Shown here 70 years ago, in the March 1956 issue of Popular Electronics, is CHU station staffer J.P. Henderson making an adjustment to one of the  timing devices in use by the station at the Dominion Observatory in Ottawa.  The voice announcements were recorded on the soundtrack of 35 mm film, and a system of cams was used to start the correct announcement of station ID, hour, and minute.

The magazine noted that during the summer months, the observatory was open to the public for astronomical viewing on Saturday nights.  During each session, there was also an open house at one of the observatory’s divisions, meaning that radio fans had a couple of opportunities each year to visit the radio station and see it in action.

Since January 1, 1955, the station had been on the air giving the exact time on its then frequencies of 3330, 7335, and 14,670 kHz.  Many North American hams, like me, undoubtedly used the 7335 signal as a means of making sure their 40 meter receiver was in calibration.  These days, the 40 meter frequency has moved to 7.85 MHz, but the other two frequencies remain in operation.