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 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)...
 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...
|
 • Apple-Intel Foundry Could
Reshape U.S. Chip Manufacturing
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Rarest of Rare Earths
• Samsung
Memory Chip Worker Union Strike Averted
• AI
Glasses Shipments Grow 322% in 2025
• ChatGPT
Solves Elusive Geometry Proof
 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.
 How is this for a prescient prediction from
the early 1960s? "As a result of modular and integrated circuitry techniques, all
future circuit design work, regardless of degree, will become the responsibility
of the component manufacturer instead of the equipment producer." Texas Instruments'
(TI)
Jack Kilby is credited with designing the first integrated circuit
in 1958. The first commercial IC, Ti's
Type 502
flip-flop, had just hit the market in early 1960, and already pundits were prognosticating
and ruing the disappearance of circuit designers. Maybe it was concerns over job
security that they seem to favor forever building every circuit from discrete transistors,
resistors, capacitors, and inductors. Rumor has it they also lobbied for the perpetual
existence of the buggy whip and horse-drawn farrow industries...
 Electric induction heating has been used in
manufacturing processes since shortly after Benjamin Franklin invented electricity.
Of course I jest about Franklin; he didn't invent electricity but discovered that
lightning was a form of electrical discharge. One of the most energy-consuming forms
of induction heating is that used by Alcoa for smelting aluminum. Beyond that are
many thousands of processes ranging from forming, tempering, and joining metal parts
to cooking food and curing adhesives. Both Tocco and Ajax-Northrup, now Ajax Tocco,
brands of equipment are featured in this 1955 article which appeared in Popular
Electronics magazine. Some processes work by directly inducing a high current
in the primary target object - usually metallic - being treated...
 Did you know that the Hallicrafters line
of radios is
named after founder Bill Halligan (W9WZE)? Hallicrafters, founded
in 1932, was a major manufacturer of amateur radio gear. During the years of WWII
they ruggedized some of their products to survive the harsh environments of battle.
Hallicrafters was sold to Northrop Corporation in 1966, at which time the product
line essentially ceased. Their gear is still very collectible by aficionados of
vintage Ham equipment. This story from the February 1943 QST provided an
inside look at the production floor at Hallicrafters. Having cut my figurative electronics
teeth on radar and radio equipment built with tubes and point-to-point wiring while
in the USAF, and then later as an assembly/test technician at Westinghouse Electric
building sonar equipment...
 Finding information on the
Osgood Lens, invented by James R. Cravath, is challenging.
For as prominent as it was in magazines like The Saturday Evening Post
in the late 1910s and 1920s, there is not even a Wikipedia entry for the lens type
or the man according to my searches. Although not exactly the same as the Fresnel
lenses used by lighthouses since the 18th century, the concept is basically the
same. Of course the Osgood company was careful not to use the term Fresnel in their
literature for potential patent infringement reasons. Some vehicles might have been
fitted with them as a factory installed option, but they were also sold as add-on
items. According to the literature the tiered stack of prism-shaped glass directed
the headlight beam toward the road...
 For some reason the
subject of grounding has been very prominent in my reading in
the last few days. The chapter I just finished reading in one of David Herres' books
on the National Electric Code (NEC) covering grounding of commercial and
residential services, an article by H. Ward Silver in QST titled,
"Grounding and Bonding Systems," and now this article by John T. Frye (of
Carl and Jerry fame) on grounding, makes for a wealth of knowledge. Mr.
Frye takes a unique approach at teaching by exploiting his gift for story-telling.
In this article, electronics repair shop owner Mac gives technician Barney a nice
bit of tutelage on what constitutes a good Earth ground and what does not. In some
environments, treating the soil with an electrically conductive substance is necessary
to establish a suitable ground without having to drive...
 Here is a short tutorial on
resistor-capacitor (R-C) combinations and the time constants created
by their combinations. It's pretty basic stuff, but there are new people coming
into the field of electronics all the time so it is worth posting. Discussed are
coupling circuits, filter networks, differentiators, and time-delay circuits. The
"After Class" feature is a series run by Popular Electronics magazine in
the 1950s and 1960s. As with this installment, "After Class" presented topics on
electricity and magnetism that served not just as new material for beginners, but
was a good review even for seasoned practitioners of the craft...
 As legend goes, the use of microwaves for
preparing food was pursued after a serendipitous discovery by Raytheon engineer
Percy Spencer whereby he noticed the chocolate bar in his pocket had melted while
he was working near a radar transmitter magnetron. Being a newly discovered phenomenon
in 1945, Mr. Spencer was probably not aware that his own body parts were being likewise
cooked, but he did recognize the commercial potential of an oven that used microwaves
to cook food. It only took Raytheon (Amana) to have the first
Radarange available for sale to professional kitchens. This article
was printed a full decade after the discovery and even then the size and power consumption
was too great for grandma's countertop...
