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 In the days before people were so easily
offended by light-hearted poking, it was not uncommon to find magazine articles
written by the wives of hobbyist husbands lamenting the habits and proclivities
of their matrimonial mates. Over the years I have read many such treatises in model
and full-scale airplane, electronics, and Ham radio publications. As with "A
Radioman's Wife Puts in a Good Word" from a 1951 issue of Radio-Electronics
magazine,
they typically start by expressing frustration of having lost their once-doting
husbands to alternative loves in the form of hobbies (I once saw a boat named "The
Other Woman"). Determined to win back the devotion of their sweethearts, they...
 Most people who have been in the electronics
world for a while know that neon light bulbs* used to be commonly employed as a
"pert-near" voltage regulator reference of between 55 and 65 volts, depending on
the type. The familiar NE-2 has a turn-on voltage of 65 Vac (90 Vdc),
for instance, and the voltage across the terminals remains there with little change
regardless of the current through the bulb - a lot like a Zener diode. Neon bulbs
are also used as non-invasive RF power detectors. Most people probably do not know,
however, that incandescent bulbs also have properties that make them useful for
purposes other than just lighting up a dark space.
Incandescent light bulbs have...
 This newest edition to RF Cafe's *FREE*
Espresso Engineering Workbook was a major bit of work. The ABCD-,
s-, h-, T,- Y- Z- Parameter Conversions worksheet will convert a
2-port
matrix of any of those types of matrices into the equivalent of all the others.
Enter the real and imaginary parts and click the appropriate button. I do not
know of any similar FREE conversion facility. True, the vast majority of
visitors will never need to perform such conversions, but for those who do,
well, here you are. My first exploit with them was way back around 1990 when
writing a DOS program to do a cascade calculation of components whose
s-parameters were known, but needed to be converted to an ABCD matrix for
simpler calculation...
 Since 2000 - that's 20 years - 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...
 Here is Part 14 of a series entitled
"The Saga of the Vacuum Tube," by Gerlad Tyne, that appeared in
Radio News magazine in 1944. Part 1 was printed in March 1943, and Part 22,
the final chapter, was published in April 1946. It could have been a stand-alone
book. If I manage to be able to buy issues with some of the other parts, those will
be posted as well. You might be aware of the origins of the amplifying vacuum tubes,
beginning with the accomplishments of Dr. de Forest and his Audion. As with
most new technologies, progress moved very rapidly once other researchers glommed
on to the concept. Here, Mr. Tyne discusses the development of the "Kenotron,"
"Pliotron"...
 Electronics wizard, repairman, and experimenter
extraordinaire Mac McGregor, as sort of alter ego of author John T. Frye, provides
a brief lesson on electrostatics for his repair shop apprentice wing man Barney
(I don't think his last name was ever mentioned). In this 1973 Popular Electronics
magazine article, Mac had built two types of
electroscopes - one using a pair of pith balls suspended from
silk strings and another that was a cobbled-together version of a gold leaf electroscope.
His motive was two-fold. First and foremost was to accommodate his own interest
in electrostatics, and second to hopefully engender enough curiosity in Barney to
cause him to do a dive into science books...
 Citizens Band Radio (CB) in the United States
grew out of the post-World War II idea that ordinary citizens, small businesses,
farmers, contractors, hunters, motorists, and families should have access to short-range
two-way radio without the technical qualifications required for amateur radio. The
Federal Communications Commission created the Citizens Radio Service in the 1940s,
initially in the UHF region, but CB became culturally important only after the FCC
opened the 27 MHz "11-meter" band to Class D Citizens Radio in 1958. That band,
26.965 MHz to 27.405 MHz today, is what most Americans mean by "CB radio.” CB was
originally licensed. Users paid for an FCC license...
 Robert Taylor, along with inventing the
concept of "super-modulation," also coined the new communications term "Intelligence Transmission Efficiency." It refers in part to the
ratio of power in the intended sideband relative to power in the at least partially
suppressed other sideband and carrier. Admittedly, I have not read this material
enough to fully comprehend the concept of super-modulation, but at least based on
the Fig. 1 waveform, there seems to be an element that adds a DC bias to the
detected signal due to a nonsymmetrical (about 0 Vdc) transmitter modulation by
pumping more power into the positive peaks. I'm happy to be corrected by any
knowledgeable reader. For that matter...
 Robert Taylor claims - without contention
from what I can find - to have invented the concept of "super-modulation," whereby the normal "splatter" created by greater
than 100% amplitude modulation (AM) can be mitigated through use of specialized
circuits. As with many paradigm-changing discoveries, much was made of super-modulation
in the late 1940s through early 1950s, and then it pretty much dropped off the charts.
