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Stratovision, October 1945 Radio-Craft - RF Cafe

Before comprehensive coaxial and optical cable or even microwave relay networks were available for commercial use, an experimental aircraft-based system was tested for broadcasting educational television and other messaging data. The "Stratovision" platform essentially provided a couple 20,000-foot-high antennas with a footprint covering hundreds of miles. This 1945 Radio-Craft magazine article entitled ,"Stratovision" was one of the earliest to report on plans to provide a coast-to-coast nationwide matrix of coverage as shown in the accompanying illustration. Two outfitted airplanes would be in the air within each region at all times to ensure redundancy and high quality service. Boeing B-29 Superfortress airplanes (the Enola Gay was a B-29) were used at least in part because they provided a human-friendly environment at high altitudes for long period of time...

U.S. Air Force Recruitment Advertisements in Saturday Evening Post - RF Cafe

Although the original purpose of this note was just to announce a couple post-WWI era U.S. Air Force recruitment posters I found in The Saturday Evening Post magazines back in the late 1940s, some info I found regarding the newest USAF logo might also interest you. There is a plethora of old Air Force posters available for viewing on the Internet, but I haven't seen these two, which are particularly directed toward flight officers and the newfangled jet aircraft of the future. Operational jet-powered fighter craft did not appear until the final year of World War II, although Germany did have their Messerschmitt Me 262. Except maybe for the C-130, you probably won't see any propeller-driven aircraft in today's USAF promotional material. If you have any cause to display the USAF's new (relatively) wings symbol, be sure to consult this entire section of regulations governing the proper...

Ford-Philco Radio, Model FT9, 6-Tube Auto-Radio Receiver Radio Service Data Sheet, April 1936 Radio-Craft - RF Cafe

This Radio Service Data Sheet covers the Ford-Philco radio model FT9, 6-tube auto-radio receiver. It appeared in a 1936 issue of Radio-Craft magazine. Most - if not all - electronics servicemen had subscriptions to these magazines because they were a ready source of not just these service sheets, but because of the extensive articles offering advice on servicing radios and televisions. In fact, many electronics manufacturers had a policy of supplying service data only to bona fide shops. Thumbnail photos at the left came from a Ford-Philco FT9 radio on eBay. A large list is included at the bottom of the page of similar documents from vintage receiver schematics, troubleshooting tips, and alignment procedures. They were originally published in magazines like this one, Radio and Television News, Radio News, etc. I scan and post them...

Practical Consideration and Application in a Multielement Quad, February 1967 QST - RFCafe

ABS and PVC plastic are the new bamboo for antenna construction. Before the ready and inexpensive availability of the former two insulative products, bamboo was the material of choice for lightweight insulative (at least when dry) support structures. Many of the antenna construction articles like this "Practical Consideration and Application in a Multielement Quad" article in this 1967 issue of QST magazine are typical of the time (and earlier) where bamboo was used to support wire radiator elements, and serve as spacers for ladder wire and matching-phasing networks. Author Fitz-Randolph provides a bit of theory behind the design and includes a table of elements lengths for 10, 15, and 20 meters (28, 21, and 14 MHz, respectively) operation. The tri-band quad antenna requires about 550 feet of wire! An interesting exercise for someone with extra time on his hands would be to plug the dimensions of some of these antennas into a programs like EZNEC and see how the software results compare to the articles' claims...

QuinStar Technology Engineer Captures Orion Nebula - RF Cafe

At QuinStar, we're about more than millimeter-wave technology. The people comprising QuinStar Technology pursue diverse and exciting outside interests. Our Chief Engineer, Jim Schellenberg, is a highly skilled amateur astronomical photographer. He captured this beautiful image of the Orion nebula using a specially modified Canon 6D. The camera responds to the H-alpha spectral line at 656 nm (from hydrogen gas), which is seen as red in the photo. The camera is mounted on an 11-inch telescope that tracks the object as the earth rotates. This image consists of nine one-minute exposures that are "stacked" to form the image you see. This is an excellent time of the year to view the Orion nebula. It can be seen with the naked eye...

