Today marks the 100th anniversary of floods in San Antonio, Texas, that killed 215 and caused $19 million in damage.
On September 7, a hurricane made landfall near Tampico, Mexico. It lost cyclonic characteristics the same day, but the storm remnants were forced northward. It stalled over central Texas, causing the devastating flooding in San Antonio and other areas. Some stations reported as much as 40 inches of rain in a 24 hour period.
We’ve previously written about the NEAR system, which was a system envisioned to alert the American public to a nuclear attack. It relied upon a 240 Hz signal superimposed upon the power lines. This signal was picked up by an ingenious electromechanical receiver in the home, and sounded a loud buzzer in the event of an alert. We previously described how the receiver worked, and the August 1960 issue of Popular Electronics, from which the pictures above were taken, explains the equally simple method used to transmit the signal. In the schematic at right, at the utility substation, to send the alert, switch S1 is opened. The rectifier sends a flow of DC
pulses through the transformer secondaries, generating a signal at the fourth harmonic of the power line frequency. This signal averaged about 2-3 volts, meaning it would not interfere with regular power transmission.
On that October day, the alarm originated at a radar station in the Arctic, from which it was relayed to NORAD headquarters in Colorado Springs, CO. An officer there pushed the button to activate the NEAR system, resulting in the alarm being sounded almost immediately in Charlotte, MI.
That morning, seniors at the high school, the Charlotte Class of 1961, had inflated weather balloons and distributed them around town. When the devices buzzed in each home, homeowners were to release the balloon on a tether. Back at the courthouse, the students were in the tower of the courthouse counting balloons.
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This year marks the 70th anniversary of the Great Flood of 1951 along the Kansas and Missouri Rivers. With 17 deaths and almost a billion dollars in damage, the flood was the nations then-costliest natural disaster.
The photo above shows downtown North Topeka, Kansas, from the July 30, 1951, issue of Life magazine.
According to the November 1951 issue of QST, much of the Amateur Radio response to the flood focused around the U.S. Naval Reserve. Station K0NRZ at the Naval Reserve Training Center in Topeka maintained a continuous watch on local emergency frequency 29.5 MHz from July 11 to 15. On the 15th, a long-haul net was established on 7042 kHz and handled over 1000 messages through July 20.
One ham reportedly furnished handie-talkies (3885 kHz) which were used for communication between Army/Air Force trucks and Coast Guard boats engaged in sandbagging the levees.
The QST October issue also reported that the station K0NAB at the Naval Air Station in Olathe, KS, handled radio traffic for Western Union, whose lines were out.
This young woman shown above in Popular Mechanics 70 years ago this month, June 1951, is using her portable radio to pull in some entertainment at the beach. But she also realizes that in a civil defense emergency, the set might have a vital role to play if the bombs started falling.
The problem, of course, is that you need batteries for the radio, and many sets had oddball shapes and sizes, some of which might not be available in the runup to an emergency. Therefore, the magazine gives some pointers on substituting what’s available. Even though the batteries might not fit in the case, with a little thought, it was a relatively easy matter to power the radio for emergency information.
Shown here, on the cover of the May 1951 issue of QST is ARRL’s then-National Emergency Coordinator, George Hart, W1NJM, operating a portable 6 meter civil defense portable station designed by Ed Tilton, W1HDQ and described in the magazine.
Tilton’s article described the design goals of the set. He noted that in the past, emergency gear almost always meant “rigs with handles,” namely equipment that could be operated on a 6 volt battery or small AC supply. While such rigs were the backbone of WERS during World War II and would continue to occupy a prominent place, the “present emergency” brought a new need, namely, communications for the radiological survey team. Those teams required on-the-spot communications with a transmitter-receiver that could go with an operator on foot, and not tied to a car battery or other power supply.
The choice of bands to be used presented some problems. A simple modulated oscillator (such as the one described in another magazine the same month), would eliminate the expense of crystals, but they were really practical only on the 220 MHz band, since the civil defense frequencies assigned on 2 meters were two narrow a range for such a transmitter. On 6 or 10 meters, however, crystal oscillators were more cost effective, and between the two, 6 meters allowed a shorter antenna. Therefore, the choice boiled down to 6 meters, if crystal control was desired, or 220 MHz, if it was not. The circuit shown here was a crystal-controlled transmitter-receiver for six meters.
