The Radio Room Clock

Along with maps I think Hams are particularly intrigued by a nice clock.  Of course we always want a clock to put UTC time on and what better way to do that than with a clock that is both a time keeper and a conversation piece.  For those who are not familiar with the radio room clock or have seen it but were unaware of its significance.  The clock is easily recognisable with its green and red colour wedges at the quarter-hour points of the clock face.


The origin of the radio room clock goes back to the early 20th century.  Following the sinking of the Titanic, it was decided that coastal and marine traffic all use 500 kHz as the communications frequency for Morse code traffic.  The problem with this is that it made it a very busy frequency.  If a ship were to send a distress call on 500 kHz it could be lost in the congestion.  To remedy this problem, the Service Regulation stated that "Coastal stations engaged in the transmission of long radiograms shall suspend the transmission at the end of each period of 15 minutes, and remain silent for a period of three minutes before resuming the transmission."  This would allow distress calls to be heard.  As an aid to radio room operators, clocks were designed with a red wedge at 15 minutes past the hour and 45 minutes past the hour.  You can see this in old photographs but in Black & White, of course.  In later years a second set of wedges was added to the clocks at the top and bottom of the hour but these wedges were green in colour.  These represented silent periods twice per hour on the 2182 kHz for voice distress calls.

In the 1990s, with the decrease of the commercial use of Morse code traffic on 500 kHz, it was being monitored less and less until 1999 when it was discontinued.  Today there are many companies that sell replicas of the Radio Room clock and I got one for myself from Amazon.  It is a fine addition to any shack and will often be a conversation piece.

Cheers es 72/73 de Scott