How an Electronics Brain Works, June 1951 Radio-electronics - RF Cafe

It takes a while - and money - to accumulate issues of the vintage electronics magazines for posting articles here on RF Cafe. Often I can find groups for sale that comprise a full calendar year, but often they are groups of random months and years. That makes getting a complete series of articles like this one on "How an Electronic Brain Works" difficult. A lot of times installments appear every other month, so when a series has more than ten articles, it can run well over a year. For instance Part I of "How an Electronic Brain Works" appeared in the September 1950 issue of Radio-Electronics. The final chapter, Part XIII, appeared in October 1951. Throughout the series, authors Edmund C. Berkeley and Robert A. Jensen describe the workings of "Simon," their compact electronic computer - some even call it the first "desktop computer." Here is an article (with photos) about "Simon" in the November 1950 Scientific American magazine...

Homepage Archives for January 2022

Homepage Archives for January 2022 - RF Cafe Homepage Archives for January 2022. Items on the RF Cafe homepage come and go at a pretty fast rate. In order to facilitate fast page loading, I keep the size reasonable - under a megabyte (ebay, Amazon, NY Times, etc., are multiple megabytes). New items are added at the top of the content area, and within a few days they shift off the bottom. If you recall seeing something on the homepage but now it is gone, fret not because many years I have maintained Homepage Archives.

1952 National Company Advertisement

As the opening sentence indicates, National Company ran a very long series of advertisements in QST magazine that were in a format more reminiscent of a short essay than a company promotion. This installment for the December 1952 edition was number 224. Subjects ran the gamut from technical innovations from the company's research and development laboratory to social and political issues relevant to electronics technicians, hobbyists, students, and engineers. Being that it was a presidential election year in the U.S., National Company felt compelled to remind readers of their patriotic duty to vote. Although this was the December issue, it would reach readers' mailboxes prior to the election. Dwight D. Eisenhower ran against Adlai Stevenson. The latter won the South and the former won everything else. Note the thinly veiled criticism at the bottom about why amateur radio participation rate was down at the time...

Carl Kohler's Life & Times per Son, Christoverre

As mentioned in the past, one of the many great aspects of the Internet, and in particular having a website with its contents easily found on a search engine, is occasionally being contacted by people mentioned in one of the vintage magazine articles I have posted on RFCafe.com and AirplanesAndRockets.com, and/or by people related to someone mentioned. Readers of Popular Electronics magazine in the 1950's through 1970's (including me) looked forward to Carl Kohler's many humorous electronics-related stories and illustrations a few times each year. Carl's leading man was one of print media's first DIYers, and his wife suffered his often less than successful escapades in a sporting manner. A few days ago, none other than Christoverre Kohler, Mr. and Mrs. Carl and Sylvia Kohler's number two son (of four), contacted me to provide some background on his parents. Christoverre happened upon a couple of his father's articles on RF Cafe while doing a search. He was motivated to write in response to the story entitled, "I Married a Superheterodyne!," where I asked whether the Kohlers might have at one time lived in Syracuse, New York. It was due to a mention of General Electric's famous Electronics Park (which is no more). Christoverre set me straight on that matter, and provided some amazing additional information on his parents. His father's talents were not limited...

All Channel Antenna Corporation

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 that "outperform all present antennas." This particular "Super 60" model from All Channel Antenna Corporation further claims to outperform antennas that use a mechanical rotator (see my Alliance U-100 Tenna-Rotor) by virtue of its 9-position electronic phase switching...

Osgood Lens Advertisement

Finding information on the Osgood Lens, invented by James R. Cravath, is challenging. For as prominent as it was in magazines like The Saturday Evening Post in the late 1910s and 1920s, there is not even a Wikipedia entry for the lens type or the man according to my searches. Although not exactly the same as the Fresnel lenses used by lighthouses since the 18th century, the concept is basically the same. Of course the Osgood company was careful not to use the term Fresnel in their literature for potential patent infringement reasons. Some vehicles might have been fitted with them as a factory installed option, but they were also sold as add-on items. According to the literature the tiered stack of prism-shaped glass directed the headlight beam toward the road...

Mr. Math Analog Computer

$Mr. Math Analog Computer, June 1958 Radio-Electronics - RF Cafe$ Back in the early 1990s, while working for a fine Midwestern company that made automated utility meter reading (AMR) equipment, an older gentleman was hired as a contractor to do some design work. He was an instant hit with everyone not just because of his engineering prowess, but because of his stories of the mechanical and analog electronic computers he worked on for the U.S. Navy. After being commissioned as an ensign at the U.S. Naval Academy in Annapolis, Maryland, he spent time studying, researching, and designing massive radar-directed gun pointing systems for battleships. Just as contraptions like Babbage's difference engine was a marvel of contemporary engineering, so, too, were those fantastic shipboard amalgamations of gears, switches, vacuum tubes, rheostats, flywheels, cams, and bearings. Calculations of azimuths and elevations were made using sum, difference, integrating, and multiplication circuits built of discrete analog components and electronic valves...

