Emergency Broadcast System (partially lost Emergency Warning System; 1963-1997)
A video slide that was used to announce an EBS test on KEYC-TV in Mankato, Minnesota.
Status: Partially Lost
The Emergency Broadcast System (aka Emergency Action Notification System or EBS for short) was an emergency warning system used in the United States from 1963 in which replaced the CONELRAD up until 1997 when it was replaced by the Emergency Alert System. However, as the EBS was replaced by the EAS, recordings of EBS Tests & Warnings have become obscure and very hard to find.
EBS Stress Test (1963-1976)
During the early days of the EBS, stations would turn their transmitters on and off and transmit a 1000 Hz tone for 15 seconds and announce the test message. This became known as the EBS Stress Test by broadcasters due to the repeat nature of turning their transmitters on and off and the high chance for the equipment to malfunction. 
On August 27th, 2020, a YouTuber named Ellis Feaster uploaded a KDKA 1020AM Radio Air Check featuring an EBS Stress Test from December of 1969. This is the oldest known EBS Test recording to date. The rare recording can be heard below.
EBS Video Slides (1976-1997)
Beginning around 1976, each station was given a video card, in which various designs became available over the span of twenty years.
Around 100 EBS Video Slides (Mainly EBS Tests) from all different stations resurfaced online. It's unlikely that all EBS Video Slides will ever be recovered as there were hundreds of them made for each station throughout the United States.
List of Known EBS Video Slides
Note: Truly Lost EBS video slides are not listed since they are considered lost while ones that used to be on the internet but were unfortunately deleted are listed.
- Website that contains info on the EBS. Retrieved 23 Nov '17