Part II of a 3-part series of articles
on
magnetostriction devices. At audio and low IF frequencies, the
use of ferrite elements to construct relatively high-Q resonant circuits for filtering
was a big deal in the middle of the last century. Although not presented in this
article, design formulas and tables were published to implement the familiar Butterworth,
constant-k, Chebyshev, Gaussian, and other types. Tuning, particularly for higher
order filters, could be a chore since it involved a cut--and-try method on the ferrite
rods. However, that is what was available in the day, and it evidently worked well
enough to be worth the trouble for desired...
 Electronics World magazine often published
electronics-themed crossword puzzles. Unlike RF Cafe engineering crosswords
I created for two decades that use only technical words and clues, this one does
include some unrelated words. A couple clues I was surprised to see pertain to radar;
e.g., 32A: Small visible mark on a radar or scope screen, and 44A: Identification
Friend or Foe. Some words require a familiarity with technology of the era, but
you shouldn't have much trouble. You'll need to print this out on paper to work
it..
 Advances in
transformer technology are driven by the need for miniaturization and efficiency,
particularly in airborne and high-frequency military equipment. By optimizing core
materials and fabrication, engineers can significantly reduce the weight and physical
dimensions of transformers. A major technical milestone highlighted in this 1964
Electronics World magazine article, was the development of grain-oriented
silicon steel, which, through precise crystal alignment, offers superior magnetic
properties and reduced energy losses compared to traditional soft iron. Modern design
further mitigates power loss from hysteresis and eddy currents by employing thin,
insulated laminations...
 It didn't take much in the early days of
radio to capture the curiosity of consumers with buzz phrases like a "Mystic Hand"
to keep the radio tuned properly - really just AFC control, and a "Phantom Conductor"
circuit that boosted the volume of high level audio (a nonlinear amplifier). Here
are 4 more Radio Service Data Sheets from Radio-Craft magazine.
Crosley Model 1316 Radio Service Data Sheet,
Westinghouse Model WR 207 & WR 208 5-Tube Dual-Band Superheterodyne
Radio Service Data Sheet,
RCA Victor "High-Fidelity Electrola," Model R-99 Radio Service
Data Sheet...
 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)...
|
 • Skyworks
Reports Nearly $1B in Q2 Revenue
• Price
Rises for Analog, Discrete and Passive Devices
• Apple-Intel Foundry Could
Reshape U.S. Chip Manufacturing
• China Loses Monopoly over
Rarest of Rare Earths
• Samsung
Memory Chip Worker Union Strike Averted
 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.
 OK, class, put your books away and take out
a pencil. Spread your chairs out because we're going to have a short test today.
A collective sigh permeates the room. Remember those days? I still have nightmares
over those moments, and they were decades ago for me. At least this "Electronic
Noise Quiz" from the August 1962 edition of Popular Electronics
won't affect your GPA. Sometimes PE's quiz illustrations are kind of hard to
interpret, but this one does a pretty good job (except item 'E', but I'm not
telling what it is since nobody helped me). You will need a fairly diverse
background in consumer type electronics to do well, and having a few gray hairs
will probably help as well. Good luck. BTW, my score was a somewhat embarrassing
80%...
 This "Recent Developments in Electronics"
from a 1960 issue of Electronics World had a lot of
antenna news that included a retarded surface wave antenna with high gain and
low silhouette for use in airborne early warning radar as well as ground based and
shipboard radar, a pair of 60-foot tropospheric scatter antennas that are specially
mounted at opposite ends of a 180-mile long section of the Gulf of Mexico, and a
104-foot-long rotating 50-ton radar antenna used for the SAGE early warning system.
Also reported was Westinghouse Electric's airborne Stratovision for broadcasting
educational television programming to rural areas out of reach of existing
towers...
 The 1950s was a time when futurists were predicting
that
domestic robots would be common place items in households. By the turn of
the century, mankind, freed from the drudgery of manual labor, would have plenty
of time for recreating, resting, and sitting around brainstorming the next big
thing. Here it is 12 years into the new century and at the most, a fraction of a
percent of the population even has a Vroom robotic floor vacuum - and it looks
nothing like a human. This comic from the November 1957 Popular Electronics
exemplifies the visions of the last century. Now, maybe by the end of the 21st
century we'll finally be there...
 Sometime around 1980, while stationed at
Robins AFB, Georgia, I finally succumbed to the peer pressure of other more sophisticated
audiophiles in the barracks and bought a "real" stereo. Unlike my roommate who had
a full compliment of rack-mounted gear, my meager enlisted military pay only allowed
for a mid-grade instrument. The solution was a
Sansui TA-300 Integrated Tuner Amplifier. It put out a whopping 30 watts per
channel, but unlike my existing radio (a Readers Digest 800-XR), those 30 watts
were nearly distortion free when driving good speakers. Having only the pathetic
5 W speakers that came with the 800-XR, I designed a set of speakers rated for
60 W, and built the enclosures myself in the base woodshop. Unfortunately, in
preparation for a household move about 20 years ago, I sold the Sansui and the
speakers...
 This is a nice short article covering the
calculation of inductances for coils wound on cores and wire sizes. It appeared
in a 1932 issue of Short Wave Craft, but of course inductance has not changed
since then so it is still relevant. The author recognized that standard formulas,
although concise and accurate, are sometimes difficult to work with when calculations
for a large number of values is needed for a particular circuit design. To address
the situation, he presents a handy nomograph, chart, and a table of typical values.
