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 If you were hanging around here in 2014,
you might recall a paper I published titled, "Drone-Based Field Measurement System™ (dB-FMS)™." Since that time,
I have seen news items about a few companies using drones to measure antenna radiation
patterns and many more others are coming online all the time. Some amazing working
systems have been implemented that seem to perform very well. I'm not saying
they got the idea from my article because more than one person can have the same
brilliant idea ;-). It's just good to know that my concept had some merit in
the real world...
 My
Vise-Grip pliers have performed a lot of hard duty over the decades.
Many rusted nuts and bolts would still be unremoved if it weren't for their
sharp, corrugated locking jaws. I have 10", 7", and 4" w/cutter, and 6" long nose
models. These are all manufactured under the Petersen Manufacturing Company name,
before they bought Irwin, who now manufactures Vise-Grips. Even high quality tools
eventually show signs of wear after decades of use and abuse. A few of mine had
jaws worn down to the point where they no longer would "bite" into the bolt head
or nut being clamped. I was about to buy a couple new pairs of Vise-Grips, but then
wondered if I could recondition the jaws to put the pointed shape back on the jaws
with a triangle file. Being hardened steel, a lot of times a standard file will
barely scratch the surface, but in this case I managed to dress the jaws of four
pairs of Vise-Grips before the file (double taper triangle) got dull...
 "Stratovision" sounds about as serious as "Wonkavision," but unlike
the candy maker's fictional machine that transported chocolate bars across the
room, Stratovision was in fact a serious proposal. It was an early form of satellite
television. Since orbiting communications satellites would not be practical for
another decade, Westinghouse devised a system in 1945 using aircraft flying at high
altitude to relay television signals. Engineers calculated that 14 airplanes circling
at 25,000 feet could provide coverage to 78% of the country. By 1950 they had a
working system, but needless to say (because nobody has ever heard of it... except
you, now), the concept ultimately did not pan out. It was not because the system
failed to work as designed, but because there was not enough demand...
 Werbel Microwave is a manufacturer of
RF directional and bidirectional couplers (6 dB to 50 dB) and RF power
dividers / combiners (2- to 16-way) with select models operating up to 26.5 GHz
and 100 W of CW power (3 kW peak). All are RoHS and REACH compliant and
are designed and manufactured in our Whippany, NJ, location. Custom products and
private label service available. Please take a couple minutes to visit their website
and see how Werbel Microwave can help you today.
 According to this full-page advertisement
in the June 1955 issue of Radio & Television News magazine, Bell Telephone
Laboratories was responsible for designing and fielding "waveguide pipe," aka flexible circular waveguides. According to
other historical sources, both George Southworth of Bell Telephone Laboratories
and Wilmer Barrow of the Massachusetts Institute of Technology (M.I.T.) independently
and simultaneously developed circular waveguide, but the early devices were rigid
pipe rather than being fabricated from tightly wrapped, insulated wire that permitted
it to be bent rather than requiring separate corner and offset pieces. Insertion
loss and VSWR is typically not as good as with rigid waveguide, but the ease of
installation in many situations justifies the poorer electrical performance. Bell
Telephone Laboratories was responsible...
 Having recently struggled a little with
re-stringing the dial cord on a vintage Realistic (Radio Shack) Patrolman-50 Radio,
it really became apparent why the
Sams Photofact Folders were of such value to electronics servicemen.
Unlike the tangled mess of dial cord shown in the ad, I had the advantage of being
able to carefully open the chassis and photograph the routing and wrapping of the
broken dial cord around pulleys and shafts. Even so, a lack of experience required
some trial and error to get the tensioning correct. No doubt many unqualified radio
owners attempted to fix their own broken dial cords prior to breaking down and committing
to spending a few bucks to have a pro do it correctly. The tight quarters in my
portable radio had me using tweezers to do some of the routing...
 My mother loved
Norman Rockwell paintings for their ability to get to the heart of Americana.
She was an avid collector of books on Rockwell and decorated plates for display
- as avid as one can be on my newspaper classified ad manager father's feeble
salary, anyway. I, too, have a great appreciation for Rockwell's great talent
to choose his subject matter and models and to, when fitting, include a nearly photographic
level of detail within. The Saturday Evening Post magazine featured many of his
works spanning from 1916 until 1971 - from the middle of World War I and on
through World War II, Korea, and Vietnam. Summer, spring, fall, and winter;
Christmas, Easter, Veteran's Day, President's Day, Mother's Day, New
Year's, and other annual events; experiences of love, happiness, joy, surprise,
sadness, and a host of other emotions...
