Picture the following scenario, in a slightly grainy black and white for added effect. It's the 1950's; a ham is sitting at his station, having a CW QSO. He's wearing a suit and tie, before him is a Hammarlund receiver, a Johnson Viking transmitter, and a homebrew modulator. On the wall are QSL cards and his Honorable Discharge Certificate. On the table is a collection of QST magazines, along with some curious pamphlets, with titles such as "Protect Them--Join Civil Defense", "America Calling--Take Your Place in Civil Defense", "It CAN Happen Here", "Know the Signals", and even a comic book featuring a character called "Bert the Turtle". While the Vibroplex clicks away, another radio sits in the background, quietly spitting out atmospheric noise. It's an AM Broadcast receiver, one of those 5 tube AC/DC models produced by the millions. This unit--an Arvin in an Art Deco plastic cabinet--is tuned to one of two triangular markings on the dial. Suddenly, the silence is shattered by a piercing 1000 cycle tone. The ham looks up, rips off his headphones, and listens to a message. He jumps from the chair, runs to the door and yells to his wife "Grab the kids and go down to the Fallout Shelter. The CONELRAD alarm just went off".
CONELRAD, which stood for "Control of Electromagnetic Radiations", had its embryonic start in December, 1951 when President Harry Truman signed an Executive Order directing the FCC to set up a security system for all civilian radio services. Throughout 1952, CONELRAD was developed and tested and, by early 1953, it was ready. The purpose of CONELRAD was to relay Civil Defense information to the public without allowing enemy aircraft to use our radio signals as a beacon for their direction finding equipment. In the event of an emergency, all FM, TV and most AM stations would proceed with the following alarm sequence:
>>CURRENT PROGRAMMING DISCONTINUED
>>5 SECONDS-CARRIER OFF THE AIR
>>5 SECONDS-UNMODULATED CARRIER
>>5 SECONDS-CARRIER OFF THE AIR
>>15 SECONDS-1000 CYCLE MODULATED CARRIER
>>1 MINUTE MAXIMUM-INITIAL CONELRAD MESSAGE
>>CARRIER OFF THE AIR FOR THE DURATION OF THE ALERT
The remaining AM stations would shift to either 640 or 1240 kc and simultaneously broadcast a more detailed emergency message. The stations would constantly turn their carriers on and off. For example, Station A, operating on 640 kc, would broadcast the emergency message for 15 seconds and suddenly cut its carrier. The public would then hear Station B, also on 640 kc, with the same message. When Station B went silent, Station C would appear and, after a few seconds, Station A would be back on the air. This "cluster pattern" would continue until the emergency message had been broadcast. The same activity would be happening on 1240 kc. No call signs or other ID would be given. In this way, the FCC and the Office of Civil Defense hoped to confuse enemy aircraft trying to use AM radio stations as a homing beacon.
The ARRL and the FCC realized that amateur stations might also serve as a beacon. Therefore, from the beginning, amateurs were urged to keep watch on 640 or 1240 kc, and to kill their transmitters when the alarm was given.
With the importance of CONELRAD in the early 1950's, it's surprising that amateurs were not required to monitor for the CONELRAD alarm. This was rectified on January 2, 1957 when the FCC amended Part 12 of the Rules and Regulations to require the following:
>>All operators of stations in the Amateur Radio Service will be responsible for the reception of the CONELRAD RADIO ALERT by monitoring 640 or 1240 kc.
>>During a CONELRAD RADIO ALERT, all operators of Amateur Radio
Stations will CEASE COMMUNICATIONS IMMEDIATELY.
>>Stations operating under the Radio Amateur Civil Emergency Service (RACES), and other stations specifically authorized, would be allowed to remain on the air under the following restrictions:
a) No transmission shall be made unless it is of extreme emergency, affecting the National Safety, or the Safety of life and property;
b) Transmissions shall be as short as possible;
c) No station identification or location shall be given. Tactical calls will be utilized if necessary.
d) The radio station carrier shall be discontinued during periods of no message transmission.
>>Amateur Stations shall not allowed back on the air until the CONELRAD RADIO ALL CLEAR MESSAGE is transmitted.
With the requirement of continuous Broadcast Band monitoring, homebrew projects, kits, and commercial products began to appear to help the Amateur keep in compliance with Part 12.190. While some Amateurs simply used an AM radio, others bought or built specific CONELRAD receivers. Heathkit had the CA-1 CONELRAD Alarm; Morrow Radio had the CM-1 CONELRAD Monitor; and the Walter Ashe Radio Co. had the model CA "Conelarm". Radio Shack's first transistor radio, which sold for a mere $29.95 in 1958 dollars, was advertised as "perfect for monitoring CONELRAD".
When Class D CB Radio was authorized in September, 1958, the rules specified that CB'ers also had to monitor CONELRAD. In the event of an emergency, all Citizen Band operators had to leave the air--there was no RACES provision for them.
By the early 1960's, the possibility of long range enemy bombers homing in on our radio signals was becoming remote. Instead, Intercontinental Ballistic Missiles were the new threat. They didn't require our broadcast signals as Beacons. CONELRAD was becoming obsolete. Thus, in the autumn of 1962, CONELRAD was replaced by the Emergency Broadcast System. Ironically, CONELRAD disappeared right around the time it might have been needed the most--the Cuban Missile Crisis.
As the 1960's wore on, the Cold War gradually dissipated, and the Specter of imminent enemy attack disappeared. Today, only the faded "Fallout Shelter" signs, and those triangular markings on old AM radios remain to remind us of CONELRAD and the Cold War. As I write this, I can hear a Springfield Mass station on 640 kHz, while a hetrodyne of Class 4 stations co-mingles on 1240. And yet, what is that I hear, faintly in the background?? A 1000 cycle tone??
Copyright 1996, 2001, 2005 by William Continelli, W2XOY
All rights reserved.
These columns were originally written for the Schenectady Museum Amateur Radio Club.