He also introduces a rarely seen term "Nagaoka's correction factor*" for skin
effect. A smartphone app, a spreadsheet, or a desktop computer program would be
used today to calculate inductance...
 Since 2000, I have been creating custom
engineering- and science-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 or a geographical location
like Tunguska, Russia, for reasons which, if you don't already know, might
surprise you...
 Lots of
RF transmission cable parameter charts are available on the Internet, but what
sets this one apart is that is has entries for some of the popular 300 Ω
twin-lead cables of the rooftop television antenna era. It appeared in a 1956 issue
of Radio & Television News magazine. Mentioned in the article is the
reason most TV lead-in cable was colored brown was to help keep the sun's ultraviolet
rays from penetrating and deteriorating the plastic. Author Robert Gary claims silver
coloring was also used to reflect the UV, but I don't recall ever seeing silver
twin-lead - maybe it was a regional thing like for in the southwest. At the time,
μμfd (micro-microfarad) was commonly used rather than pF (picofarad). He also mentions
the G-Line transmission cable used by many of the...
 Exploiting the electronic nature of living
organisms through contrived application and manipulation of electric currents has
been a goal of researchers (and quacks) ever since Luigi Galvani first discovered
that connecting a battery lead to a frog's leg would cause it to kick.
Psychogavanic reflex (PGR) is the technical term for the science. Once it
was determined that all forms of fauna would respond to electrical stimulation,
it wasn't long before the same sort of treatment was applied to all forms of
flora. Many people (not me, for the record*) believe that talking to plants can
influence their health and growth, so why not - so goes the reasoning - try
electric currents as well. We all know from spy, war, sci-fi, and horror movies
that under the right conditions...
 This is yet another example of humorous
- and clever - poetry written by Hams from back in the 1940s... November 1942,
to be exact. It, along with "''Somewhere in Australia," appeared in the ARRL
magazine QST. As alluded to in the title, "Ravin," it is a play on
Edgar Allen Poe's famous "The Raven" poem. A editorial note added, "QST's mail
these days is laden with [aspiring poets'] efforts. Of these, many are, of
course, quite devoid of merit; others, while readable, are unavailable simply
because of space limitations. Yet so strong a flood of contributions must
indicate at least a partially equivalent strength of reader interest...
 A few months ago, one of America's big-city
mayors made the proclamation, "We're not going to make America great again. It was
never that great." There has been a big push in the last decade to not only erase
the
significant accomplishments and sacrifices of America's and Western Europe's
past, but to vilify those people and institutions that make up that past.
Purging the records and rewriting history is a tried and true method of assuring
few have easy access to archival material documenting the accomplishments of the
nation's past. Along with desiring to provide useful and interesting material to
people seeking technical and historical information, my motivation...
 This
subscription renewal for Radio-Electronics magazine was tucked
inside one of the group of 1969 issues I bought on eBay. It's not a big deal,
but is always interesting to see how the companies communicated with customers
in the day. Note that the mailing address for Radio-Electronics is simply
Boulder, Colorado, with no street address given - all the mailmen must have
known where they were. The cost was $12 per year...
 This line from the Basic Navy Training
Courses is very important when considering electrical machines: Many electrical
devices and machines operate on the principle of "transformer
action." They in fact are not transformers - but the theory of their operation
is best explained by considering them as if they were transformers. It is part of
chapter 21, entitled, "Some Electrical Machines - Transformer Action," which provides
a simple introduction to induction motors and generators, regulators, frequency
converters, and synchros. If you are a newcomer to the field of electricity
and/or electronics, or if you just want to brush up on old knowledge to be
conversant at office parties, this is a great short read. A quiz is provided at
the end...
 After many years of reading
Mac's Service Shop sagas, a persistent theme seems to be Barney's refusing
to refer to equipment schematics while troubleshooting, thereby often wasting
valuable time. According to business owner and electronics sage Mac McGregor,
assuming that what is typical for most sets will apply to all sets can and does
create a fertile environment for frustration - and profit loss. Mac's advice to
check "simple things first," has always been my troubleshooting philosophy -
maybe because identifying the "hard things" has nearly been my undoing many
times when the trouble is not simple. One of first things I do is check
switches, connectors, and user-accessible potentiometers for proper operation
(when potentially responsible for the problem, of course). I've written many
times about how often a dirty connector is the culprit...
 This week's crossword puzzle will keep you
busy for a while. Since 2000, I have been creating
custom engineering- and science-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...
 Here are a few
tech-themed comics from the April 1967 edition of Popular Electronics
magazine depicting the perception of techies during the era. As mentioned
before, stereo equipment was a big deal in the era, back before most people
listened to music through ear buds attached to smartphones. When in the USAF in
the early 1980s, a sure sign of hipness was to have 19" equipment rack in your
barracks room, stuffed full with a reel-to-reel tape deck, a high end AM/FM
receiver ("tuner," to the audiophile), power amplifier that could deliver at
least 200 W per channel, a dual cassette deck, turntable (referring to it as a
"phonograph" revealed your squareness). Of course no self-respecting stereo
aficionado would be caught dead with an 8-track tape deck in the rack... |
