|
 Resistance
is the fundamental property of a material to oppose the flow of electric current,
converting electrical energy into heat. From the high-conductivity copper traces
on a PCB to the specialized carbon-film or metal-film resistors that define voltage
levels and bias currents, resistance is the "control valve" of every electronic
circuit. While Ohm's Law provides the basic relationship between voltage, current,
and resistance, physical reality introduces complexities such as temperature coefficients,
power ratings, tolerance variation, and the unavoidable skin effect at high frequencies.
Resistors are not just passive elements; they are precision tools used for limiting
current, dividing voltages...
 The
unijunction transistor (UJT), invented in 1953, was originally
known as a "double-base diode" and explains why to this day the terminals are labeled
"E," "B1,' and B2." It is commonly modeled as a diode connected between two
resistors, with one resistor being variable. As the name implies, unlike a bipolar
junction transistor (BJT) that is more familiar to most people and has two semiconductor
junctions connected to the base, a UJT has just one junction. As is explained in
detail in this 1970 Popular Electronics article, the net effect of the UJT's
arrangement is a region of negative resistance which makes it good for use as an
oscillator. In fact, the relaxation oscillator...
 Proficiency in Morse code is no longer required
as part of obtaining an Amateur Radio license. A proposal to drop the 5 wpm requirement
was first floated by the FCC in 2005. It was actually at the request of the ARRL;
to wit, "In 2004, the League called on the FCC to create a new entry-level license,
reduce the number of actual license classes to three and drop the Morse code testing
requirement for all classes except for Amateur Extra." ARLB018 FCC Proposes Dropping
Morse Code Requirement Entirely Now, there is no code requirement for any license
class, not even the Amateur Extra. A lot of Hams are not happy about it, but times
have changed and the need for code...
 After getting out of the U.S. Air Force
in 1982, I was fortunate to get a job at the Oceanic Division of Westinghouse Electric
Corporation in Annapolis, Maryland. Most of the guys who worked in the area with
me were former electronics technicians from the armed forces. We spent most of our
days (and often evenings) building small quantity specialty systems for the U.S. Navy.
The facility was fairly small and was not set up for high volume production; that
was the purview of the much larger operation based adjacent to the Baltimore / Washington
International Airport (BWI), which built ground-based and airborne radar systems.
Whilst there, I did a lot of
wire-wrap assemblies that went...
 This first installment in a multi-part series
on magnetism appeared in the October 1947 issue of Radio-Craft magazine.
At the time, there was great interest in
magnetic tape and even magnetic wire recorders. Lots of articles
were published on the electronics and mechanics of recorders, but relatively few
discussed the physics of magnetics. Although the title says it is about permanent
magnetic theory, there is also a lot of information on electromagnets. Terms such
as reluctivity, magnetomotive force, magnetic flux, conductivity of electrical and
magnetic circuits, conductance, B-H curves, maxwells, oersteds, and gilberts are
introduced, along with some simple equations...
 Capacitance - the ability of a system to
store an electrical charge - is a cornerstone of electronics, enabling everything
from simple filtering and coupling to complex energy storage and timing circuits.
While the ideal model of two parallel plates is easy to visualize, real-world capacitors
involve a diverse array of materials, geometries, and limitations. Whether dealing
with electrolytic, ceramic, film, or tantalum types, each component introduces specific
characteristics like Equivalent Series Resistance (ESR), dielectric absorption,
and voltage coefficients that can define the success or failure of a design. As
frequencies rise, parasitic inductance and resistive losses often become...
 The dichotomy between the customer who is
worried about the service
shop owner ripping him off and the service shop owner who is worried
about the customer ripping him off is an old one. Given how even normally honest
people allow themselves a "white lie" here and there to consummate a business deal
or pacify the whims of an acquaintance, it is understandable how such suspicions
come to be. In this 1958 issue of Radio & TV News, Mac McGregor and
trusty sidekick Barney Jameson discuss how to handle customers who imply the desire
for or outright request (even demand) special consideration on repair services and/or
replacement parts. The steadfast policy of Mac's...
 This is the
electronics market prediction for Sweden, 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.
Among Sweden's modern-day most recognizable electronics and related manufacturers
are Ericsson, Saab Group and Electrolux, in existence in one form or another since
1965. Automotive company Volvo is also among the largest manufacturers there, although
not specifically of electronics. A number of contemporary resources are available
for obtaining reports (at a cost) on the electronics industry in almost every country
on Earth. Among them are...
