Heath Company: Heathkit Advertisement
Heathkit's claim to fame was that it was
able to offer user-assembled kits of high quality electronic products at a price
lower than what equivalent factory assembled equivalents would cost. While that
is probably generally the case, it is difficult to gauge what the relative quality
really is. Some of the kits were easy to assemble for even people with little experience,
but a good portion of them required familiarity with soldering and how electronics
were put together. The instructions provided were very thorough, complete with photos
and drawings of how each step should look. In fact, according to a 1972 installment
of Mac's Service Shop entitled "Philosophy of a Kit Manufacturer," every Heathkit
kit instruction booklet goes through a rigorous cycle of writing, testing, and rewriting
before being released for production...
Building Your Own Audio Frequency Choke Coils
One very satisfying aspect of 'rolling your
own'
audio frequency coils (aka chokes, aka inductors), is how well the simple inductance
equations match measured end results. Unless you really manage to mangle the job,
if you use the right equation and are reasonably careful to observe wire size, spacing
(including insulation), and core diameter, you will be amazed at how close practice
matches theory. Although strictly speaking audio frequencies run from a few Hertz
up to maybe 15 kHz for people with really good hearing. My experience is that
similar success can be had even into the low MHz realm with just a little tuning
required. It's not until you get into the realm of self-resonance that everything
starts falling apart with basic equations...
Electronic Crossword Puzzle
This "Electronic
Crossword" appeared in the September 1958 issue of Radio & TV News magazine.
Its creator, John Gill, designed specialty theme crossword puzzles for many other
editions of Radio & TV News and Electronics World (see the big list at the bottom
of the page). He considered this crossword to be a "fooler" because he claims
to include many "unusual definitions and a number of obscure words which you will
have to work around if your vocabulary of 'exotic words' is rusty." It really doesn't
seem so difficult to me, and anyone used to working my custom RF Cafe Crosswords
will have no problem with it.
Transmission-Line Feed for Short-Wave Antennas
When someone with the first name of "True"
writes an article about transmission line feeds for short-wave antennas, you should
probably take note. This very topic has been covered in detail many times since
the use of impedance-matched transmission lines have been in use (more than a century),
but since there are always people new to the concept, it is good to keep introducing
the topic on a regular basis."Transmission-Line
Feed for Short-Wave Antennas" appeared in a 1932 issue of QST magazine.
Even in this era of prefabricated everything, it still often comes down to winding
coils and adjusting cable lengths to get optimal impedance matches between transceivers
and antennas.
Ward Para-Con Antenna
The word prefix "para" can mean "above and
beyond" or "resembling" or "abnormal or incorrect." Ward Products probably preferred
first two be inferred by potential customers when naming their
PARA-CON television antenna, although it actually is a shortening of "parabolic."
The "con" part is a shortening of "conical." After reading the text of this full-page
advertisement from a 1951 issue of Radio & Television News magazine, I'm inclined
to assign the third prefix meaning of "para" to it. Then, add in the "con" part
where "con" can take on either the noun form meaning of "disadvantage" or the verb
form definition of "to trick or defraud," and you get what this antenna truly represented
in terms of achieving superior performance. At best the PARA-CON exhibited the characteristics
of a phased pseudo-[bi]conical antenna. The allusion to a parabolic antenna...
Student's Radio Physics Course - Series & Parallel Circuits
Not everyone who visits websites like RF
Cafe is a seasoned electronics veteran. While I and most likely you, too, can do
series and parallel circuit analysis (and series/parallel for that matter, possibly
using Fourier or La Place transforms for reactive AC circuits) in our sleep,
many are recently getting into the wonderful world of electronics who are just coming
of age or have suddenly at a later point in life developed a passion for the craft.
Accordingly, this article from Radio News magazine provides yet another
tutorial on the fundamentals of series and parallel circuit analysis. Only resistors
and basic Ohms law are covered...
Comics with an Electronics Theme
Here are a couple more
tech-themed comics from a vintage electronics magazine (Popular Electronics).
The one from page 101 reminds me again about how different the world of retail sales
is today compared to just two short decades ago. Prior to the advent of online marketing
and sales, you either walked into a brick and mortar (a term rarely heard before
the Internet era) type store and walked out with your purchased product, or you
thumbed through a catalog and placed an order either by mail or telephone. Most
people opted to pay for a postage stamp rather than pay the long distance phone
charge (a term rarely heard today). Free overnight or 2-day shipping from many e-stores
makes online shopping nearly as instantaneous as walking into a store. People under
20 years old have never known much different, but some old-timers still find the
paradigm change strange. The way things are going...