The transmitter used a 3A5 dual triode. The first half was a 25 MHz oscillator using 8.4 MHz crystals on their third overtone, or 25 MHz crystals. The second half of the tube served as a doubler. The set could also be used on 10 meters with different crystals, and using the second half of the tube as an amplifier rather than doubler. A 3Q4 was used for modulator. The superregenerative receiver employed a 957 acorn tube detector, with another 3Q4 serving as audio amplifier.
Since the author couldn’t find another suitable carrying strap for the rig, a piece of 300 ohm twin lead was pressed into service.
Seventy years ago this month, the May 1951 issue of Radio News carried the plans for this 220 MHz transceiver designed for civil defense use. The band was chosen because of it was authorized for use by holders of the newly minted Technician license. With many younger hams being drafted, it was thought that opening up opportunities for Technician class hams would be a way to bring in the operators that were urgently needed for civilian defense operations.
The main design parameter for the set was to provide reliable communications over a 5 mile range. This would be sufficient to cover a small town, or, in the case of a larger city, one police precinct, upon which civil defense operations were often based. Lower bands could be used for inter-city communications, freeing up units such as this for use in local emergencies.
The heart of the circuit was a 955 acorn tube, with more common miniature tubes (6J6, 6J5, and 6V6) rounding up the circuit. The 955 operated as a superregenerative transceiver. The tuned circuit used off the shelf components, but the capacitor required some modification to cover the entire band. If a frequency meter were not available, the magazine noted that in a TV with a 21 MHz IF, the set’s local oscillator would radiate on 225 MHz, allowing calibration of the transceiver. An additional hint in areas with a channel 13 TV signal would be that if the TV station were audible, this meant that the transceiver was tuned too low.
The author reported good signals over a 17-mile path with the set, meaning that for its intended use of 5 miles, the two watt set would likely perform well.
Seventy years ago, this gentleman was pulling in a program on the standard broadcast band with headphones, but in the following months, he would be able to listen to the shortwaves with loudspeaker volume. He is shown here listening to the first iteration of a progressive receiver featured in the May 1951 issue of Popular Mechanics. In coming months, additions would be made to the set to allow shortwave reception and loudspeaker operation.
The set was battery powered, and the magazine pointed out that there were a number of good reasons for putting together a battery set. The most important reason was having a set capable of operation independent of the power lines for civil defense purposes. The circuit was also simpler and saved having to deal with baffling power supply troubles.
This version of the set used a 1U4 tube as regenerative detector followed by a 3V4 audio amplifier. An indoor antenna and ground could be used for local statioms, but an outdoor antenna would be best for long distances. “With a battery-operated emergency receiver of this description, you are not cut off from outside news and vital civil-defense information should local power sources fail. Most of us do not realize how important this could be.” You would, of course, need to keep fresh batteries on hand. The circuit called for flashlight batteries for the filament, and a 45 volt battery supplying the B+.
Seventy years ago this month, the cover of the March 1951 issue of Popular Science featured this artwork by artist Denver Gillen (who made the first drawings of Rudolph the Red Nosed Reindeer, and later, numerous covers for Outdoor Life) showing “what an A-Bomb blast may do to your home,” but with an inset of a family safely hunkered down in their family foxhole.
The cover entreats the buyer to save the issue, since it contains a special section on emergency preparedness written by Michael Amrine, formerly of the Atomic Energy Commission.
The magazine’s editors noted that much of the literature regarding civil defense was “tragic nonsense–aspirin for cancer. Even the official booklets say mainly, ‘Keep calm, keep covered, and follow directions.” But it goes on to say that official directions might not be forthcoming, since there did not exist civil defense organizations comparable with the problem. Instead, the magazine advocated “planning and plain hard work” by individual homeowners, and the magazine contained advice on how to do that. “The hard truth is that the most you can expect from civil defense will be control and rescue work after a bombing. The most effective preparation for atomic attack will be family by family, house by house.”