 Time to put on the thinking cap again for
three more "What's
Your EQ?" circuit challenges, compliments of Radio-Electronics magazine
in May 1962. The first is a classic "black box" type problem which, from reading
its description, involves some sort of resonant circuit. that's all I'll say on
that. The next, called "An Easy One?" should, by the way it is drawn, be a clue
that it might be easier to solve if you re-draw it to make a familiar-looking circuit.
Hint: Summons the spirit of Sir Charles Wheatstone. Just the name of the last one,
"Iterative Network," is enough to induce a cold sweat. As with most of these "What's
Your EQ?" problems, successful completion of a first year college circuits course
is plenty to get through them. A few are better attempted by people with hands-on
experience troubleshooting circuits, but don't let that scare you off...
 KR Electronics has been designing and manufacturing custom filters
for military and commercial radio, radar, medical, and communications since 1973.
KR Electronics' line of filters includes lowpass, highpass, bandpass, bandstop,
equalizer, duplexer, diplexer, and individually synthesized filters for special
applications - both commercial and military. State-of-the-art computer synthesis,
analysis, and test methods are used to meet the most challenging specifications.
All common connector types and package form factors are available. Update: KR Electronics
has been acquired by NIC, where KR Electronics'
legacy of quality and innovation will continue to thrive, offering the same trusted
products and services under NIC's leadership. For over three decades, NIC has delivered
high-quality component performance and reliability, ensuring the successful deployment
and operation of our clients' mission-critical solutions. Designed and manufactured
in the USA. Please visit NIC today to see how
we might be of assistance.
 Roger McCraw sent me these photos from his
assignement in U-Tapao, Thailand, cicra 1973. I submitted a couple of the images
to AI for colorization - amazing! Says Roger, "The pictures were taken at U-Tapao,
Thailand and are dated April 1973. I was there from Jan 73 till Jan 74
and was a 30351 in the 1985th Comm Squadron. Since I was the newbie I was selected
to change the light bulbs so I decided to give a Nixon peace sign for the photographer.
The MPN was on a turntable so it could service both approaches to the runway. The
ATC displays were in a trailer that was attached to a building, it was just to right
of truck in picture. I only remember the name of one person because his name is
listed on TWS website. He bought a four function calculator...
 This installment of the After Class series
in the December 1957 edition of Popular Electronics deals with inductors.
It is a beginner-level introduction to how
reactive components behave in circuits. For some reason the concept
of magnetism's influence on electrical current (present with inductors but not
capacitors) seems to be more difficult to comprehend than that of electrons, even
though James Clerk Maxwell shows in the mid 1800s that the two phenomena are interrelated.
I am tempted to say that back in the 1950s when this article appeared, people were
less familiar with the relatively new concept of electronics, but in thinking about
it, your typical 2019 reader is probably even less likely to know anything at all
about electronics or the way basic components work. I would bet that maybe 1% could
even tell you the difference between AC and DC current...
 Not very long ago I mentioned
Jean Shepherd (original assignee of W9QWN and later K2ORS call
signs) as being one of my favorite old-time radio broadcasters (1960s-1970s). Jean
was famous for recounting stories of his own life and for reporting news of the
time in a way that could hold you in rapt attention from beginning to end. His humor,
wit, and command of the English language was acknowledged by his contemporaries.
If you listen to enough of his broadcasts you will notice the frequent mention of
electronics and his experiences as a licensed amateur radio operator beginning at
a tender young age. Just recently I listened to him recount his first day in high
school when a SNAFU in the computer-generated (must have been a UNIVAC) class schedule
mistakenly had him reporting to the girls' swimming pool...
