Thursday, July 15, 2010

Time Ticks Across the Pacific - The Story of Chronohertz Station WWVH

In our opening topic today, Time Ticks Across the Pacific, we present the story of another chronohertz station, this time the story of station WWVH in Hawaii. In actual reality, it is the story of two consecutive chronohertz stations, one on the island of Maui and the other on the island of Kauai.

We go back to November 22 in the year 1948, and it was then that the first of these two stations was inaugurated. The location was against the coastline near Kihei on the lower west side of the island of Maui. At the time, three transmitters were in use, all at 1 kW, and they radiated the time signal service on exactly 5 10 & 15 MHz. The antenna systems beamed the signals from this new Hawaiian station towards the west for the benefit of American interests in the Pacific.

Interestingly back at that era, the station in Hawaii was turned off twice each day, around 0700 & 1900 UTC, so that the staff at WWVH could check the transmissions from the mother station, WWV, which was located at Beltsville in Maryland at the time. In this way, the accuracy of the transmissions from WWVH could be checked against the infinitely accurate transmissions from WWV. The time distance between the two stations was just 27 mili-seconds.

In July 1964, voiced time announcements were introduced and these announcements conveyed the standard time in Hawaii itself.

Eight years after its inauguration, the power level at each of the three transmitters in the station was doubled, to an output of 2 kW each, still on the same three channels, 5 10 & 15 MHz. Ten years later again, another channel was taken into regular usage, this time 2.5 MHz with a power output of just 1 kW.

However, at about this time, it was becoming very evident that a new station would be required. The shoreline had been eroded by 75 ft and the ocean waters were encroaching upon the station. In fact, the ocean was now quite close to the main building, and also to the antenna tower in use for the 15 MHz transmissions. In addition, there was no air conditioning in the transmitter building and corrosion from the tropical salty air was taking its toll on the electronic equipment.

During the year 1968, Congress in Washington DC gave approval for the allocation of funding for a completely new chronohertz station in Hawaii.

This new station, with a whole set of new equipment, was installed into a new building located on a 30 acre property in the navy base at Barking Sands at Kokole Point, near Kekaha on the south western edge of the island of Kauai. A total of seven new transmitters were installed, all made by the AEL Company, and all rated at 10 kW, except for one at 2½ kW. The old station on Maui was progressively closed down and the new station on Kauai was progressively brought into operation in July 1971.

These new transmitters operated on the same standard frequencies, with 10 kW each on 5 10 & 15 MHz. The power output on the low frequency 2.5 MHz channel was just 2½ kW at the time, though this was increased to 5 kW shortly afterwards.

For each main transmitter, there was also a standby transmitter. In 1983, two of the AEL transmitters were removed and replaced by three Elcom-Bauer transmitters. On at least two occasions, hurricanes have damaged the WWVH shortwave station. In 1982, Hurricane Iwa cut off the reticulated power supply, and the station operated on emergency power for a whole week. In 1992, Hurricane Iniki caused considerable damage and the station was on the air for several days with just one transmitter, 5 MHz at half power.

Some ten years ago, new antenna systems were installed at WWVH and these are described as fibre glass whip antennas. Each antenna is encased in fibre glass and a copper wire runs the full length of the whip. In this way, corrosion from the salty air is minimized.

Currently, there is a total of eight active transmitters, primary & standby, at WWVH Hawaii. The main transmitters are powered at 10 kW and the standby units at 5 kW and they can be heard almost worldwide on four channels, 2.5 5 10 & 15 MHz.

The modulation level of the various broadcast services is different for each feature. The BCD time codes are inserted at 25% modulation, the steady tones at 50%, voice announcements at 75%, and the actual time pulses, the ticking of the clock, are at 100% level.

Back in the year 1977, it was announced that station WWVH received around 100 visitors each week and 200 reception reports. These days, they still receive many visitors, and they still receive a steady flow of reception reports.

Station WWVH at Kekaha in Hawaii can be heard at least some time of each day on at least one channel almost anywhere in the world. They readily verify all genuine reception reports with a three panel QSL card. You can identify the Hawaiian station by the voice of the announcer, a woman, speaking in English. If you have not yet verified each of their four channels, why not take the opportunity to do so?
(AWR Wavescan/NWS 732 via Adrian Peterson)