1966 Adding Machine

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Fifty years ago, electronic calculators were things of science fiction, and even adding machines were expensive. The little circuit shown here filled a few of the gaps. It appeared in the September 1966 issue of the British Radio Constructor magazine.

According to the author, the device was built in response to a request by a friend who needed an adding machine to be used at motor car rallies in order to tally the number of miles covered.

It consisted of a telephone dial, a relay, and an electromagnetic counter, the type that increased by one every time a pulse was applied. The telephone dial had normally closed contacts, so the relay was necessary to convert to individual pulses. Also, the author noted that the telephone dial contacts probably couldn’t handle the current required by the counter.

The end result was that the counter increased by one for each pulse. So if you wanted to add 3+3, you would dial 3 twice, and the counter would count to 6.

Two-digit numbers could be accomplished by dialing zero for each 10. So to dial 34, you would dial zero three times, and then 4.

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1936 Four Tube Portable

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The picnickers shown here in the September 1936 issue of Popular Science are enjoying a radio program, thanks to the compact portable broadcast set shown here. It was light enough to take in a car or canoe, worked indoors or out, and could provide loudspeaker volume. The four-tube battery superheterodyne design was said to rival the performance of any all-electric set, but the article promised that anyone could build it.

The tube lineup of the set was 1A6, 1A4, 1B4, and 1F4, and was powered by five batteries: Two 45-volt B batteries provided 90 volts to some parts of the circuit, and 45 to others. Filaments were powered by two 1.5 volt dry cells, and a 4.5 volt C battery was also used. The batteries were packed snugly in the bottom of the case, behind the 6-1/2 inch permanent magnet speaker. The cabinet, covered in luggage canvas, was both attractive and durable.

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Science Fair Project: Atomic Frog Clock

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Here’s a picture of the time signal coming from the Eiffel Tower a century ago, as shown in the September 1916 issue of Wireless Age.

They were the results of experiments by one Dr. Lefeuvre, professor of physiology at Rennes University. The experiments were apparently carried out a few years prior, before the war, since they were also reported in the February 1913 issue of Popular Mechanics.

1913pmfroglegThe Eiffel Tower signals were received at a distance of 230 miles, and most remarkably, the mechanism for recording them was a frog’s leg, using the apparatus shown here.

Even though Prof. Lefeuvre conceded that there was no practical application to his system of “muscle writing,” it was regarded as a highly interesting laboratory experiment.

The sciatic nerve of the leg, cut below the knee, was spliced into the audio output of the receiver, with one end of the leg pinned securely to a base, and the other end connected to a lever. A pen recorded the impulses on the rotating drum.

Unfortunately, the “frog’s leg and its nerve do not retain their sensitivity very long,” precluding commercial application.

The experiment was, of course, an updated version of Luigi Galvani‘s 1780 experiment showing the frog legs could be made to twitch by application of static electricity.   Aspiring young mad scientists could probably develop an interesting science fair project along the same lines.  Instead of the Eiffel Tower time signals of a century ago, modern students in America could use the signals generated by WWV.  The now common “atomic clocks” rely on signals from sister station WWVB.  A bright student could quite easily construct a similarly accurate version, using the same user interface developed by Galvani over two centuries ago.  You might get some inspiration from this video:

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1966 One Transistor Regen

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One reason why simple transistor radio circuits proved challenging for early transistor experimenters was the low input impedance of bipolar junction transistors. This made it difficult to come up with an efficient circuit for a one-transistor radio.

But by 1966, the problem was largely solved by the appearance of the field effect transistor (FET), whose electrical characteristics were essentially identical to those of a triode vacuum tube. Fifty years ago this month, the September 1966 issue of Electronics Illustrated carried the plans for this one transistor regenerative receiver for the broadcast band.

The circuit used a Texas Instruments 2N3820, which sold for $3.75 plus shipping, and put out good headphone volume with a single transistor.

