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...