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 These two advertisements appeared in the
July 1935 edition of QST. Bliley Electric is still in business here in
Erie, Pennsylvania as
Bliley Technologies. They make crystals and frequency sources.
Gross Radio has been out of business for quite a while. I included it mainly to
illustrated how large radio transmitters used to be - these things were installed
in people's attics and basements back in the day. This particular model, the
CB-100, is a "100-Watt Radiophone & C.W. Transmitter completely housed in an
entirely enclosed floor rack of ingenious design." It operated in the 1.7, 3.5,
7 and 14 MHz bands. For comparison, iCOM makes a 1 kW power amplifier today
covering those bands...
 Dr. Lee DeForest might have had something
like National Public Radio (est. 1970) in mind when he penned this article in 1933.
In it, the famous vacuum tube amplifier inventor lamented and criticized the commercialization
of broadcasts because of all the paid product announcements (aka commercials) that
had been steadily increasing over the years. He also was critical of the "hit-or-miss,
higgeldy-piggeldy mélange program basis" of programing; i.e., the same station playing
a mix of jazz, opera, swing, syndicated story-telling, etc. The good doctor did
not elaborate on where funding for such dedicated, uncorrupted broadcasts would
originate if not from paying advertisers, and I do not recall ever reading about
a DeForest Radio Network paid for by his vast fortune. I don't like commercials
any more than the next person, but a company deserves time to pitch its products
and/or services if it helps deliver a source of entertainment to you that...
 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. 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...
 John T. Frye's monthly "Mac's Radio Service Shop" techno-drama, written in story form
- was usually an incognito lesson on circuit functionality or troubleshooting, how
to deal with customers, industry regulations and news, or an introduction to new
components and equipment. As the "Unusual New Equipment" title suggests, this time
Mac described a few new items added to the service shop to aid in their work. Often
when reading one of the episodes, I do a Google search on specific components or
equipment mentioned in the article. He describes a special-purpose CRT (Sylvania's
new 5AXP4 Television Receiver Check Tube) that could be used universally for troubleshooting
in place of a wide variety of installed picture tubes. I found one for sale on eBay
for $39.95. There is not much you cannot find on eBay if you watch long enough...
 This is a different type of
electronics-related quiz from Quizmaster Robert P. Balin.
Mr. Balin created many monthly quizzes for Popular Electronics magazine.
Here you are provided a series of images and a list of men's first names, and you
need to match the image to the name. There are nine in all. Sure, it's kind of hokey
(especially B and I), but it is a good end-of-the-work-day challenge challenge to
help pass the time until the weekend begins...
 While not a second-hand store junkie, I
do like to occasionally make the rounds of the local Salvation Army, Goodwill, and
other independent shops to see what kind of relics are donated. Since eBay, Etsy,
and their kind have gained immensely in popularity, it is getting harder to find
anything useful other than clothes and kitchen wares. A few months ago Goodwill
had a 1910s vintage
cabinet -style Edison disc phonograph (as opposed to wax cylinder)
that was in very good condition, complete with a handful of styli and a couple old
records. The original finish over smooth mahogany and burl veneers had only a few
scratches and could easily be polished to look practically new. The metal hardware
could have stood a fresh coat of black paint due to nearly a century of oxidation.
Even the original nomenclature plate looked factory-new, and a clearly legible paper
plaque...
 Bell Labs, having been responsible for creating
the first positive amplification point contact transistor just before Christmas
1947, continued to lead the way in semiconductor research and new product announcements
for many decades. This little tidbit was tucked away at the bottom of page 120 in
the May 1954 issue of Radio & Television News magazine. It reported on "the
purest substances in the world" being created there in the form of 99.99999999%
(aka 10N)
pure germanium crystals, which are used as seed for growing boules
for device production. That's one rogue impurity atom in ten billion germanium
atoms. Modern monocrystalline silicon boules are typically 7N or better...
 This
Attenuator Calculator
is probably unlike any you have seen. Not only does it calculate resistor values
for both balanced and unbalanced Pi and Tee topologies, but it also calculates the
power dissipated by each resistor, and calculates the input and output VSWR when
1% tolerance resistors are used rather than ideal values. Another page provides
all equations and schematics for all four configurations.
 Like so many things in life that
we take for granted - aspirin, automatic clothes washers, drill
motors and bits, eyeglasses, rifles, bicycles, transistors, to name a few - we rarely
think about the effort that went behind the end product that is now enjoyed. Even
relatively simple devices like scissors are the result of someone saying to himself
or herself, "Self, I need something to make cutting fabric and paper and hair simpler
and neater, so what might that thing look like?" Then, after making a working prototype,
improvements are made based on empirical testing from usage, improvements are made
in the form factor, materials, size, etc., until evolution results in what can be
purchased today. If you have ever been in a product design cycle, either privately
or corporately, then you know the process well...