The cause might have been that the sophistication of circuitry needed to keep everything
tuned and tracking properly to prevent harmonic and sideband was deemed not worth
the trouble once frequency modulation (FM) came on the scene. FM quickly gained...
 It would be more than a decade after the
publishing of this article before the first
direct-to-home satellite television broadcasts would be a reality,
so it shows how long plans were being made for such systems. Rural landscapes are
still peppered with the large vestigial C-band (~4 GHz) satellite dishes, many
with faded eyeballs and other clever (and ugly) artwork on them. Before coaxial
cable was strung beyond suburbs, country dwellers who either could not pull in over-the-air
broadcasts from downtown locations or just wanted more viewing options paid dearly
for satellite service. Equipment and installation costs on early systems could run
into the $30k realm. Today's satellite TV systems use...
 At least in the U.S., laws regarding the
recording of telephone conversations seem to be constantly changing
and vary from state to state. Violation penalties - including imprisonment - can
be severe in both cases. Some states require that all parties in the conversation
be apprised of the recording, while others only require that at least one party
(obviously the one doing the recording) be aware of it. As mentioned in this 1954
"Macs Radio Service Shop" story, some areas require that an audible "beep" be sounded
at regular intervals while recording is occurring. With the ubiquitous use of smartphones
featuring built-in recording capabilities, opportunities for recording and being
recorded are constant...
 Here is an advertisement for Electro-Voice
Manufacturing Company
microphones that I scanned from page 101 of my copy of the February
1943 QST magazine. As with many companies during the World War II
era, this one's theme is the service their products are providing to America's
servicemen. Per the ad: If you were receiving radio messages from men in the midst
of earsplitting battle noises, you'd hear crisp speech undistorted by background
sound effects. Electro-Voice Microphones, in military service, are helping to make
it possible. Similar microphones, designed to achieve such results, will be available
for specific commercial applications ... after our wartime job is done...
 Voltage standing wave ratio (VSWR), often
shortened to SWR in radio work, is a measure of how well a load impedance is matched
to a transmission line. It is defined as the ratio of the maximum RF voltage to
the minimum RF voltage along a transmission line when forward and reflected waves
interfere: VSWR = Vmax / Vmin = (1 + |Γ|) / (1 - |Γ|),
where Γ, the reflection coefficient, is the complex ratio of reflected
voltage wave to incident voltage wave. A perfect match has Γ = 0 and VSWR = 1:1.
An open circuit or short circuit has |Γ| = 1 and VSWR is infinite. In practical
RF systems, VSWR is a convenient scalar indication of mismatch, but it does not
by itself show...
 Who says engineers and scientists have no
sense of humor? This is not an April Fools joke or an attempt to punk you into reading
the story. An Internet browser with strict parental control settings enabled might
even prevent this page from even being displayed. In actuality, the term "G-String Transmission Line" was so dubbed by its inventor, Dr. George
Goubau, as a tribute to his own name - both first and last. Out of an abundance
of caution, I reference the Library of Congress' "G-String" entry for the good
doctor and the device's legitimacy. A drawing similar to Fig. 1 in this
1951 issue of Radio-Electronics magazine can be seen on the chalkboard
behind Dr. Goubau in the LoC...
 Usually, when I read about yet another launching
of rockets from Gaza into Israel, what comes to mind is the barrage of
V1 Buzz Bombs and ultimately the V2 rockets that Germany terrorized
London with during World War II. Although overall not very effective individually,
they did cause brief spells of horror for the localized group of people that were
affected through maiming, killing, or property destruction. The difference between
the Nazi's weapons and Hamas' weapons is that the Germans didn't depend
on other terrorist entities to supply them with their weapons of destruction; they
were brilliant people who had evil intentions of world domination. Hugo Gernsback
writes...
 The 20th Century American electronics industry
produced some of the most influential companies in technological history, from the
laboratories that invented the transistor to the factories that put televisions
in every American home. Yet by the end of the century, many of these
iconic names had passed into foreign ownership through a series of acquisitions
driven by globalization, shifting competitive dynamics, and changing corporate strategies.
Finnish, South Korean, French, Dutch, German, Chinese, Japanese, and other international
buyers acquired what had once been pillars of American innovation. Bell Laboratories,
RCA, Zenith, Magnavox, Sylvania, IBM's PC division...
