La Crosse Technology WT-3145U Manual

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La Crosse Technology WT-3145U Manual

Model WT-3145

Radio Controlled Analog Clock

Quick Setup Instructions

Welcome to the world of atomic timekeeping technology. We hope you will enjoy the convenience of never having to set your clock again and the confidence of knowing exactly what time it is.

Insert 1 new AA, LR6 1.5 volt ALKALINE battery in the analog clock battery compartment according to the polarity marked on the case, then 1 new battery AA, LR6 1.5 V into the digital clock.

Once the battery is installed, the clock will begin searching for a signal. For the initial setting, it is recommended to stand the clock in an upright position near a window. Within 3 - 10 minutes the clock will either receive the WWVB signal and set itself to the exact time (for the default Pacific Time Zone), or it will determine that the signal is not receivable at its current location and time of day. If the clock does not receive a radio signal soon after activated, the clock will start running from the 12:00 position and will continue to run. In this case, do not attempt to reset the hands manually even though the time displayed on the clock is incorrect. The clock is synchronizing to the WWVB signal and once the radio signal is decoded, the hands will automatically adjust to the correct time. The clock will fast-forward the hands to the 12 o’clock position immediately and search for WWVB at specific time until a signal is received. If the time is manually set, the clock will continue to periodically search for a signal and automatically reset the hands when the signal is received.

Press time zone button to select a time zone after the clock received the WWVB signal. If you are in the Pacific Time Zoneyou are ready to hang your clock.

If you are not in the Pacific Time Zone, select your time zone by press and holding for 5 second, one of the four time zone buttons PT-Pacific Time, MT-Mountain Time, CT-Central Time, ET-Eastern Time. If multiple buttons are pressed, the clock will set to the time zone selected last. If no time zone is selected the clock will default to Pacific Time. If you live in an area that does not recognize DST (Arizona) you must press the (unmarked) DST button for one second to deactivate your clock’s DST program.

For time zones outside of PT, MT, CT or ET you must manually set the time using the Manual Time set button on the back of the movement. (See instructions below). Please Note: WWVB time will over ride a manual setting.






















For a better understanding of how and why your clock works please continue reading.


Since the beginning of time, man has been fascinated with the measurement of time and has devised more accurate machines to trap and measure time. Today, time is precisely measured in the United States by the most accurate clock in North America, the Atomic Clock of the US National Institute of Standards and Technology, Time and Frequency Division in Boulder, Colorado. A team of atomic physicists continually measures every second of every day to an accuracy of ten billionths of a second per day. These physicists have created an international standard, measuring a second as 9,192,631,770 vibrations of a Cesium 133 atom in a vacuum. This atomic clock regulates the WWVB radio transmitter located in Fort Collins, Colorado, where the exact time signal is continuously broadcast throughout the United States at 60 kHz to take advantage of stable long wave radio paths found in that frequency range. Radio waves at these low frequencies use the earth and the ionosphere as a wave-guide and follow the curvature of the earth for long distances.

The built in antenna system will receive the WWVB signal anywhere in North America within 2000 miles of Fort Collins where long-wave radio reception is undisturbed. A microprocessor activates the receiver and processes the time signal from Fort Collins overnight.

Through the radio signals, La Crosse Technology atomic clocks always keep precise time. The changeover from standard time to daylight saving time, and vice versa, takes place automatically with the same precision.


To set up your clock simply install one new AA, LR6 ALKALINE battery. Due to the nature of long wave radio signals it is normally not possible to receive a signal during the day so it is best to install the battery late in the evening. After the clock sets itself to Pacific Time, select your time zone by pressing one of the four time zone buttons PT-Pacific Time, MT-Mountain Time, CT-Central Time, ET-Eastern Time. Your clock can only set itself to

one of the four time zones stated above. For time zones outside of PT, MT, CT or ET you must manually set the time using the Manual Time set button on the back of the movement. Please Note: WWVB time will over ride a manual setting.

The La Crosse Technology atomic clock is designed for indoor use. For indoor locations, select a location to place your radio controlled clock where it will be at least six feet away from a TV, computer, air conditioner or other household electrical appliances. The optimal location is near a window. Windows facing Colorado provide the best signal.


Do not submerge clock in water.

Extreme temperatures, vibration, and shock should be avoided to prevent damage to the clock.

The WWVB time signal will easily penetrate masonry and wood framed buildings. The WWVB signal will penetrate almost every residential building and most steel buildings if they have adequate windows. It is not possible, however, for the WWVB signal to penetrate most indoor shopping malls and rooms in the center of large office buildings that do not have windows. In buildings that WWVB cannot penetrate you may set the time using the manual time set button. When the clock receives the WWVB signal it will automatically set the hands to the exact time.

La Crosse Technology atomic clocks do not receive or process radio controlled time signals from Germany’s DCF 77, Japan’s J Ga AS, or England’s MSFs atomically regulated transmitters. La Crosse Technology atomic clocks can be manually set and used anywhere. Please Note: WWVB time will over ride a manual setting.

For more information on the NIST and radio controlled time, see


In some cases, the La Crosse Technology atomic clock may not receive the WWVB signal due to atmospheric disturbances or hard to reach locations such as inside shopping malls. In this case, please use the Manual Time Set button, located at the back of the clock to manually set the time. To do this:




1.Remove the battery and press the Manual set button 10 times.

2.Insert 1 new AA Alkaline battery.

3.Press and hold the Manual Set button until the second hand of the clock moves to the 12 position.

4.Release the Manual Set button and again press and hold the Manual Set button. The minute and hour hands will fast-forward while the button is held.

5.Keep holding the Manual Set button until the time is set as required.

6.Release the button. About 3 seconds later, the second hands will start to move and the clock is now running with manual time.

Note: When the clock displays manual time, it will continue to try to receive the WWVB signal at each of the even numbered hours: 0:00, 2:00, 4:00, 6:00 … 20:00 & 22:00.


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