The Ham Who Was President
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 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. Incidentally, the 1952 presidential election
was between Dwight D. Eisenhower and Adlai Stevenson. You might wonder how many
U.S. presidents were/are Amateur Radio operators. Answer...
Amateur Radio Crossword Puzzle for August 9th
August 9th's custom
Amateur
Radio crossword puzzle contains many words particular to Amateur Radio (labeled
with an asterisk *). Each week for two decades I have created a new technology-themed
crossword puzzle using only words (1,000s of them) 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, find
someone or something in the otherwise excluded list directly related to this puzzle's
technology theme, such as Hedy Lamarr or the Bikini Atoll, respectively. Avid cruciverbalists
amongst us...
Mac's Service Shop: A Typical Day in the Shop
Just as the title of this installment of
Mac's Service Shop, "A Typical Day in the Shop," suggests, the story is a
recollection of the kinds of scenarios that would found in an ordinary shift in
an electronics service business in the mid 1950's. Vacuum tubes were the norm of
the day, as were discrete leaded components and a rat's nest of wires running
from solder lug to solder lug. Printed circuit boards were beginning to appear
in commercial products, but mostly existed in specialty defense and aerospace
applications. You might wonder how many different ways could there be for simple
circuits like biasing and heater element lighting, but some pretty imaginative
variations made their way into radios, television, record players, and tape
decks, and often times that made a serviceman's life heck. Such was the case
here as über-owner-technician Mac admonishes sidekick Barney for not taking
time...
Know Your Levels
The old adage about a picture being worth
a thousand words is still true today, even in the Information Age in which we live.
A lot of people, especially those new to the field of electronics, struggle with
the
concept of decibels as applied to power and voltage (and to a lesser degree
current). A plethora of computer, browser, and phone app programs are available
to make individual, specific conversions, but what has been learned about the fundamental
relationship? A nomograph is still one of the best tools both for teaching and performing
conversions. This article that discusses properly matching impedances of amplification
stages includes a nice nomograph...
How Audions Were Built
If you have never read the story of
Lee de Forest's journey from initial experiments to finally achieving success
with his amplifying vacuum tube, the Audion, then you might want to take a few minutes
to look over this article. It was published in a 1947 issue of Radio-Craft
magazine as part of the 40th anniversary of the invention that changed the electronics
world. With so many other things which are nowadays very commonplace, we tend to
not think about or appreciate the ingenuity and effort that went into them. It is
one thing to make incremental improvements in an existing technology, but to conceive
of and created an entirely new realm of science is quite another. As with Albert
Einstein's relativity and Robert Goddard's liquid-fueled rockets, and the Wright
brothers' powered aeroplane...
Carl & Jerry: Extracurricular Education
This "Carl and Jerry" episode entitled "Extracurricular
Education" is a bit far-fetched compared to the typical storyline, but it does
illustrate how when you are desperate to get out a distress signal, a little technical
knowledge and having a knack for improvisation can save the day. Back then there
were probably a lot more people sitting around their radios or TVs who might have
heard the SOS message and actually know what it was. I am no Morse code master,
but anytime I hear the familiar di-di-dit dah-dah-dah di-di-dit (··· --- ···) cadence
in a movie or anywhere else, my attention tunes into it like a mother recognizes
her baby's cry in a noisy room. Interestingly, seat belts are mentioned in this
1963 issue of Popular Electronics magazine. Ford began installing them in 1955 as
an option...
RF Cafe Quiz #70: Analog & RF Filter Basics
This
Analog & RF
Filter Basics Quiz targets those of you who are relative newcomers to the world
of radio frequency (RF) electronics, but seasoned vets are welcome to give it a
go as well. It addresses frequency response and physical construction. Images were
obtained from Anatech Electronics documents entitled "Guideline for Choosing RF
and Microwave Products" and "Understanding Filter Types and Their Characteristics."
API Technologies' "RF & Microwave Filters," is also referenced...
Vintage College Engineering Labs
When I think back at the
engineering labs
from my days in school, I wonder how much things have really changed from then until
now. It is hard to believe that freshman and sophomore labs are not still consumed
with radial lead resistors, inductors, and capacitors, solderless breadboards, and
a variety of light bulbs, motors, transformers, relays, and rheostats. By the time
you move into the junior year, labs have gotten a bit more intense with microprocessor
controls (mine used an 8088 CPU with machine language programming for the serial
port), some high voltage apparati[sic], digital logic circuits, and a chance to
lay out/fabricate/populate a PCB. On-hand test equipment consists of 2nd or 3rd
generation oscilloscopes, signal generators, and power supplies. I did a search
for photos of labs from back in the early to mid 1900s to see if much had changed
from then until the time I was in college...