 Sangamo Electric Company was a "heap" big
name in capacitors in the realm in the middle of the last century. The company always
featured an American Indian in its electronics magazine advertisements, and usually
also included some form of "indian-ese" statements as part of the sales pitch. Of
course such marketing schemes would be vehemently raided and those responsible figuratively
"scalped," if you will pardon the gratuitous expressions. As with using names like
the Washington Redskins, the Atlanta Braves, the Chicago Blackhawks, and the Cleveland
Indians to appropriate and celebrate the bravery and might of the named peoples,
Sangamo implied quality, durability, and reliability...
 Phased
vertical stacks of two or more antennas were fairly common in
the television realm - especially once color broadcasts became more dominant in
the 1950s. Up to 3 dB per additional antenna is possible, but due to various
non-ideal physical parameters (summed phase angle, imperfect antenna geometry, etc.),
realized gain is typically in the 2.5 to 2.8 dB range. Higher signal to noise
ratios were needed to guarantee good color separation with the National Television
System Committee (NTSC) and stereo channel audio separation with the advent of Multichannel
Television Sound (MTS). As you might expect, companies appeared claiming to have
invented physics-defying antennas...
 We take a lot for granted these days with
the seemingly unlimited availability of cheap stuff of all kinds - some of it complete
junk and other of it pretty darn good. That goes for electronics components and
complete products and test equipment, tools, automobiles, appliances, and utensils,
clothing, medical equipment - you name it. Something as simple as a
pistol-type soldering gun can be purchased at just about any hardware
or home store, and at a price that when adjusted back to equivalent money in the
1940s would be amazingly cheap even then. For instance a Weller Soldering Gun kit
from Lowes sells for $39.48 today (less when on sale), which would have been $3.44
in 1947
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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.
 This could be a headline for today, tomorrow,
or from 89 years ago when this article appeared in QST magazine. It was
the latter, following the magnitude 6.4 earthquake that hit the Long Beach, California
region. Per Wikipedia, "An estimated $40M worth of property damage resulted, and
between 115 and 120 people died. Many of these fatalities occurred as people ran
out of buildings and were hit by falling debris." That paled, though, in comparison
to the
magnitude 7.8 San Francisco earthquake in 1906, where massive destruction occurred
and upwards of 3,000 people died. As usual, radio amateurs were some of the first
emergency responders...
 Back in the early days of radio - and then
later television - companies used big-name media personalities to promote their
wares. To a lesser extent some of that happens today as well. Advertisements like
this one for
RCA's Radiotron vacuum tubes appearing in a 1934 issue of Radio News
magazine is typical of what you would have seen in the era. In it, none other than
Bing Crosby was joined by a trendily dressed woman who was rejoicing in her decision
to buy a new radio that contained those newfangled "Micro-Sensitive" receiver tubes.
Radio was considered a mystical entity by most people, and in 1934 there were still
many households that did not yet host a...
 All RF Cafe Quizzes make great fodder for
employment interviews for technicians or engineers - particularly those who are
fresh out of school or are relatively new to the work world. Come to think of it,
they would make equally excellent study material for the same persons who are going
to be interviewed for a job. The subject of
Quiz #16 is Antennas. You don't
need to be an antenna expert to score well, but if you do or plan to work with antennas
and cannot answer a question like, "What does dBi, the most often used unit for
antenna gain (or directivity), stand for?," then maybe it is time for some review...
 Hmmmm.... at the time I marked this
stereo tape playback preamp project for posting I must have had a really good
reason for it, but now I can't recall what that really good reason was. Maybe it
was simply to mark the point in time when stereophonic electronic equipment was
just beginning to be mainstream. Oh well, somebody somewhere will do a Google search
on the topic someday and will be elated to find this. Besides, even though the use
of vacuum tubes and magnetic tape is way outdated, there is a discussion of hi-fi
audio that is still relevant. The article appeared in a 1958 issue of Radio-Electronics
magazine. Thanks for your indulgence...
 While reading through these vintage electronics
magazines, I often wish I could have lived in the era and owned an
electronics repair shop. Radios, televisions, record players, tape
recorders, amplifiers, etc., were very serviceable with plug-in vacuum tube
active components and point-to-point wiring with all leaded passive components
(capacitors, resistors, inductors, lamps, etc.). I know this from first-hand
experience working on a 1960's air traffic control radar system while serving in
the U.S. Air Force. As with today, servicemen often get a bad rap undeservedly
because of the low morals of some fellow practitioners. While it is
unfortunately true that bad eggs...
 Maybe it isn't so anymore, but according
to Centralab the ceramic raw materials available in abundance in America were electrically
superior to those being used in Europe since the early 1900s when German scientists
first discovered the dielectric properties of the material. Ceramic capacitors represented
a major advance in capacitor technology over liquid and paste dielectric types in
most areas of electrical and mechanical specifications such as vibration, aging,
vibration and shock, temperature, value stability, voltage and current handling,
etc.