 Here is a bit of "outside-the-box" thinking
from the vacuum tube era that is essentially a form of integrated circuit, where
the active and passive components are discrete rather than semiconductor. The concept
was to provide an assembly that could be plugged directly into a signal gain path
tube socket and provide an additional amount of amplification without needing to
do any special wiring or mounting of components to the chassis. The cost of $9.95
in 1951 is the equivalent of $128 in 2026 money, so it wasn't a cheap upgrade
- and that did not include the cost of an additional tube (about another $13 in
today's money). Given typical electronics service shop rates of just a couple
bucks...
 Anatech Electronics offers the industry's
largest portfolio of high-performance standard and customized
RF and microwave filters and filter-related products for military, commercial,
aerospace and defense, and industrial applications up to 40 GHz. Three new
models have been added to the product line in July, including a 30 MHz LC lowpass
filter with 1 dB insertion loss, a 5 MHz LC bandpass filter with a 3-7 MHz
passband, and a 5000 MHz cavity bandpass filter with an insertion loss of just
0.8 dB. Custom RF power filter and directional couplers designs can be designed...
 X-parameters are a frequency-domain behavioral
modeling framework for nonlinear RF and microwave components. They were introduced
commercially by Agilent Technologies, now Keysight Technologies, as an extension
of the earlier Polyharmonic Distortion, or PHD, modeling theory developed by Jan
Verspecht, David Root, and collaborators. X-parameters are often described as the
nonlinear equivalent of S-parameters, but that phrase must be understood carefully:
X-parameters generalize the wave-based, port-oriented language of S-parameters to
large-signal, harmonic-rich, nonlinear operating conditions, but they are not a
universal, exact, global description of every possible...
 Radio-Electronics magazines'
"Service Digest" column regularly reported on issues relevant to the electronics
servicemen who repaired radios, television sets, phonographs, recorders, and similar
items - often in the customers' homes. Then, as now, professionalism and courteous
behavior was often rewarded with word-of-mouth referrals to friends and relatives,
resulting in new business opportunities. An interesting topic also included was
the need to observe extreme caution when working around TV tubes (CRT's) not
just because of the lethally high voltages present, but because of the
danger of tube implosion and the resulting scattering of glass
shards. An example given is that due...
 Prior to the advent of
FET-input multimeters, obtaining a very high input impedance meter
required the use of a vacuum tube circuit that used a buffer stage to isolate the
measured signal from the loading effects of the meter movement. As most people reading
this article already know, the voltage value indicated by a non-buffered meter can
be greatly affected by the meter's loading of the device under test (DUT) if
the meter's impedance is not many times greater than the DUT's impedance.
The voltmeter is used in parallel with the circuit under test, so for example if
the impedance of the DUT is 100 kΩ and the meter's impedance is also 100 kΩ,
the meter will display a value as if the DUT...
 RF Cafe visitor Brad B. just provided
the following
Watkins-Johnson Tech Notes for the collection: v5-3, v5-4, v5-5,
v5-6, v6-2, v6-3, v6-4, v6-5, v6-6, v8-1, v8-4, v9-1, v9-2, v9-3, v9-4, v9-5, v10-2,
v10-5, v10-6. They run the gamut from Solid State Limiting Amplifiers and Antenna
Polarizations to Digital Signal Processing for Multichannel Receiving Systems. Many
old-timers consider the W-J Tech Notes to be some of the best sources of circuit
and systems design guides ever written, especially for military, defense, and aerospace
applications. Waaaaay back in the 1970s and 1980s when I was new to the electronics
design world, offices, cubicles, laboratories, company...
 I'm not sure how much
mechanical filters are used in circuit design these days due to
their somewhat large size and complexity. They typically exhibit a high "Q" with
a relatively flat passband (with some ripple) and very sharp cutoff in the skirts,
and the insertion loss is low compared to lumped element equivalents (for comparative
out-of-band cutoff). Operational frequencies were limited to a few hundred kilohertz,
so they are useful only at intermediate and baseband frequencies. This article,
appeared in a 1953 issue of Radio-Electronics magazine, describes the basics of
mechanical filter design and construction. Mechanical filters from aircraft radio
manufacturer Collins and other can be...