 I was born in the era of screw-in glass
fuses in household electric service panels. There was always a supply of replacements
in the cabinet above the stove. Sometime around 1978, prior to enlisting in the
USAF, I replaced the fuse panel with a Square D circuit breaker panel - a skill
learned through four years of electrical work. In the Air Force, I worked on a 1950s
era air traffic control radar system which consisted of many chassis assemblies
having fuse holders on their front panels. The racks themselves had a circuit breaker
panel, but it was a retrofit from sometime in the early 1970s. That was my introduction
into the wide variety of cylindrical glass fuses - high and low voltage, normal-,
slow- and fast-blow, time delay, etc. I learned of the reason why circuit designers
employed each type, and always used exact replacements when possible. Later, as
a circuit and systems design engineer myself, I always was careful to specify the
most
appropriate fuse type. This 1960 article in Radio-Electronics magazine
is a good primer on fuse handling...
 Being that this
Circuit Quiz appeared in a 1966 issue of Radio-Electronics magazine,
the amplifier components shown are transistors, rather than vacuum tubes. I have
to admit to not doing very well on it. One of the challenges is first determining
what the intended function of the circuit is supposed to be, then you figure out
what is wrong with it. Spoiler alert: I'm going to use circuit A as an example.
It is declared to be a voltage regulator circuit, and the deficiency is the lack
of a stable voltage reference. The architecture is typical of a voltage regulator
with the common base setup used to increase the current supply. However, there is
no reason to necessarily assume the DC IN is not itself already regulated, and the
function if merely to increase the current supply capacity. If that is the case,
then the circuit seems sufficient as shown. Maybe the fact that there is no problem
otherwise should tell you make an assumption about the designer's intention and
look for something that would be suspect under that condition. Anyway, that's my
excuse and I'm sticking with it ;-)
 This rather extensive article from a 1947
issue of QST magazine describes the method used by author Philip Erhorn
to experimentally determine optimum
spacing for the parasitic elements of his antenna. Unless you
have electromagnetic field simulation software available for designing antennas,
the procedure typically involves beginning with published formulas for element length
and spacing, then resorting to a cut-and-test method of finding a combination that
works best for your installation and goals. Almost certainly no two Hams end up
with identical configurations because differences in terrain...
 Since this is a presidential election year,
I figured it would be a good time to post a tongue-in-cheek- story that appeared
in the November 1952 issue of QST magazine about a fictional American president
J. Willoughby Winkelspoof. The American Radio Relay League
(ARRL) always has been and still is apolitical, so don't take seriously anything
you read here. If you are an astute follower of politics, you might pick up on the
nuances woven into the story, and might even marvel on how much the political landscape
has changed in the half century since Pres. Winkelspoof graced the Oval Office...
 This is Part II of a 3-part series of articles
on
magnetostriction devices. At audio and low IF frequencies, the
use of ferrite elements to construct relatively high-Q resonant circuits for filtering
was a big deal in the middle of the last century. Although not presented in this
article, design formulas and tables were published to implement the familiar Butterworth,
constant-k, Chebyshev, Gaussian, and other types. Tuning, particularly for higher
order filters, could be a chore since it involved a cut--and-try method on the ferrite
rods. However, that is what was available in the day, and it evidently worked well
enough to be worth the trouble for desired...
 Electronics World magazine often published
electronics-themed crossword puzzles. Unlike RF Cafe engineering crosswords
I created for two decades that use only technical words and clues, this one does
include some unrelated words. A couple clues I was surprised to see pertain to radar;
e.g., 32A: Small visible mark on a radar or scope screen, and 44A: Identification
Friend or Foe. Some words require a familiarity with technology of the era, but
you shouldn't have much trouble. You'll need to print this out on paper to work
it..
 Advances in
transformer technology are driven by the need for miniaturization and efficiency,
particularly in airborne and high-frequency military equipment. By optimizing core
materials and fabrication, engineers can significantly reduce the weight and physical
dimensions of transformers. A major technical milestone highlighted in this 1964
Electronics World magazine article, was the development of grain-oriented
silicon steel, which, through precise crystal alignment, offers superior magnetic
properties and reduced energy losses compared to traditional soft iron. Modern design
further mitigates power loss from hysteresis and eddy currents by employing thin,
insulated laminations...
|
 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.
 Robert Balin created many quizzes for
Popular Electronics magazine back in the 1960s and 1970s. This particular "Electronic
Numbers Quiz" presents various objects and your challenge is to match one of
the provided numerical values to each item. For example, a tuning fork is most commonly,
in the Western world, associated with a certain frequency for tuning musical instruments
(electronic and mechanical). As is often the case, being familiar with the "standards"
of the era is helpful on a few of the items like the tuning capacitor and the IF
transformer, but you should be able to eliminate some options by knowing the impedance
of the twin lead transmission line and the phase relationship of current and voltage
in a pure inductance...
