Skip to main content
U.S. flag

An official website of the United States government

Dot gov

The .gov means it’s official.
Federal government websites often end in .gov or .mil. Before sharing sensitive information, make sure you’re on a federal government site.

Https

The site is secure.
The https:// ensures that you are connecting to the official website and that any information you provide is encrypted and transmitted securely.

WWVH Photo Gallery

The Station's Surroundings

After serving the Pacific area for 23 years from the Island of Maui, Hawaii, Radio Station WWVH was relocated to the western edge of the Island of Kauai, Hawaii in 1971. The facility is located near Kekaha at Kokole Point. Around the clock, continuous broadcast services from Hawaii supplement those from WWV in Fort Collins, Colorado, by providing coverage in the Pacific Basin.

Entrance

WWVH entrance
Station entrance to WWVH in Barking Sands, Kauai.

 

Sunset

sunset from WWVH full size
View from WWVH, Niihau Island on left horizon.

Station house

WWVH station house full size
WWVH in Barking Sands, Kauai. In the foreground is the weather instrument tower, in background, standby 2.5 MHz monopole.

Old Station

WWVH old station full size
WWVH in Kihei, Maui 1948 to 1971. Antennas left to right: 10.0 MHz, 5.0 MHz, Reception, 15.0 MHz, and 2.5 MHz. Buildings left to right: Office, transmitter, generator & shop.

Clocks & Antennas

Several cesium atomic clocks provide the precise timing information broadcast by WWVH, these signals are amplified by transmitters (below) and broadcast from several antennas. Three atomic frequency standards at WWVH provide optimum timekeeping ability. These "atomic clocks" are kept in as close agreement as possible with the UTC(NIST) time scale located in Boulder, Colorado.

Clocks

a bank of electronics at WWVH
Credit: D. Okayama/NIST
Time and Frequency Rack: Digital recorders, Multi-channel chart recorder, Clock A, Clock B, Clock C, & Error detection/auto-switching system.

15 MHz antenna

WWVH 15 MHz antenna full-size
15 MHz antenna array. Two half-wave vertical dipoles separated by a quarter-wave length and driven 90 degrees out of phase.

 

Sunset

WWVH antennas
Antennas left to right: Standby 2 broadband and 2.5 MHz dipole.

Antenna field

WWVH antenna field full-size
Left to right: 20.0 MHz array (abandoned), 15.0 MHz array, 10.0 MHz array, 2.5 MHz dipole, Standby 1 (SB1) broadband, and Standby 2 (SB2) broadband.

Transmitters

These transmitters amplify the time signal that is sent to the antennas.

Left view

WWVH transmitter full-size
Transmitters from left to right: Primary 5.0 MHz (10kW), Standby 5.0 MHz (5kW), and Standby 15.0 MHz (5kW).

Center view

WWVH transmitter full-size
Transmitters from left to right: Standby 15.0 MHz (5kW), Primary 10.0 MHz (10kW), and Primary 15.0 MHz (10kW)Console panels left to right: oscope and multi-channel recorder; modulation, carrier and master control for transmitters; and station status, RF exiters and audio amplifiers.

 

Right view

WWVH transmitter full-size
Transmitters from left to right: Primary 2.5 MHz (5kW), Standby 10.0 MHz (5kW) and Standby 2.5 MHz (5kW).

10,000 Watt

WWVH transmitter full-size
WWVH Typical Interior of a 10000 Watt Class C Plate Modulated Transmitter Top left: Final tuning circuit Top right: PA and modulator tubes Bottom Left: High voltage power supply, control panel Bottom Right: Modulator transformer, screen power and choke.

At WWVH, only one clock is "on the air" at any time. The other two permit clock comparison and emergency or standby service. Satellite synchronization methods are used to keep WWVH clocks "in step" with NIST/Boulder standards.

A time code generator allows recorded voices and special announcements to be programmed automatically into the broadcast format. This information provides modulation through a synthesizer for the four standard broadcast frequencies. A female voice announces WWVH's time, thus allowing distinction from WWV's male voice. The RF signals are amplified through high power transmitters and fed to the antenna systems. The antennas are modified half-wave dipole phased arrays with the exception of the 2.5 MHz and standby monopoles.

Created April 28, 2015, Updated December 6, 2016