 Temwell is a manufacturer of 5G wireless communications filters
for aerospace, satellite communication, AIoT, 5G networking, IoV, drone, mining
transmission, IoT, medical, military, laboratory, transportation, energy, broadcasting
(CATV), and etc. An RF helical bandpass specialist since 1994, we have posted >5,000
completed spec sheets online for all kinds of RF filters including helical, cavity,
LC, and SMD. Standard highpass, lowpass, bandpass, and bandstop, as well as duplexer/diplexer,
multiplexer. Also RF combiners, splitters, power dividers, attenuators, circulators,
couplers, PA, LNA, and obsolete coil & inductor solutions.
 The most effective method for
isolating DC power traces, low-frequency analog signal traces, high-frequency analog
signal traces, and digital signal traces on a multi-layer printed circuit board
is not simply to "separate everything with gaps." The best-practice method is functional
partitioning combined with continuous, carefully assigned reference planes, controlled
return-current paths, localized power distribution, and layer stackup planning.
In practical PCB design, signals do not travel only in copper traces. Every signal
current has a corresponding return current, and at higher frequencies that return
current follows the path of lowest impedance, usually directly under...
 In this episode of John T. Frye's
"Carl & Jerry" series, the intrepid pair of teenage electronics hobbyists and
Ham radio operators are experimenting with an audio amplifier rig that uses a parabolic
dish for concentrating sound waves at a focal point where they have a microphone
mounted. Aside from picking up bird noises and a neighbor lady scolding her husband
for not properly washing the windows during a round of Spring cleaning, Carl imposes
upon Jerry for a lesson in
feedback techniques - both positive and negative - and the reasons
one is preferred over the other. The story winds up with a clever double entendre
comment referring to osculation...
 We all know that for the most part television
stinks. Back in 1951 when this article appeared in Radio-Electronics magazine,
the technology was very new and it was considered a miracle not to be wasted on
inane programming. Newscasts actually presented news and not opinion, movies and
sitcoms cast the nuclear family, law enforcement, the military, religion, and patriotism
in a positive light rather than as the purveyors of evil in the world. By the end
of the 1960s to early 1970s a lot of that had changed. Political and social agendas
weaseled their way into nearly all programming to the extent that terms like "boob
tube" and even, yes, "smellivision," became common monikers for television...
 "Are we killing the broadcasting goose, layer of many golden eggs?"
Dr. Lee de Forest asked in his inaugural address, upon his election to the presidency
of the Institute of Radio Engineers. So went the opening editorial in a 1930 edition
of Radio News magazine. It was directed at the question of whether excessive,
"gratuitous" advertising was going to be so offensive to listeners that they would
turn off the set and go back to their former silent worlds. Remember that many,
if not most, households, and certainly not automobiles, even had radios at the time.
Building an audience was essential to nurturing the new phenomenon of radio, and
to saturate the listeners with commercials would surely doom...
|
Loading history...
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.
 By 1950, say the author of this story, "No
longer are 'aerials' merely required to transfer electromagnetic energy into
space," in reference to airborne platforms. Following great advancements in radio
and radar technology during World War II, great interest lay in what would
later become referred to as 'stealth' technology and in secure communications. The
transition of aircraft speeds into the realm of supersonic also mandated that projections
beyond the main airframe outline be either eliminated or very much minimized. The
long cable aerials that stretched from the cockpit area to the tip of the vertical
fin, and the round direction finding antennas hanging from below could not be accommodated
at airspeeds above about 300 knots. The aerodynamic drag would be excessive
and the forces would tear the antennas apart. Douglas Aircraft set up one of the
first antenna measurement laboratories...
 The first mathematical rules taught to entry
level electrical and electronics students are those of
Ohm's Law. Georg Simon Ohm was a German mathematician and physicist
who discovered during his experimentations that the current through a conductor
was directly proportional the the voltage potential applied across the conductor.
From there, he deduced the familiar V=I/R relationship that is the foundation to
all of what has followed in the field of electricity. The standard unit of resistance
- the ohm - bears his name. Watt, the standard unit of electrical power, was similarly
named after Scottish engineer James Watt, and the ampere standard unit of current
was named in honor of André-Marie Ampère. The standard unit of electrical potential
- the volt - was named after Italian physicist Alessandro Volta. Sure, most of your
know - or knew - all this...
