Thursday, November 11, 2010

The story of CHU

The Story of the Canadian Chronohertz Station CHU

The Canadian chronohertz station CHU is well known in North America and beyond. The broadcasts from this time signal station can be heard quite clearly every day, and the reception of this station can be used quite readily as a guide to shortwave propagation conditions in North America. The story of station CHU goes way back into the earlier part of last century, back when radio broadcasting itself was very young.
The ornate Dominion Observatory was well known in Ottawa, the capital city of Canada. It was completed more than one hundred years ago, in the year 1905.
The usage of radio for the reception of time signals began in the Dominion Observatory in the year 1921, and during the following year an experimental station was launched under the callsign 3AF for occasional field usage. During the following year again, the regular broadcast of time signals was inaugurated over station CNRO also in Ottawa, one of the main radio broadcasting stations operated by the Canadian National Railways.
During that same year, 1923, the observatory launched its own radio station under the callsign 9CC (later VE9CC) for the experimental transmission of time signals on a regular basis. Station 9CC was licensed for operation on 275 metres, corresponding to 1090 kHz in what became the standard mediumwave band.
Four years later a new set of transmitters was licensed under the callsign VE9OB with daily transmissions on three shortwave channels, 3333 7353 & 14705 kHz. These channels were quite close to the amateur radio bands, thus ensuring a wide usage of the service by both amateur stations as well as professional shortwave broadcasting stations. Interestingly, the CHU time service on shortwave still occupies three channels which are rather close to the three original frequencies.
In 1938, the callsigns in use at the Dominion Observatory were regularized; the calls VE9OB & VE9CC were discarded and all transmitters on air were identified with the now familiar call CHU.
During the mid 1940s, plans were implemented for a new chronohertz radio station, no longer at the Dominion Observatory in Ottawa, but some miles out of town near Barrhaven at what was known as the Greenbank Road Shortwave Station. Greenbank was already in use at the time as a government communication station, and the first new transmitter for CHU was a war surplus unit rated at 300 watts. A wider service was subsequently inaugurated on January 1, 1951, with the three channels in use:- 3330 kHz @ 300 w, 7335 kHz @ 3 kW, 14670 kHz @ 300 watts

We note 30 years later, that a total of seven shortwave transmitters were in regular and standby usage for the CHU chronohertz service. That was in the year 1980, and these were:-
3330 kHz with two transmitters @ 3 kW
7335 kHz with two transmitters @ 10 kW & 5 kW
14670 kHz with two transmitters @ 3 kW
Spare 10 kW transmitter for emergency usage
Back a few years ago, station CHU came into prominent notice in the radio world, due to the fact that one of its regular channels, 7335 kHz, was located in the 40 metre amateur & broadcast band. Due to new international regulations, CHU would need to leave this frequency and move to another shortwave channel. There was some suggestion that the channel would be deleted entirely, or even perhaps that the entire station would even close down forever. However instead, a license was obtained for another channel, higher in frequency, and not within the amateur section of the band, and thus the station would remain in service.
An item in the World DX Club bulletin in England for February 2009 gives the interesting details of the change over from one channel to the next, from 7335 kHz to 7850 kHz. Currently, they operate only one transmitter and one antenna for this 40 metre band service.
Raymond Pelletier at station CHU in Canada states that the 40 metre band transmitter was shut down during the afternoon of December 31, 2008. A coil at the base of the antenna system was then changed, the transmitter was turned on again and re-tuned to the new channel 7850 kHz. Full power was then applied, and then the regular audio signal was applied, with its ticking sounds, and voice announcements in English & French.
International radio monitors who were listening to the change over on their radio receivers report that CHU left 7335 kHz at 2107 UTC on Wednesday afternoon December 31, 2008, and the transmitter was re-opened on 7850 kHz with an open carrier one hour and 20 minutes later at 2227 UTC. Eight minutes later again, the regular audio service was noted.
Currently, station CHU is on the air 24 hours daily on three channels:-
3330 kHz with 10 kW, the new 7850 kHz with 3 kW, 14670 kHz also with 3 kW

Interestingly, back in the year 2007, a call was made to establish an additional CHU service on shortwave for use in the western and northern areas of Canada where reception from Ottawa is unreliable and sporadic. However, up until this time, apparently nothing has been done in response to this need. It should be remembered also that a similar call has been made to establish a WWVB service on longwave for reliable coverage in the eastern areas of the United States.
Station CHU is a reliable verifier, and the Indianapolis Collection holds four different styles of QSL card dating from 1966 onwards.
(AWR Wavescan via Adrian Peterson NWS 89)