 This installment of "Stereo
Scene" was the 12th in a series run by Popular Electronics magazine
in the early 1970s. As mentioned previously, stereo equipment was a big deal in
the 1960s and 1970s. Amazingly - or maybe not amazingly - some of the issues of
the day have persisted through today's audiophile community. One of the most fervently
debated topic is whether audio power amplifiers that use vacuum tubes produce higher
quality sound than do transistorized power amplifiers. The pro-tube argument holds
that the physical flow of electrons and the ability of metal internal components
to vibrate microscopically in response to signals imparts a quality to the output
that rigid semiconductors cannot. Many attempts at designing circuits to artificially
add such "quality" to transistorized amplifiers...
 Television interference (TVI) was a major
concern for amateur radio operators back in the heyday of broadcast TV. Other than
radio broadcasts, magazines, and newspapers, it was the only other major form of
media available; there was no Internet. Even the lowest priced TV sets represented
a significant portion of a typical family's disposable income. There was no government
handout program that provided every household with a television set and antenna.
Consequently, people were very irritated by nearby electrical or electronic equipment
that dared to interfere with their reception - and rightly so. Ham radio operators
broadcast on bands that were fairly well separate from the TV channel frequencies;
however, harmonics and intermodulation products often fell in the TV bands, and
that caused real problems with the public perception of amateur radio. Articles
like this were aimed at helping people tame...
 Power, energy, force, and work are all
physical entities whose definitions are often incorrectly interchanged. As with
most cases in physics, knowing the unit associated with each entity is a way to
remember what it represents. For instance, force is fundamentally understood as
a mass being acted upon by an acceleration - whether it be gravity or motion. Its
SI units are kg·m/s2 (newton, with dimensions of mass x length / time2).
Energy is a force in motion (or its potential by virtue of relative position) with
units of force x mass (joule, with dimensions of mass x length2 / time2),
and an electrical unit of watt·seconds (power x time). Work is force through a distance,
with dimensions of mass x length2 / time2, which is the same...
 Here is the last engineering- and
science-themed crossword puzzle for June. These custom-made crosswords are done
weekly 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...
 My grandfather, Roland (my middle name) Somers,
on my mother's side was a residential (aka house) builder. He owned and operated
a small (2-3 employees) business in Mayo, Maryland in the middle of the last century.
Being his only grandson, I got what survived of his books like this
Audel's Handy Book of Practical Electricity, c1942, by Theo. Audel & Co.
Publishers. I also have a couple of his carpentry and hand tool books of the era. The
scanned page below is entitled, "List of Abbreviations to Be Used Radio Communication,"
as dictated by the International Radiotelegraphic Convention (IRC). Amateur radio
operators will recognize the list as being a collection of the familiar "Q" Signals,
although stated in sometimes archaic prose; e.g., QRN = "Are the atmospherics strong?"
and QSB = "Is my spark bad?...
 A
shortage of aluminum for manufacturing seems impossible given its abundance
in the form of bauxite - an ore of aluminum and iron - in many places of the world.
It is the third most abundant element in the Earth's crust after oxygen (20% of
the atmosphere) and silicon (sand)*, and is easy to mine because it is found close
to the surface. Today, aluminum is extracted and processed primarily in Australia
and - no surprise - China. The U.S., as with so many areas of production, has surrendered
its aluminum mining operations to offshore sources, thus exposing its critical
supply to the whims of trade deals. During the early days of World War II,
aluminum was being produced domestically, but enough foreign sources were being
used that the danger of shipping trade routes due to German U-boats...
 There was a time that selecting a
television antenna was as important to the quality of life as buying the right
smartphone is today. There were probably as many choices in antennas then as there
are phones now. You might think, especially if you are not an amateur or military
radio operator, that nobody worries about antennas anymore, but as I've written
before there is a slight resurgence in people installing the old fashioned multi-element
antennas for receiving local television and radio stations. The market's not huge,
but seems to be keeping companies like Channel Master in business. Incidentally,
in contrast to my aforementioned comment, dig the opening sentence of the article:
"Virtually no one in this day and age goes about discussing the reception quality
of his telephone..."
