Tuesday, November 19, 2019

WWV 100th Anniversary: The Forgotten Callsigns

WWV Callsigns: KK2XEI South Boulder CO
The Central Radio Propagation Laboratory, as a division of NBS the National Bureau of Standards, was transferred from Washington DC into the new Radio Building on the newly acquired NBS campus in South Boulder Colorado in 1954.  The NBS property, made up of two tracts of land totaling 217 acres, is accessed by Rayleigh Road which runs off Highway 93.  A huge opening ceremony was staged at the new Radio Building on September 14, 1954 with 10,000 people present and President Dwight Eisenhower as the main speaker.

Two years after that grand opening on July 1, 1956, an experimental longwave chronohertz station on 60 kHz was inaugurated on the Boulder campus without ceremony under the experimental callsign KK2XEI.  This new KK2XEI was patterned after a similar longwave station MSF at Rugby in England which also utilized the same low frequency 60 kHz. 

The antenna system for KK2XEI was located a mile east of the Flatiron Mountain Ridge and it was supported by four wooden poles each 125 feet tall arranged in a square.  The feed line from the 2 kW transmitter ran up a similar wooden pole in the center of the square, with additional wires attached to the top of each corner pole.  This inefficient antenna system radiated just 2 watts, though even at this miniscule power level, the station was often heard at a considerable distance.

The radio frequency signal was unmodulated, except for an identification in International Morse Code every 20 minutes.  The station was on the air every working day from 1530 - 2000 UTC, running from mid morning to mid afternoon local time.

Four years later, the 60 kHz service was transferred from South Boulder and co-sited with another new NBS longwave station WWVL at Sunset Colorado, a small old mining town, half a dozen miles west of Boulder.  At the same time, the usage of the experimental callsign KK2XEI was dropped in favor of a new and regularized callsign, WWVB, with the B indicating Boulder.

WWV Callsigns: WWVL & WWVB Sunset, Fort Collins CO
Also in the late 1950s, NBS installed a mighty antenna across Four Mile Canyon for the experimental reception of longwave radio signals.  Four Mile Canyon is near the small old mining town known as Sunset, a dozen miles west of Boulder Colorado, and about four miles south east of Ward.

This massive antenna, which was anchored  to two mountain peaks on opposite sides of the canyon, stretched 3,400 ft (two thirds of a mile) across the wide valley.  The single wire antenna was a copper coated steel cable that weighed more than a ton and it was modified electrically for the transmission of experimental signals from two very low frequency transmitters, WWVB on 60 kHz and WWVL on 20 kHz.  The center fed upload cable was almost a thousand feet long, a little short of a quarter mile in height.

Station WWVL was inaugurated on April 5, 1960, with an 8 kW transmitter, though the radiated power was just 14 watts.  This station was initially on the air for six hours a day, though the duration of the broadcasts was subsequently extended to 24 hour continuous operation.  The last two letters of the callsign WWVL indicated very low frequency. 

This experimental station at Sunset Colorado was established to test the feasibility of worldwide longwave coverage from the one single location.  Reception of this WWVL was noted at times quite widely throughout the world, even as far as New Zealand.

During the early 1960s, a total of 30 sites were investigated in a search for a suitable location to re-establish the two longwave stations WWVL and WWVB, as well as all of the other WWV shortwave services from Greenbelt in Maryland.  The search was narrowed down to 7 possible sites in the Fort Collins area, and finally two parcels of land measuring a total of 380 acres were procured for this new station.

Work commenced on the new project near Fort Collins during July 1962, with the construction of a transmitter building and the installation of new electronic equipment.  The new WWVB service was inaugurated with 5 kW on 60 kHz on July 5, 1963, and the new WWVL service was inaugurated with 500 watts on 20 kHz one month later on August 6. 

Actually, the WWVB service at Sunset ended with a lightning strike on the antenna system shortly before the new station at Fort Collins was activated.  Some of the electronic equipment was destroyed in the resultant fire.

The original transmitters for WWVL and WWVB at Fort Collins were heavily modified ex military units, model number AN/FRT6, that were specifically re-engineered for low frequency time signal usage.  The two original antenna systems were best described as center-fed 8-wire flat-top diamonds, with an underground counterpoise.  The north antenna radiated the 20 kHz signal for WWVL, and the south tower radiated the 60 kHz signal for WWVB.

Originally, the WWVL signal was intended for worldwide reception, and for that intent to be realized, a much stronger signal would be required.  In fact, three years after WWVL was inaugurated at Fort Collins, the power level was increased to 2 kW.  However as time went by, NBS realized that they did not have the financial resources for the implementation of this 20 kHz project.

During the first six months in the year 1972, the signal from WWVL became frequently and deliberately intermittent until ultimately, at the end of the broadcast day on June 30 (1972), the WWVL transmitter was finally and permanently turned off.  WWVL was no more.

The 20 kHz WWVL antenna system, the north antenna, was then reworked for use on 60 kHz.  In this way, two WWVB transmitters were placed on the air simultaneously; both on the same channel 60 kHz.  Thus the two transmitters for station WWVB near Boulder now radiated from what had been its own antenna, the south antenna; and also from what had earlier been the WWVL antenna, the north antenna.
(AWR-Wavescan/NWS 558)