|
 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...
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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.
 Billed at the time as the longest
microwave relay system in the world, this report on Bell Telephone Systems'
transcontinental installation came just a month after being put into commercial
service. At a cost of $40 million ($512 million in 2026 dollars per BLS Inflation
Calculator) when this article was published in Radio & Television News
magazine, the system relays telephone calls and radio and video program material
along a chain of 107 microwave towers, spaced approximately 30 miles apart. It was
a big deal to be able to watch a TV show from New York City in Los Angeles, and
vice versa; we take worldwide broadcasts for granted nowadays...
 If you are familiar with aircraft electronic
navigation systems, reading in this 1951 Radio-Electronics article's opening
paragraph about how "Omnirange
aircraft navigation will make air travel safe, dependable, and predictable regardless
of visibility, and volume of air traffic," really makes you realize how far we have
come in the last seven decades. The network VOR (VHF Omnidirectional Range) station
revolutionized aviation by enabling precision navigation using relatively simple,
reliable, and inexpensive equipment in the cockpit which enables pilots to fly from
waypoint to waypoint across the country. Eventually, five variations of VOR evolved
with...
 National Union Radio Corporation was ahead
of its time in terms of hiring women engineers. Admittedly, they and all other manufacturers
were dealing with a shortage of male engineers due to the ongoing need by the military
for fending off the scourges of fascism, Nazism, communism, socialism, and all the
other "isms" of the day that threatened to overtake the world. However, they should
receive due credit for going out of the way to promote the sciences as careers for
the fairer gender. The advertised positions required the successful applicant to
have earned a bona fide degree in physics, electrical engineering, chemical engineering,
mechanical engineering...
National Union Radio Corporation was ahead
of its time in terms of hiring women engineers. Admittedly, they and all other manufacturers
were dealing with a shortage of male engineers due to the ongoing need by the military
for fending off the scourges of fascism, Nazism, communism, socialism, and all the
other "isms" of the day that threatened to overtake the world. However, they should
receive due credit for going out of the way to promote the sciences as careers for
the fairer gender. The advertised positions required the successful applicant to
have earned a bona fide degree in physics, electrical engineering, chemical engineering,
mechanical engineering...
 Samuel Milbourne, of Greenwood, Mississippi,
was a regular contributing author for Radio News magazine. His title was "Expert
Serviceman" and his columns' themes were - you guessed it - servicing electronics
products like radios, phonographs, tape recorders, and even some televisions. Being
the February 1942 issue, the United Stated had just been drawing into World War II
with the bombing of Pearl Harbor by Japan's naval air force. Prior to the attack,
which quickly made headlines across the nation and across the world, many people
did not know much about happenings "over there" in Europe and the South Pacific.
Most people were too busy minding their own...
 You will not find the name Central Intelligence
Agency (CIA) mentioned anywhere in this WWII era (1945 Radio News magazine) story
reporting on the activities of the
Foreign Broadcast Intelligence Service (FBIS), since the CIA was not formally
established until 1947. FBIS became a branch of branch the CIA, however. Per
the CIA website "For nearly 70 years, the Foreign Broadcast Information Service
(FBIS) monitored the world's airwaves and other news outlets, transcribing and translating
selected contents into English and in the process creating a multi-million page
historical archive of the global news media." Equally surprising is that the British
Broadcasting...
 Having never owned a diesel-powered car or
truck, I can't say whether not having a high tension (voltage) ignition system eliminates
any possible interference with AM radio reception. Although not many people listen
to
AM radio these days, there was a time when it was still a popular option along
with FM, and a time before that when it was the only option. Diesels have long been
much more prevalent in Europe, so those of you who were around in the era might
recall whether you were contently listening to the BBC in static-free bliss while
your petrol-powered friends were fighting the ignition noise battle with chokes,
capacitors, and resistor wires. Ignition...
 Grid dip meters, aka grid dip oscillators
(GDO in this 1956 Popular Electronics magazine article), are extremely useful for
determining when a circuit is functioning at resonance. In the words of Sherlock
Holmes, "It is simplicity in itself" the way a GDO operates. The grid dip oscillator
emits power at a calibrated frequency which is absorbed (or not) to a degree depending
on how close to resonance the external circuit under test is to that frequency.
The nice thing about this type of instrument is that it does not need a wired or
other type of physical connection to the circuit. Of course modern day GDOs do not
use vacuum tubes with grids that...