 Found in what is the first issue of
Electronics Illustrated magazine that I have bought are these Amateur radio
related comics entitled, "Over and Out." The cartoonist's signature is simply "Rodrigues,"
which according to a Google search might be Charles Rodrigues (who also contributed
to other tech magazines as well as to National Lampoon). I have to admit
to needing to look up the "Yanqui aggressors" thing on the one comic, and then it
made sense: Yanqui= Yankee. The last comic with the parrot is pretty funny; it's
sort of the Ham radio equivalent to an auto-repeat telephone dialer like what you
would use to call into a radio show during a listener contest...
 During World War II, the government
created a specification for military-grade cable and assigned the designation RG-#/U, where "RG" stands for Radio Guide and the "U" stands
for Utility. The "dash number" was sequentially issued and has no bearing on the
characteristics of the cable. Founded in 1902 in St. Louis, Missouri, by Joseph
Belden, the eponymously named company has been and continues today designing and
manufacturing coaxial cable. Most of the RG-x/U coaxial cable types displayed in
this 1951 Radio & Television News magazine advertisement are still
being used today, in particular the very familiar RG-58/U (50 Ω), RG-59/U (75 Ω),
RG-8/U (50 Ω), and RG-11/U (75 Ω)...
 Welcome to the RFCafe
Isolators &
Circulators Quiz, a technical overview focused on non-reciprocal microwave components.
These specialized devices are the primary tools used to protect sensitive signal
sources from reflected power and to route signal flow in multi-stage RF systems.
Whether you are isolating a high-power transmitter from a high-VSWR antenna, developing
duplexers, or optimizing the signal isolation between cascaded amplifiers in a precision
measurement setup, a solid grasp of circulator and isolator physics is essential.
This assessment addresses the fundamental properties of ferrite-based non-reciprocal
hardware, including insertion loss, port-to-port isolation, power...
 How far do you commute each day for the
privilege of doing your part to push back the frontiers of technical ignorance and
to boldly go where no engineer - or technician - has gone before. Do you know what
the cost equates for you each year? This handy-dandy infographic lays out some
gruesome
numbers. Those with a weak stomach probably should pass on viewing this one.
Here's a hint at what you will see: See that big $795 in the thumbnail image?
That's the average cost per year for commuting -- per mile! Yessiree, if you
live just 10 miles from work, you're losing nearly $8,000 per year, depending
on you automobile type, on gas, tires, maintenance, devaluation, and loss of your
personal time (which is valuable, after all). Back in the early 1990s I drove about
45 miles each way...
 Joe Cahak, owner of Sunshine Design Engineering
Services in Ramona, California, has written a white paper entitled, "Measuring Semiconductor Device Input Parameters with Vector Analysis."
This article covers a recent test experience that utilized some thinking about the
test fixture, the bias requirements and the device mounting and special calibration
offsets needed to de-embed the test fixture response from the device response within
the test fixture. The device also had to have bias on several ports simultaneously.
We had to establish a "reference plane" within the fixture, from which we can use
the Vector Network Analyzer's Port Extension or Phase Offset to dial out the
distance from our 1 port calibration reference plane to the point of short reference
within the fixture. With this phase offset compensation we can then measure...
 Author Howard Wright takes the opportunity
here to distill the
concept of modulation down to its basic operation while dispensing
with the garbled mix of "graphs, formulas, charts, vectors, diagrams, and Greek
letters which often enter into various discussions of modulation". Wright describes
how to the uninitiated radio dial spinner, the culmination of events occurring behind
the scenes in an AM reception is akin to knowing "that, to be reproduced, the picture
[in a magazine] was broken down into its primary colors, if all we had to go by
was the original print and the magazine?" That is a very apt comparison...
 Alliance Test Equipment sells
used / refurbished test
equipment and offers short- and long-term rentals. They also offer repair, maintenance
and calibration. Prices discounted up to 80% off list price. Agilent/HP, Tektronix,
Anritsu, Fluke, R&S and other major brands. A global organization with ability
to source hard to find equipment through our network of suppliers. Alliance Test
will purchase your excess test equipment in large or small lots. Blog posts offer
advice on application and use of a wide range of test equipment. Please visit Allied
Test Equipment today to see how they can help your project.