 Popular Electronics magazine used
to run a monthly electronics tutorial column entitled, "After
Class." Various guest authors wrote the articles. All you need to do is substitute
transistors for the tubes used in these fundamental oscillator circuits to bring
this article's content up to date. Or, maybe you are the owner of a vintage vacuum
tube radio and would like to learn a little about how things were done in the olden
days. Either way, as with so many aspects of electronic circuits, the basics haven't
changed much in the last 100 years. It's all still good. A list of all "After Class"
articles is at the bottom of the page.
 In August of 1940, issue No. 24 of the
Radio Trade Digest had a couple major historical announcements. The first
is "F.C.C. Authorizes Commercial F.M.," which assigned 40 UHF (42 - 50 MHz band)
commercial broadcast channels 5 non-commercial channels. Frequencies were changed
to 88 - 108 MHz in 1946. The second major announcement was that Philco (founded
in 1892 as Helios Electric Company, then changed to the Philadelphia
Storage Battery Company in 1906) had become a publically
traded company. It required private stock holders to convert and re-value their
holdings to make some of them available for public sale, which or course they voted
for. I don't know how IPOs worked back then, but my guess is they were not as dynamic...
 Your idea of a usable
portable radar probably does not include one that requires you to manually point
it at your surroundings and listen through a set of earphones for a tone's volume
and pitch to estimate distance to the target (or you can use the small analog meter
on the case. That was considered a technological breakthrough in 1971, and Kimball
Product Company's "Whistler" was the star. It only cost $595 ($3,743 in 2019 dollars)
for the capability. The trade name "Whistler" is very well known today, but I could
not find any information relating it to its namesake in this article. There is a
Kimball Electronics, but their About Us page is down at this time. Most likely,
though, it is The Whistler Group that is the progenitor of the radar unit mentioned
here. Today, they have an extensive line of portable radar units for marine, automotive,
aviation, and other applications...
 Most people today under 30 years old have
probably never seen the mechanics or electronics inside their many personal devices.
Everything is so miniaturized and optimized that if something does go wrong, there
is little chance of the owner repairing it. Instead, the phone, television, stereo,
microwave oven, whatever, gets thrown away and a relatively cheap (compared to paying
for a repair) replacement is purchased (or stolen). Besides, if the item was more
than two years old, it was on the verge of obsolescence anyway. Up until around
the early to mid 1980s you had a fair chance of being able to repair an electronic
circuit if trouble arose because at least with commercial products
printed circuit boards (PCBs) were usually 1- or 2-sided and the components
still had leads protruding from the sides of the packages...
 Summer begins this week in the northern hemisphere,
and winter begins south of the equator. Counterintuitive to northerners not familiar
with the geometric cause of seasons (axis tilt) is that the Earth is actually closest
to the sun in January than it is in July. Our orbital path is nearly circular, with
an eccentricity of just 0.0167. Anyway, I thought the onset of summer would be a
good time to post this installment of
Mac's Radio Service Shop entitled, "Summer Seminar." Typical of author John
Frye's techno-sagas, more than one theme runs through the story. It begins with
shop owner Mac admonishing technician Barney for throwing away a faulty selenium
rectifier when he knows there is an industry-wide shortage on supplies of the element
and the bad components should be submitted for recycling. Fretting over as common
an element...
 Since 2000, I have been creating custom
engineering- and science-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...
 According to Electronics
magazine editor Lewis Young in mid-1964, the industry was entering into a slump
in business opportunities. The boom times provided during the war years of WWII
and Korea had resulted in, according to Mr. Young, a lax attitude toward operational
strategy that led to wasteful spending and poor accountability for project results.
It wasn't just the defense contractors' fault because government bureaucrats - from
relatively low ranking military personnel to elected lawmakers - had (have) a habit
of making sudden changes to contract requirements. Maintaining the resources needed
to keep up with ever-evolving demands necessitated a lot of the excess. Fortunately,
the military-industrial complex, as President Dwight D. Eisenhower dubbed it,
was on the verge of being thrown another huge monetary bone - the Vietnam War. President
Kennedy was already pumping lots of equipment and manpower into it, and LBJ would
follow suit with vigor... |