The article first noted what not to do, and pointed out that steps such as blacking out the house, taping windows, or even buying a Geiger counter were of very minimal utility. It noted that, as in Hiroshima and Nagasaki, radiation was not going to be the big killer. Instead, it would be the familiar forces of heat and blast, and the article gave pointers on preparing a refuge room to protect against them. The author asked readers to “imagine that your house is in a cyclone or hurricane belt, and next door to a gas tank” and plan accordingly. The most important principles in planning a refuge room were making sure there were at least two exits, keeping out from under heavy furniture or appliances, and preferably being in a corner of the cellar with the least windows or exposure. The importance of using a corner is illustrated by the drawing at left.
After a spot was located, ideas such as shuttering windows and making use of a heavy table or workbench were outlined.
The article included a number of frequently asked questions, including “what should I tell the children?” The answer was simple: the truth. They should be instructed where to go in a raid and how to hit the deck. You shouldn’t scare them, but don’t make it a game, either.
For homes without a basement, the author suggested placing earth or logs against an outside wall, with a sturdy table inside.
The list of recommended supplies included the usual suspects such as canned food and battery operated lights. Under the category of “valuables,” the recommendation included an extra pair of glasses and a lockbox for valuable papers. Rounding out that category was money (in small bills), on the assumption that, as in the last war, the economy would be in full operation.
The list included a wind-up clock and maps of the city and county. The battery operated radio made its usual appearance on the list. The article noted that utilities would probably be out, although some, especially the gas lines, might continue to function for a time. Since battery operated radios were still quite rare (but not unheard of) in 1951, the article noted that a car radio would also work.
The article did note that it was dealing with just the Hiroshima-style A-bomb, and not the H-bomb. It notes that the H-bomb was then still just a theoretical possibility, but that if perfected, it would wreak the same level of damage over a still larger area.
One of the great challenges of civil defense planners was alerting the public to an imminent nuclear attack. Sirens could be effective outdoors, but it was unlikely that people indoors would be able to hear them. One possible solution is discussed in the March 1961 issue of Radio-Electronics: NEAR, the National Emergency Alarm Repeater.
Three methods had been considered: telephone lines, power lines, and radio. The technical challenges for using the telephone network for simultaneously alerting the entire population were too difficult to overcome, and not everyone had a phone. Radio was a possibility, but radios were turned off many hours of the day, and especially at night. NEAR took advantage of the power grid. With only a few hundred repeater stations, a 240 Hz signal of about a volt could be superimposed on the line, and the receiver shown here was a clever electromechanical method of picking up that signal and sounding the alarm.
The home NEAR until shown here would be plugged in and forgotten by the homeowner until such time as there was an attack. It included a resonant circuit consisting of a 0.55 uF capacitor and 1 henry coil, with a tuned frequency of 240 Hz. To avoid false alarms, there was a time delay in the form of a 1 RPM motor. If the incoming signal were less than 10 seconds long, then the motor would simply reset and continue listening for a signal. But after 10 seconds, the motor would trip a clapper which used the outside of the device’s case as a sounder. The unit would emit a loud annoying noise which would alert the homeowner to the missiles that were incoming.
Fifty years ago today, the Emergency Broadcast System (EBS) sent out a warning that the nation was under attack. Thankfully, it turns out it wasn’t. A test was scheduled for that Saturday morning, but an operator at the Cheyenne Mountain complex put in the wrong tape. Instead of the tape announcing that it was only a test, he ran the tape for a real attack. It contained the code word “hatefulness” to authenticate the message.
At radio stations around the country, DJ’s ripped open the envelope next to the teletype machine containing the authenticating code. And sure enough, that was the correct code word for that day. Stations were supposed to cease normal operations and begin broadcasting information about the attack. But that information was never forthcoming.
Since a test had been scheduled, many stations suspected that there was an error, but it wasn’t confirmed officially for 40 minutes. The most famous recording from that day comes from WOWO in Ft. Wayne, Indiana, which you can hear in this video, where announcer Bob Sievers interrupted the Partridge Family with the news:
You can also listen to the event from WCCO Minneapolis at RadioTapes.com.