 Benjamin Franklin is famous for his kite-flying
experiment whereby he "discovered" not electricity (as many people believe), but
that
lightning is a form of electricity (most people thought it was
a jet of gas). A lesser known fact about Mr. Franklin is that he invented the
lightning rod after realizing the electrical nature of lightning. His understanding
of electric fields facilitated an implementation whereby hefty iron cabling interconnected
a tall, pointed rod installed at the tallest point on a building and a spike driven
into the ground. Lightning typically strikes the object that is the shortest distance
(in terms of electrical field strength) from it because the discharge can begin
at the lowest voltage. The presence of the grounded lightning rod above the highest
point on a structure effectively brings that point all the way down to ground level...
 These "Radio Term Illustrated" comics from vintage Radio-Craft
magazines are some of my favorite tech-themed comics. Most were drawn by Frank Beaven
in response to suggestions / requests by magazine readers. The one here from page
80 entitled "Crystal Gazing" was done by Franklin Folger. If you didn't know
that it appeared in a 1947 edition, you might assume it depicts a Steam Punk themed
LCD computer monitor mounted atop a Morse code straight key, but of course it is
not. At the time, cathode ray tubes (CRTs) were the only form of video display,
and while small like the one in the drawing (and round, unlike the drawing), they
were far from flat. Little did the artist suspect that his "Crystal Gazing" idea
meant to imply a type of mystic's medium for seeing...
 The big graphic with Figures 1 through 17
reminds me of the kinds of study sheets I used to make when cramming for exams in
my college circuits courses. Did I ever tell you about the wise guy instructor I
had for my first Circuits class at the University of Vermont? Anyway, this article
provides an introductory level treatment of using
negative feedback in amplifier circuits. Lots of illustration
and formulas are included. Frequencies are at baseband, so you won't learn any
secrets for high frequency amplifier stabilization, but then even RF and microwave
circuits eventually need to convert down to baseband at some point for sampling
or for use as audio or video...
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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.
 Light-emitting diodes (LED's) were still relatively
new to the scene of solid state electronics in 1969 when this article was published in
Electronics World Magazine. Two engineers from RCA Electronic Components wrote
to describe the state of the art in LED physics and features. The pair's prediction that
the LED would become "a light source that can be used for indication and display wherever
tungsten-filament, incandescent lamps are used" did not yet have enough insight into
the devices to know that four decades would pass before their prediction would be realized.
LED's have...
 Just yesterday I posted an article titled "Understanding
Your Triggered Sweep Scope," that appeared in the May 1973 issue of Popular Electronics,
so I figured this "Scope-Trace
Quiz" would make a good compliment. It is from a 1965 issue of Popular Electronics.
Driver circuits all include a sinewave source in parallel with a series resistor and
diode, connected to the vertical and horizontal o-scope inputs. The resulting Lissajous
waveforms resemble hands on a clock face thanks to the diode. Shamefully, I only scored
70%, but in my own defense I'll say I didn't take the time to draw them out on paper.
Pay careful attention to the scope...
 All oscilloscopes have some ability to trigger
the display sweep on the waveform being measured. Some models provide more options than
other to the user for controlling how the
sweep is triggered - positive-going edge, negative-going edge, high or low repetition
rate, frequency, specific voltage level, from the AC line, or even from an external source.
Without control over the trigger source, repetitive waveforms would be "walking" across
the screen, random signals and very long interval signals would be missed, and complex
signals would be a garbled mess. This article gives an introduction on how o-scope...
 Here is an area of electronics that will be foreign
soil to most Gen-Xers and Millennials -
troubleshooting your malfunctioning radio, phone, television, garage door opener,
kitchen appliance, etc. Admittedly, most modern devices are designed and priced to be
replaced rather than repaired. Relatively cheap product replacement and service plans
keep them going for a year or three until they are obsoleted by newer devices with whiz-bang
additional features. However, there are many of us still around who are born to tinker
and are too cheap to bear the thought of throwing something away before at least attempting
to fix it. I have written often about how many...
 It is hard to imagine a time when integrated circuit
(IC)
comparators were a big deal, but as recently as 1973 when this article appeared in
Popular Electronics, they were new to a designer's bag of tricks. Prior to an
IC solution, comparators needed to be constructed from opamps and a handful of peripheral
biasing components. As with other integrated circuits, not only does the overall price
go down, but so does circuit board real estate, cost, temperature variability, and electrical
parameter variance between devices. The first comparator circuit I remember designing
was a temperature sensor that went in an oven used for curing the potting...
 It appears that maybe Abraham Lincoln had a son
who was an electrical engineer working at Motorola Semiconductor back in the 1960's.
Put glasses on Honest Abe (I did) and author Irwin Carroll's a spitting image of the
Great Emancipator. Seriously though, this article is a great introduction to the fabrication
and use of variable
capacitance (aka varicap and varactor) diodes. They have been - and still are - used
widely for electrically tunable oscillator and filter circuits. Topics such as temperature
and figure of merit ("Q") are discussed as well. This edition of Electronics World
ran a series...