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Univ. of Minn. Electrical Engineering Bldg., 1926

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1926septradiobroadcastjanskyShown here ninety years ago is the Electrical Engineering Building at the University of Minnesota, from the September 1926 issue of Radio Broadcast magazine.

The magazine reported that the entire top floor of the building consisted of communication laboratories, principally devoted to radio instruction.  It was under the direction of Prof. C.M. Jansky, Jr., who believed that the program was the equal of any in the United States.

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WGU-20, “The Last Radio Station”

WGU-20 logo. Wikipedia image.

Forty years ago, the Spring-Summer 1976 issue of Communications World carried an interesting profile of station WGU-20, sometimes dubbed “the last radio station.”

The station was built at a cost of two million dollars in 1973, and operated with a power of 55 kW on 179 kHz with a 700 foot toploaded vertical antenna located at Chase Maryland. It was operated by the Defense Civil Preparedness Agency.

The station was designed to be the first in a network of longwave stations constituting the Decision Information Distribution System (DIDS) to warn the public of an enemy attack. An additional stations, operating on 167, 171, and 191 kHz were to blanket the continental United States with coverage, controlled by 61.15 kHz control stations at Ault, Colorado, and Cambridge, Kansas. In the event of an attack warning, civil defense authorities would send the alert to these control stations by landline or microwave, and the DIDS network would commence playing taped messages warning the public.

The station did QSL, and the magazine provided the mailing address for reception reports.

The network was never built, and the WGU-20 antenna was ultimately demolished in 2011. While it was operational, the station broadcast the time of day:

Good evening. This is WGU-20, a defense civil-preparedness agency station, serving the east central states with emergency information. Eastern Standard Time seventeen hours, twenty minutes, twenty seconds. Good evening. This is WGU-20, a defense civil-preparedness agency station, serving the east central states with emergency information. Eastern Standard Time seventeen hours, twenty minutes, thirty seconds. Good evening. …

The video below contains a recording of WGU-20, and was recorded at a later date after weather broadcasts were included in the broadcast:

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Rock Radio, American Samoa, 1944

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Shown here are Radio Technician First Class Kenneth D. McCoy of Salem, Oregon; Radioman First Class Stanley T. Dixon of San Francisco; and Radioman Third Class Charles H. Wilson of Steubenville, Ohio, the operators of 2-1/2 watt “Rock Radio,” located in 1944 in American Samoa. The picture and accompanying article appeared in the June 1944 issue of Radio News.

The station was cobbled together with scavenged parts including “tired tubes, broken bed springs, and stripped Jeep gears.” The station’s microphone consisted of the receiver of a Marine field telephone. The record player was an antiquated Victrola purchased for $3 from one of the natives.

Each night, the station came on the air, manned by whichever of the three was not on duty that night. It signed on with an almost worn out recording of the Star Spangled Banner, followed by a variety program of recordings chosen at random by the announcer. After a fifteen minute newscast, requests were taken. On Christmas Eve, the station recorded and rebroadcast the President’s message to the armed forces.

The station’s signal covered the entire island, and proved popular with the sailors and marines stationed on the island.

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1946 NPOTA Activation

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During the 2016 centennial of the National Park Service, the American Radio Relay League (ARRL) is conducting its National Parks On The Air (NPOTA) event.  Amateur Radio operators are setting up their stations in various units of the National Park Service (NPS) and making contact with other Amateurs around the world. Since the beginning of the year, the event has been extremely popular, with over 11,000 activations from 450 different different units of the NPS (with only 39 not yet activated), with over 640,000 individual two-way contacts.  As I’ve reported in other posts, I’ve made contact with 251 different parks, operated multiple times from six parks in Minnesota and Wisconsin, and plan to activate additional parks in the Midwest before the end of the year.

Even though this event is recent, operating portable from the National Parks is nothing new, as shown from the photograph above, which appeared seventy years ago this month in the September 1946 issue of Radio News.

