Marked by a red band on the dial, the two 3-minute silent periods (no signals transmitted) which must be observed by all radio stations beginning at 15 and 45 minutes past each hour, for the purpose of listening for any distress calls sent by radiotelegraph (International Morse Code) at a radio frequency of 500 kilohertz.

Marked by a green hand on the dial are again two 3-minute silent periods (no calls transmitted) which must be observed by all radio stations beginning at each hour and half hour, for the purpose of listening for any distress calls sent by radiotelephone (Voice) at a radio frequency of 2182 kilohertz.

The 4 second marks in red around the outside edge of the minute track over which the sweep-second hand passes, enables the radio operator to accurately transmit the 4 second alarm signal provided by the International Telecommunications Convention and the International Conference of Safety of Life at Sea (SOLAS).

The dial is arranged with the conventional 12 hour numerals, plus a secondary row of smaller hour numerals from 13 to 00, so that direct reading of Greenwich Mean Time is clearly and easily obtained for logging as required.

The clock has two hour hands. One of them, the black one, is geared directly to the movement and driven by it. This "main" hour hand is set on Greenwich Mean Time and thus the clock is always running on and correctly indicating Greenwich Mean Time. The other hour hand is white and is not geared directly to the movement, but is held to and driven by the "main" hour hand by a positive friction device, and thus is manually movable to any point on the dial to indicate local zone time.

The Radio Room Clock is available in mechanical or quartz movements. The clock is also available in either a 6" molded phenolic material hinge case or a 6" solid brass case.

Clock features:

Availability: This item has been discontinued.