 Being the birthday of Dr. Robert W.
Wilson, there is no better occasion to post this article about the "sugar-scoop" antenna used by the two Bell Telephone Labs engineers
(the other being Dr. Arno A. Penzias) who serendipitously discovered the cosmic
microwave background radiation (CMBR) believed to be a signature of "The Big Bang."
The pair were investigating an unexplained hiss in the background of the very low
noise receiver attached to the antenna. That microwave energy was constant and came
from all areas of the sky, regardless of where the antenna was pointed. They eventually
deduced that the signature was consistent with...
 Hewlett Packard introduced their electronic
HP-35 Scientific Calculator in 1972. It was not the world's first
pocket-size electronic calculator - that distinction went to the Busicom
LE-120A. However it was the first to be designed for the science, engineering,
and financial communities with its many built-in math functions. Its use of
Reverse Polish Notation might have scared off many would-be users who were
easily confused by anything other than the traditional notation (algebraic) that
mimics written form; i.e., 2 + 3 = 5 (ALG), as opposed to 2 3 + [=]
5 (RPN). Wisely, HP made both modes selectable. Reading through the HP-35 manual
makes it evident that this calculator was not for the feint of heart as it
presents concepts like memory stacks, imaginary numbers...
 I was first introduced to the concept of
receiver noise figure at the start of my engineering career in
1989 at General Electric AESD in Utica, NY. During my four years in the U.S. Air
Force working on airport surveillance and precision approach radars, I do not recall
having ever heard the term noise figure or noise temperature. We did signal to noise
and signal sensitivity measurements as part of the normal maintenance, but the terms
never arose. Ditto for my courses at the UVM. We never did cascade parameter calculations
for noise figure, intercept points, compression points, etc. That is primarily the
realm of practicing...
 At least 10 clues with an asterisk (*)
in this
crossword puzzle are pulled from this past week's (1/1 - 1/7)
"Tech Industry Headlines" column on the RF Cafe homepage
(see the Headline Archives page for help). For the sake of all the avid cruciverbalists
amongst us, each week I create a new technology-themed crossword puzzle using only
words related to engineering, science, mathematics, chemistry, physics, astronomy,
etc. Enjoy...
 At least 10 clues with an asterisk (*)
in this
technology-themed crossword puzzle are pulled from this past week's (2/19 - 2/23)
"Tech Industry Headlines" column on the RF Cafe homepage (see the Headline Archives page
for help). For the sake of all the avid cruciverbalists amongst us, each week I create
a new technology-themed crossword puzzle using only words from my custom-created related
to engineering, science, mathematics, chemistry, physics, astronomy, etc. Enjoy...
 When I first began designing circuits in
the 1990s using
active filters, the upper frequency was limited to a few tens
of kHz because of the gain-bandwidth product of the available amplifiers. That made
them useful in baseband circuits, but that was about it. There were also issues
with the noise figure and intercept points and intermodulation product levels. Today,
you can get fully integrated and programmable active filters which operate at tens
of MHz and beyond, and with much better RF-type specifications. That makes them
useful in low intermediate frequency (IF) circuits as well as at baseband. BTW,
this article is one of about ten dealing with filter types in...
 Here is a unique type of article from a 1974
issue of Popular Electronics. Author Ralph Tenny presents a
poor-man's environmental test chamber constructed with a Styrofoam
picnic cooler, a dry ice sump, a heater, a thermocouple, and a bunch of input/output
ports for making electrical measurements. While working on my senior project at
college - an electronic remote weather station - I needed to verify functionality
up to 150°F and down to 0°F. Having the Torture Box would have been handy, but instead
I used the kitchen oven and freezer with the interconnect cable mashed between the
door gasket and frame. Unfortunately I don't have any...
At least 10 clues with an asterisk (*)
in this
technology-themed crossword puzzle are pulled from this past week's
(2/5 - 2/9) "Tech Industry Headlines" column on the RF Cafe homepage (see the Headline
Archives page for help). For the sake of all the avid cruciverbalists amongst us,
each week I create a new technology-themed crossword puzzle using only words from
my custom-created related to engineering, science, mathematics, chemistry, physics,
astronomy...
Please welcome
Joseph "Pat" Dunagan
to our exclusive list of former and current USAF radar techs. Pat is the first officer
amongst us, so that unofficially makes him the ranking member on the page - not
including 5CCG commander Col. John Kopsick, who did not actually maintain equipment.
Along with time in the regular Air Force, he also did time as Chief of Maintenance
in the Reserve 55th CBCS mobile combat outfit at Robins AFB where I was stationed.
He had responsibility for MPN-13/14 and TPN-19 radars... |