 Do you think any tool company would publish
an advertisement like this in today's hypersensitive environment? When Weller ran
the ad shown below in the May 1952 issue of Radio & Television News
magazine, nobody anywhere could have conceived of a world six decades later where
the mere sight or mention of a gun would send snowflake types running for the nearest
safe space (which, sadly, has a special symbol
 a la a nuclear fallout
shelter). It is a little surprising that Weller still markets the tool as a soldering
gun rather than, say a heavy-duty, finger-operated, palm-conforming, graspable soldering
implement ;-( Does anyone know whether soldering guns are allowed in
schools these days? Zero Tolerance policies would require...
 There are few better ways to wind down
a work week than with some good old-fashioned (literally)
technology-themed comics. This three fifths of a handful of comics
appeared in a 1944 issue of Radio News magazine. You need to know when looking at
these scenarios that people in the 1940s cherished and revered their radio sets
like people today do with their cellphones. Magical and supernatural attributes
were assigned to them by some, especially the non-technically inclined. Entire families
gathered around the radio in eager anticipation of the latest episode of "The Shadow,"
The Lone Ranger," "Little Orphan Annie," "Jack Benny," and "Inner Sanctum Mystery."
BTW, if you want to experience the aura of old time radio shows, many of them are
available for listening online on the Old Time Radio Catalog website and others...
 Each week, for the sake of all avid cruciverbalists
amongst us, I create a new technology-themed crossword puzzle using only words from
my custom-created lexicon related to engineering, science, mathematics, chemistry,
physics, astronomy, etc. This week's puzzle contains a
special holiday message (clues with asterisks) to all RF Cafe
visitors. You will never find among the words names of politicians, mountain ranges,
exotic foods or plants, movie stars, or anything of the sort. You might, however,
see someone or something in the exclusion list who or that is directly related to
this puzzle's theme, such as Hedy Lamarr or the Bikini Atoll, respectively. Enjoy!...
 Early
masers (microwave amplification
by simulated emission of
radiation), like the lasers (light amplification...),
began life with the requirement of a rare earth-based mineral at its core - in this
case a ruby. Early applications of the maser, as reported in this 1960 Popular Electronics
article, were centered on radars. High amplification and high power was beyond the
capability of common semiconductors like Si, GaAs, or GaN. Required substrate impurities,
gate widths, and thermal control was well beyond the state of the art of the day.
As always, the early pioneers like Dr. Charles H. Townes, inventor of the maser,
accomplished incredible feats with rudimentary tools, including the venerable slide
rule...
 When you hear or read "satellite television," you naturally think of a service like DISH
Network or DIRECTV. When encountered in a 1956 Radio & TV News article, you
know "satellite" must mean "(3) someone or something attendant, subordinate, or
dependent." Such was the case for satellite TV locations in areas where, without
a network of microwave relay towers, communities situated where geography inhibited
standard VHF and UHF broadcast signals from reaching sets with sufficient power
were left with no or frustratingly poor reception. Home-based satellite TV as we
know it today began in the mid 1970s with Pat Robertson's Christian Broadcasting
Network broadcast. Artifacts of that ancient time can still be spotted in rural
areas: 10-foot-diameter dishes with eyeballs, smiley faces, or camouflage patterns
painted...
 An RF Cafe visitor sent this equation to
me a few years ago. It can be found all over the Internet (including here), but
I cannot determine a definite origin. Mathematicians claim that math can explain
everything in the universe, which is not quite true. It can't for example, explain
why my next-door neighbor is a junk hoarder. This
Christmas equation
does not appear to begin with a particular application; it looks like something
from a set of textbook end-of-chapter problems. Even if you don't celebrate Christmas,
it provides a secondary benefit by demonstrating rules for the manipulation of logarithms
and exponents along with basic algebraic rearrangements of terms.
 War Bonds were used by countries, including
the United States, Canada, Germany, and the United Kingdom, to help finance the
expense of war without causing massive inflation caused by printing more money.
Particularly during war times, governments were concerned with any amount of inflation
since it would raise the cost of procuring necessary materials. A meme popularized
(by the government) during World War II was, "Use it up. Wear it out. Make
it do, or do without." Similar to how modern day Savings Bonds work, citizens
bought the bonds at some fraction of the face value (typically 1/2 or 3/4) with
a maturity date of 10, 20, or more years. On or after the maturity date, the bonds
could/can be redeemed for the face value plus and amount of interest which might
have accumulated during the period. I remember while in elementary school in the
early--to-mid 1960s taking a dime to class each week to buy a stamp for a $25 savings
bond. Those bonds matured in the mid 1980s and sat in a box...