Centralab ran this advertisement in Radio & Television News magazine
spelling out all the...
 With few exceptions, I, RF Cafe webmaster
Kirt Blattenberger, have for more than two decades designed a custom crossword puzzle
every week for the benefit of website visitors. This
Electrical Engineering Theme Crossword Puzzle was created for July 10th,
2022. All crossword puzzles use a personally built dictionary of thousands of
words and clues related to RF, microwave, and mm-wave engineering, optics,
mathematics, chemistry, physics, and other technical subjects. As always, this
crossword puzzle 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...
 Many thanks to RF Cafe visitor Michael M.
for sending me a note about a very handy RF propagation software tool provided free
of charge by the French organization Centre National d'Études Spatiales (CNES, National
Centre for Space Studies). The
PROPAGATION dynamic
link library (DLL) contains functions to compute propagation losses according
to ITU-R P.† recommendations. Versions are available for both 32- and 64-bit
Windows and Linux operating systems, as well as for the C and Visual Basic programming
languages. Very conveniently, the DLL functions can be referenced from within an
Excel spreadsheet as well*, and a demo...
 My father used to refer to the "sweet-voiced
lady predicting the weather over and over again" as my girlfriend because I would
call the "WEather 6-1212" phone number (936-1212) so often. It really wasn't
because I was infatuated with her voice, it's that I was obsessed with weather forecasting.
Most of my free time as a kid and teenager was spent building and flying model airplanes
and rockets, and at eighteen years of age I began taking full-size aeroplane flying
lessons, so my world revolved around a zone extending from terra firma up to about
5,000 feet AGL. This collection of communications news items in a 1940 edition of
National Radio News...
 In this 1953 QST magazine article, 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)...
 Cooling devices based on the Peltier effect
were first demonstrated by French physicist
Jean Charles Athanase Peltier when he noted the presence of heating or
cooling at an electrified junction of two different conductors types (opposite
of a thermocouple). Widespread commercial use depended on finding efficient
materials that could be produced inexpensively. Music synthesizers, to be
practical, needed to await the availability of miniaturized electronics like
transistors and memory elements. Light amplification similarly depended on
affordable sources to be anything more than a laboratory curiosity. Fortunately,
by the mid 1950s such entities were becoming...
 By 1966 the dominance of vacuum tubes, particularly
in new products, as stated by Electronics World magazine editor William Stocklin,
"...is gradually passing behind us." The
Transistor Replacement Problems highlighted in this article refer primarily
to finding second (or third or more) sources for transistor types already designed
into existing products as semiconductor manufacturers move on to new and better
(often much better) devices. There was little motivation for companies to dedicate
scare resources to making low volumes of legacy devices just to service radios,
televisions, phonographs, etc., which, to be honest, they probably preferred...
 What do General Curtis LeMay, Arthur Godfrey,
Herbert Hoover, Arthur Collins all have in common? They were
Ham radio operators. A lot of famous people were/are Hams, with these and a
few other notables mentioned in this March 1958 edition of Popular Electronics
magazine. Conspicuously missing is one of modern day's most renowned Hams, and
that's Walter Cronkite, KB2GSD (died in 2009). His broadcast career stretched
back to World War II, so he was definitely around long enough. Maybe the author
just didn't know; after all, he couldn't just look it up on the Internet or in
an FCC computer database. By now you probably know that actor...
 The
medical x-ray machine shown here reminds me of the "Illudium Q-36 Explosive
Space Modulator" contraption Marvin the Martian wanted to use in "Hare-Way to the
Stars" to disintegrate the Earth (because it blocks his view of Venus). Of course
our hero Bugs Bunny thwarts his plan, whereupon Marvin asks, "Where's the kaboom?"
Can you imagine being fraught with cancer and getting strapped into a chair with
that huge hypodermic-needle-looking thingy pointed at you, as shown in this 1959
issue of Popular Electronics magazine? The Caduceus sword in the pic doesn't help
matters, either. The trauma of such an experience might have been worse...
 It took a couple times reading through this
"Rectifying
Without Rectifiers" article to get the gist of what author H.B. Conant
was talking about. He begins by pointing out the negative aspects of using nonlinear
metallic rectifiers in a bridge circuit for an electric meter, then goes on to describe
an improved "translator" circuit that uses - wait for it - nonlinear metallic rectifiers
(or nonlinear resistors made of Thyrite material). If my interpretation is correct,
basically the new and improved circuit incorporates a bias voltage that forces the
nonlinear element (be it a metallic rectifier or a nonlinear resistance) to operate
in a region which passes a higher current level to the meter... |
