Bruce Wilson wrote:
http://en.wikipedia.org/wiki/CONELRAD

In doing some research on Civil Defense I ran across the CONELRAD
stations. In Wikipedia's entry there is a statement that hams were
required in 1957 and later (presumably until 1963 at least) to check
that a major broadcast station was on the air.

Any old-timers remember this requirement? Was it regularly done by
working hams?

Yes it was a requirement and hams were *supposed* to monitor, but who
would really know if all hams did?

My dad had a home-brew Conelrad monitor that was in use at his ham
station whenever he was operating. It was a fixed frequency receiver,
tuned to WJR, a 50 kW, clear-channel (at the time) station located in
the Detroit area.

I was only 12 in '57 and two years away from getting my ham ticket, so
I'm not really sure of the technical details other than that it was
tuned to WJR (760 kHz) and operated a NE-2 neon bulb; if the WJR carrier
went away, the bulb went out. Even though it was home-brew, I don't know
if it was his own design or based on an article in the ham magazines of
the day.

One of the other posters quoted that hams had to monitor 640 or 1240
kHz--but that's not quite right. They just had to monitor a local BC
station...

From http://www.westgeorgia.org/conelrad/ :

Even Amateur Radio (ham) stations had to monitor a broadcast station
at all times, and to stop transmitting if there was a CONELRAD alert.

and from Wikipedia, http://en.wikipedia.org/wiki/CONELRAD:

Beginning in 1957, operating U.S. amateur radio stations were
required to verify at least once every 10 minutes that a normal
broadcast station was on the air. If not, the amateurs were required
to stop transmitting.

Please note they said "a *normal* broadcast station", not 640 or 1240 kc/s.