[AMRadio] OT. Retuning for Conelrad?

[Karl Zuk]

Ancient technology here.

I can't ever remember when the Conelrad system was tested on the air. 

Long ago, I worked at WFAS 1230 in White Plains NY.
We had a system for Conelrad that simply switched the frequency of our transmissions from 1230 to 1240 by exchanging crystals in the crystal oven. No retuning of antenna systems needed. The station had a single self-supporting tower and could operate at one kilowatt.

The theory behind the system was that - in time of war - that all broadcasts - from a select few stations - would revert to 640 and 1240 kcs to confuse the enemy who would be trying to use broadcast stations to geolocate and triangulate. Theoretically, the enemy wouldn't know where the remaining Conelrad broadcasts were coming from.

Similar in thought was the EBS - Emergency Broadcast System. This system was periodically tested long before the obnoxious quacky duck alert tones were used. We had a fixed receiver set on WCBS 880 - our strongest local clear channel. A broadcasted tone would open a squelch so you could hear the emergency broadcast. Again, in theory, these broadcasts could over-ride local broadcast audio. 

EBS affiliates had to log when these broadcasted tests happened. Missing a logging could result in an FCC fine if your station was inspected and your log did not match all the previously sent tests. 

All participating EBS stations had yellow or orange envelopes posted in the operator's position. If an actual alert was sent, you were to open the secret envelope and see if the printed password matched the word the mother station was sending for authentication. The word would change for each calendar date. 

The envelopes were never ever supposed to be opened. The station was to destroy them when they were periodically updated with a new envelope. Again, I never saw thus authentication system ever used. Did anyone else ever had to open the secret envelope? 

All of this reminds me of an old comedy routine:

"We will bomb them at high noon! They will think it's lunch!"

Karl Zuk  N2KZ  Katonah, NY USA






On May 11, 2024, at 11:04 PM, Leland Bahr <w5drc at eastex.net> wrote:

You got it right, Brad.

Lee, w0vt

On 5/11/2024 9:36 PM, B Farrell wrote:
> Nick,
> 
> I believe stations not assigned those frequencies for standard broadcast
> transmissions had dedicated receivers in their control booths tuned to
> those frequencies and relied on those 640/1240 stations. If I recall
> correctly, if the system was activated the stations not on 640 or 1240
> would retransmit the 640 and 1240 signals broadcasting civil defense
> messages. Hopefully, someone with more knowledge will reply.
> 
> Brad K4RT
> 
> On Sat, May 11, 2024 at 9:07 PM Nick England <navy.radio at gmail.com> wrote:
> 
>> Did commercial AM stations switch crystals and retune transmitters for
>> Conelrad at 640 or 1240kc or did the system depend on stations already
>> operating on those frequencies? If stations retuned, did they also have to
>> retune antennas?
>> 
>> Nick England K4NYW
>> www.navy-radio.com
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