 As in the past, I am posting these Radio
Service Data Sheets as a service to someone who might be doing research on
vintage radios and/or restoring one. Roamio is not producing automobile radios anymore,
but they do now make TiVo recorders and streaming media players. The
Crosley Roamio Automotive Superheterodyne Models 95 and 96 was
made in the early 1930s at a time when cars and trucks were just starting to experience
such luxury. Those sets had the power supply and RF receiver components mounted
in the trunk and/or under the seat, with the operator interface controls (tuning
and volume) mounted in the dashboard. Crosley did not begin manufacturing its own
line of cars until 1939, so none of these radios made it into Crosley autos...
 You can add to the long list of technical
wonders promised - and not delivered - to us by the end of the twentieth century
(this is now the 21st century, btw) a
three-dimensional (3D) television set. This 1958 article from
Radio & TV News magazine described efforts already made by the movie industry
for generating 3D films that provided audiences with life-like projections that
were designed to shock their senses by having scary or dangerous objects suddenly
hurled at them. Pictures of a theater filled with people wearing the cardboard-framed
red/blue stereoscopic glasses are a very familiar symbol of the scheme known as
stereoscopy. Another method of 3D image perception was to use horizontal and vertical
polarization along with appropriately configured glasses to separate the images
entering the eyes and relying on the brain to convert a pair of 2-dimensional pictures
into a 3-dimensional image...
 Sound powers for the following equation in
dBA units are referenced to a picowatt (10-12 W). The
threshold of
pain for the human ear is usually taken to be around 120 dBA. One of the
best compilation of noise power level data can be accessed in Chapter 5 of
the OSHA Technical Manual website. Loudness is the subjective human response to
sound. It depends primarily on sound pressure but is also influenced by frequency.
Three different internationally standardized characteristics are used for sound
measurement: weighting networks A, C, and Z (or "zero" weighting). The A and C weighting
networks are the sound level meter's means of responding to some frequencies more
than others...
 Voltage multipliers were found in nearly
every form of battery-powered electronics in the days of vacuum tubes, because of
the 100-volt or more requirement for plate voltages. Primary batteries in 30, 45,
and 67½ volt sizes were produced by Eveready, Burgess, and a few other companies
in order to help simplify biasing circuits. They were bulky and heavy, often comprising
a significant portion of the assembly's volume. Heavy transformers contributed mightily
to the weight and size as well. Exell still manufactures 30, 45, and 67½ V
batteries both for the few products that are still designed to use them, and for
vintage radio owners. Most circuits that need higher DC voltages these days use
DC-DC converters, many of which are ICs...
 This week's puzzle features words and clues,
marked with an asterisk (*), regarding a momentous event which took place this week
on
December 17, 1903. As with my hundreds of previous engineering
and science-themed crossword puzzles, this one contains only clues and terms associated
with engineering, science, physical, astronomy, mathematics, chemistry, etc., which
I have built up over nearly two decades. Many new words and company names have been
added that had not even been created when I started in the year 2002. 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...
 Most of us have heard of the National Association
of Broadcasters (NAB). Founded in 1922 at the dawn of commercial radio broadcasting,
it is still in existence today. When commercial television broadcasting "stepped
out" in a major way in the early 1940s, industry chieftains and station owners decided
that their new media paradigm was unique enough to warrant a separate union, so
the
Television Broadcasters Association (TBA) was formed. A lot of
effort went into establishing and building a coalition with enough influence in
the marketplace and with government regulators, independent of radio, to exist as
a force to be dealt with. Many people believed that radio as an entertainment and
news media source would decrease at a rate as great or greater than television was
increasing. Once again, experts were not successful at predicting behavior of the
citizenry, which was true both in the United States and around the world... |
An RF Cafe visitor sent this equation to
me a few years ago. It can be found all over the Internet (including here), but
I cannot determine a definite origin. Mathematicians claim that math can explain
everything in the universe, which is not quite true. It can't for example, explain
why my next-door neighbor is a junk hoarder. This
Christmas equation
does not appear to begin with a particular application; it looks like something
from a set of textbook end-of-chapter problems. Even if you don't celebrate Christmas,
it provides a secondary benefit by demonstrating rules for the manipulation of logarithms
and exponents along with basic algebraic rearrangements of terms.