 Television, in 1955, was still a relatively
new phenomenon to many - maybe even most - people. According to multiple sources,
the portion of American households with a TV set went from under 20% in 1950 to
nearly 90% ten years later in 1960. That was a meteoric rise, particularly considering
the expense of even a minimal TV. The technology was not even available commercially
when most people were born, so the rush to join in on the craze was akin to the
mass adoption of cellphones in the 1990s. "Carl & Jerry" creator John Frye used
his pair of electronics-savvy teenagers to help make the "magic" behind recreating
a moving picture on a
cathode ray tube (CRT) miles away from where it was created. Water
flowing through a garden hose has often been employed as an analogy for current...
 The
Beverage Antenna, very familiar to amateur radio operators, is
a simple but efficient, highly directional, non-resonant antenna that consists of
a single straight wire of one or more wavelengths that is suspended above the ground.
It is orientated parallel to the direction of intended reception. One end is terminated
to ground through a resistor, and the other is connected to the receiver. The following
quote comes from the patent (US1,81,089) text: "In accordance with theoretical considerations,
if an antenna were to be freely suspended and if the surface of the earth constituted
a perfectly conducting parallel plane, current waves would travel through the antenna
conductor at a velocity equal to the velocity of light...
 It's funny how often topics crop up bemoaning
the current state of society, technology, etc., as if they are suddenly new plagues
upon the entities concerned. That's not to say the subjects are not worthy of being
brought to the forefront of public awareness, but often times in fact those same
issues are exactly the same or reincarnations of former "emergencies" in need of
immediate attention. I have posted numerous articles and editorials from vintage
electronics and hobby magazines lamenting the
poor state of youth involvement, with blame being laid in the
lap of some newfangled hobby or activity that is presently stealing away erstwhile
brethren. The effort is usually not in vain since the intended effect of motivating
fellow enthusiasts to reinvigorate and motivate those drifting prodigals...
 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 or a geographical
location like Tunguska, Russia, for reasons which, if you don't already know, might
surprise you...
 If you happen to be Estonian, you might think
of something entirely different than most of us do when we hear the word "getter." In fact, you probably capitalize the word since it is
the name of a pop singer from your country, Getter Jaani. If you are a child living
in Japan, you would probably think of Getter Robo, an anime from a popular cartoon
series. I, and I dare say just about everyone else that visits RF Cafe, knows getter
as that silvery deposit (typically barium) that resides inside vacuum tubes for
the purpose of helping to maintain the vacuum and to absorb pesky random molecules
that might otherwise cause electrical noise in the circuit. This article from a
1958 edition of Radio-Electronics discusses the purpose of getter. BTW,
I had never heard of either of the other two Getters due to OGS (old guy syndrome)...
 Chapter 16 of the "Electricity - Basic Navy
Training Courses" introduces concepts of
alternating current (AC) motors, their electric supply, and controls.
It is part of the NAVPERS (Navy Personnel) 10622 series which is highly regarded
both in and out of the military. The manuals were first written in the middle of
the last century and have been upgraded a few times since then, but if you compare
the sections this one on AC motors in both the original and most modern versions,
not much - if anything - has changed. If you have an interest in motors and want
to understand the basics of how they work both as motors and generators (AC and
DC), then there is not a much better source from which to start...
 Air Route Traffic Control Centers, now using
the acronym ARTCC rather than ARTC as used in this 1960 article, were and still
are the human and computer command and control facilities responsible for safe and
orderly flow of air traffic in the U.S., and a worldwide network of Area Control
Center (ACC) handles everything else in a massive coordinated effort. The advent
of radar during World War II and the ensuing evolution of it and electronic
computers in the following years struggled to keep pace with the equally rapidly
evolving aircraft design and capability. A simple control tower with air traffic
controllers using binoculars and a radio mike could not handle the volume of airplanes
and helicopters traversing the skies and patronizing busy terminals. Many forms
of electronic navigation aids were developed including very high frequency omnidirectional
range (VOR), direction finders (DF) using antenna nulling for finding radials to/from
FM radio transmitter, long range navigation (LORAN)...
 Studies of motors usually begin with the
direct current (DC) type - maybe because most students have already
had hands-on experiences with motors in models (cars, boats, airplanes) and/or electricity
experimenter kits. They are small, cheap, and a simple flashlight battery (the ultimate
in safety) makes them run. An alternating current (AC) motor requires either a direct
connection to the house current or use of a step-down transformer, which still carries
with it a high risk factor. This chapter of the U.S. military's Basic Navy Training
Course (NAVPERS 10622) conforms to the tradition, and follows in the next chapter
with AC motors and generators. While reading through the text, I ran across the
unfamiliar term "kickpipe" and wondered... |