Electronics-Themed Comics - July 1940 Radio News

Here are a few more electronics-themed comics from a 1940 issue of Radio News magazine. You can probably tell from the situations that people still considered "wireless," aka radio, to be a novel and wonderful - even mysterious - invention. Every type of situation from utility to obsession to fantasy was part of the experience. Two of the four comics from this set addresses amateur radio scenarios. Note the predilection predicted of viewers or the newfangled (at the time) television (or televisor). Little did the artist know how addictive such contraptions would be - first in the form of TV, then the form personal computer, and finally in the form of the present day video delivery medium of smartphones...

Engineering & Science Crossword Puzzle for January 19

As with my hundreds of previous engineering and science-themed crossword puzzles, this one for January 19, 2020, contains only clues and terms associated with engineering, science, physical, astronomy, mathematics, chemistry, etc., which I have built up over nearly two decades. Many new words and company names have been added that had not even been created when I started in the year 2002. 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, Russia, for reasons which, if you don't already know, might surprise you.

Make Extra Profits Changing Push-Button Radios to New Frequencies

The old pushbutton radio tuners were an ingenuous bit of electromechanical wizardry. For those too young to have experienced them, operation was simple - turn the radio tuning knob to your broadcast station, pull out the lever/button, and then push it all the way back in. Done. The next time you pushed that button, the mechanism would slew the dial indicator to that position, taking the tuning elements (usually just a variable capacitor) with it. For most modern electronic radios, you program the station button by pushing and holding it for a few seconds until a beep is heard. My father never quite got the hang of tuning the pushbutton radio in his old Rambler (vacuum tubes) or even his 1978 Chevy pickup truck (transistorized, but with mechanical tuner). He was never an early - or late for that matter - adopter of new technology, so it was not surprising. I am surprised, though, at the number of times I have had to show a Millennial type how to program his/her late model car radio...

On the Air with the Civil Air Patrol

Back in the 1970s while taking flying lessons, I used to enjoy watching the Civil Air Patrol run through its exercises at Lee Airport, in Edgewater, Maryland. For some reason, I never bothered to look into joining. I wish I had. A few years later while in Basic Training (BT) for the USAF at Lackland AFB, Texas, there were a couple guys in my squadron who had been long-time members of the CAP and guess what? They only had to spend the first two weeks in BT, just long enough to do all the paperwork processing, take a few of the classroom sessions, get shots, examinations, a head shave, and to have uniforms issued. Then, immediately before leaving for technical school, they got to sew a stripe onto their shirtsleeves as an Airman 1st Class. High school ROTC guys got to do the same thing. I don't know if the Air Force still has that policy; you might want to check it out if you're planning on joining...

Radar and LORAN

Mostly just old farts like me remember anything about LORAN (LOng RAnge Navigation). My familiarity with it came not from boat navigation, but from airplane navigation. Before LORAN became totally obsolete due to GPS (phased out in U.S. and Canada in 2010), the transmitter stations were commonly tuned in in order to obtain positional fixes via triangulation. Whilst taking flying lessons at Lee Airport, in Edgewater, Maryland, the ground instructor included it in the lessons, and even the FAA Private Pilot exams had a question or two on LORAN. The el cheapo Piper Colts that I flew were lucky to have a VOR (VHF omnidirectional range ) receiver in it, so I never actually used LORAN. They did have direction finders (DF), which could tune in, among other things, VHF television station channels...

Electro-Voice Stereo Speaker

While reading this vintage Electro-Voice hi-fi speaker promotion from a 1957 issue of Radio-Electronics magazine, the thought occurred to me that reconstituting that practice of offering products for sale in kit form could help solve at least three problems we have these days: high product costs, lack of knowledge and ability by most people for building material things and understanding how they work, and a shortage of workers willing to do factory jobs. With inflation in the 9% and up range, and government handouts removing the necessity of being a productive citizen by providing handouts, not only are formerly easily procured products difficult to obtain, but the prices are rising outrageously fast. Heathkit and other electronics products companies had a good idea that endured up through the 1980's, until manufacturing made a mass exodus from the U.S. to offshore venues in order to drive prices down. Americans lost good jobs that paid a decent wage while citizens of China and other countries did the work instead for compensation that barely paid for food, clothing, and shelter. Many were, and many still are, virtual slaves at the mercy of Communist dictatorships...