 Although this "Algebra
in Electronic Design" article in the February 1952 issue of Radio-Electronics
magazine does not claim to be the second part of author Edmund Berkeley's "Light
Sensitive Electronic Beast" article from the previous December's issue, it does
help to know that the "Squee" mentioned here came from there. Squee is a Robot Squirrel
which has four sensing organs, three acting organs, and a small electronic and relay
brain. "Although Squee is not a very clever robot, he does have a small amount of
memory and of reasoning ability." Boolean logic (aka Boolean algrbra), a common
part of modern electronic circuits and systems, was a relatively new...
 At least for now, I am going to only scan
and post schematics & parts lists like this one featuring the
Garod model 5A1 "Ensign" tabletop radio in graphical format. It appeared in
the September 1947 issue of Radio News magazine. There are still many people
who restore and service these vintage radios, and often it can be difficult or impossible
to find schematics and/or tuning information. I will keep a running list of all
data sheets to facilitate a search...
 For a long time, I have been scanning and
posting Radio Service Data Sheets like this one featuring the
Emerson Model AZ-196 (Chassis AZ) tabletop radio. It appeared in the August
1938 issue of Radio-Craft magazine. There are still many people who restore and
service these vintage radios, and often it can be difficult or impossible to
find schematics and/or tuning information. Back in the day, both service shops
and do-it-yourselfers relied on these documents for making repairs and tweaking
the performance since manufacturers would not make the information available to
anyone other than an authorized dealer. A nicely restored example of the Emerson
Model...
 Sylvania Electric Products was born out of
Hygrade Sylvania Corporation in 1942, and continued until 1959 when it merged with
General Telephone to form General Telephone and Electronics (GTE). That puts this
1951 promotion in Radio-Electronics magazine smack dab in the middle of
their existence. Sylvania, like most major electronics products companies of the
era, made vacuum tubes, CRTs, incandescent lamps, radios, even proximity fuses
for warheads during World War II. In the 1960s and 70s, Sylvania produced
semiconductor components and computers. Brick-and-mortar stores, whose primary
competitors were mail-order businesses back then, were...
 In the 1930s, electricity and electronics
were mysteries to most of the population. The concepts were relatively new and few
had a firm grasp on the technology. That reality was exploited by Hugo Gernsback
during the
1934 Electrical Exposition to challenge attendees to discover how the radio
receiver sitting on the top of an empty, clear glass case was being powered. It
was a clever ruse that reportedly stumped most people. The secret is revealed here
in this 1934 issue of his Radio-Craft magazine. BTW, my guess is that an
even smaller proportion of our current citizens would be able to figure it out,
or for that matter even realize that maybe there should be a power source of...
 Here is a perfect example of setting up a
"straw man" in order to knock it down. Per Merriam Webster, a "straw man" is, "A
weak or imaginary argument or opponent that is set up to be easily defeated." The
advertising team didn't even do a very good job of it since nowhere in the copy
is there a reference to why the
Indian Rope Trick in particular is alluded to regarding Mallory capacitors.
It mentions a "trick," but that's all. Ah, I just figured it out - they hanged themselves
professionally with the rope! BTW, type "FP" supposedly stands for "Formed Plate,"
a special method Mallory used to increase the surface area of metal layers to get
higher capacitance...
 Gaining a design
engineering position with
Google is (or at least was) notoriously difficult because of some of the tests that
are administered - depending on the hoped-for job. Skills in logic, creativity,
problem solving, and fundamental mathematics and science are among the capabilities
that must be demonstrated. IBM was known to have tough entry requirements for customer
field service representatives back in the early days of computers - for technicians
as well as for engineers. "A man who can think his way through a problem can learn
electronics, but a person lacking in analytic abilities will never be a good service
engineer," said an employment...
 As is frequently the case, John T. Frye's
intrepid teenage technophile experimenters,
Carl Anderson and Jerry Bishop, find themselves in an unplanned adventure. Often
times they end up applying their electronics knowledge to bail themselves out of
trouble, but this time the pair - and a friend - ended up helping the police catch
some bad guys (an oft-occurring theme). As you will see after reading "All's Fair
--," the device used would some day (today) be used by automobile manufacturers,
at the behest of law enforcement agencies, to enable remote control of somebody
else's vehicle. This technodrama appeared in the September 1963 issue of Popular... |
Billed at the time as the longest
microwave relay system in the world, this report on Bell Telephone Systems'
transcontinental installation came just a month after being put into commercial
service. At a cost of $40 million ($512 million in 2026 dollars per BLS Inflation
Calculator) when this article was published in Radio & Television News
magazine, the system relays telephone calls and radio and video program material
along a chain of 107 microwave towers, spaced approximately 30 miles apart. It was
a big deal to be able to watch a TV show from New York City in Los Angeles, and
vice versa; we take worldwide broadcasts for granted nowadays...