Shown here are members of the Washington Radio Club operating Field Day 1946 from Shenandoah National Park in Virginia. Shown here are Dick Houston, W4QPW (apparently at the mike), along with Major Eric Ilott, G2JK, of the British Army (later VE3XE), and club secretary Barbara Houston. They are operating a 25 watt phone rig on 10 meters, with a Hallicrafters Sky Champion serving as the receiver. Power was supplied by a 300 watt gasoline generator.

Ilott, apparently at the left in the photo, served in the British and Canadian military until his retirement as a Lieutenant Colonel in 1974. He immigrated to Canada in 1947. During the war, he served as a listener for the British War Office, sending reports to Bletchley Park. Among his accomplishments after the war was bringing the first ever television signal to Kingston, Ontario, from an antenna atop a water tower. He died in 2015 at the age of 95.  (For another look at the early days of bringing distant TV signals to town, please see my earlier post on the first TV in Marathon, Ontario.)

1946 was the tenth running of the ARRL Field Day, an event in which hams set up stations at portable locations to make as many contacts as possible.

I previously wrote about the 1941 Field Day, in which the high scoring station had made 1112 contacts. That would be the last Field Day before the war, and the one shown here was the first postwar Field Day. According to the results in the February 1947 issue of QST, the top 1946 scorer made 809 contacts.

But the results article noted that it would be pointless to compare the 1946 results with those of prewar Field Days, since operating conditions as of June 1946 were quite different. In particular, hams had not yet regained access to the 160, 40, and 20 meter bands, which had been the workhorses for the prewar events. The 1946 Field Day was limited to 80 and 10 meters on HF, along with the 50, 144, and 420 MHz bands.

Shenandoah was not the only national park being activated in 1946. In addition, according to the results article, there were operations from Rocky Mountain National Park in Colorado and a battlefield national park in Virginia, as well as numerous other venues.

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Photo courtesy of N3KN.

While the Washington Radio Club took the honors of activating Shenandoah National Park in 1946, my own 2016 contact took place on February 8 on 20 meter phone.  Fortunately, the 20 meter band was returned to hams shortly after the war, as the contact on 10 or 80 meters in 1946 would have been considerably more challenging.  My contact was with Kay Craigie, N3KN, shown here.  In addition to being an avid NPOTA chaser, activator, and member of the NPOTA Facebook group, Kay is the immediate past president of the ARRL (a select group which included Herbert Hoover, Jr.).  She was at the helm of the ARRL when the NPOTA event was proposed and adopted.

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Du Mont Tubes, 1956

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Sixty years ago, the hapless TV repairman shown here was living the serviceman’s worst nightmare.  He had installed a cheap picture tube, and this consumer wasn’t happy about it.  The child shown here is now getting close to drawing Social Security, but probably still remembers the traumatic incident.

The moral of the story, according to this ad in the September 1956 issue of Radio Electronics, was that he should have used Du Mont tubes.

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1956: First Transistor Shortwave Converter

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Sixty years ago, the first transistorized shortwave converter showed up on the market, and it is shown here on the cover of Popular Electronics, September 1956.

The converter, Regency model ATC-1, used an SB-100 surface barrier transistor. It also included a 2N172 which did double duty, serving as a BFO for tuning SSB and CW signals. When the converter was switched to AM phone reception, that transistor served as a Q-multiplier.  It tuned the 80, 40, 20, 15, and 10 meter ham bands, and could be used with any AM radio.

While the converter was styled for mobile use, and included a mounting bracket for use in a vehicle, its small size and weight allowed it to be used with any AM radio tuned between 1200 and 1300 kHz.

The article noted that the power requirements were “almost unbelievably small,” and were provided for by three penlight batteries mounted on the back. According to the article, these would provide enough power to run the set for at least six months. They were mounted on the back, and could be replaced without opening the case.

In this cover photo, the converter is being held by Diane Pattou, a photographer and secretary with Popular Photography, a Ziff-Davis sister publication.

Some good pictures of the converter can be found at W8ZR’s site,  You can see the converter in operation at the video below.  The complete receiver shown here was assembled by a Regency employee, and used the converter along with a Regency transistor radio, and had an additional antenna tuner in the lower right corner.

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