On December 31, 2015 at 11:00 UTC the Norwegian Loran C stations closed down transmissions. Below is a brief history of the Loran C system, the Berlevag station and what impact this station had on MW DX-ing in my area.
Loran C - A Navigation SystemThe following is an extract from Wikipedia articles.
Loran-C is a hyperbolic radio navigation system which allows a receiver to determine its position by listening to low frequency radio signals transmitted by fixed land-based radio beacons. The Loran system, beginning with LORAN, was inspired by the British GEE system, which entered service with the RAF Bomber Command in 1942. At the time it was designed for aircraft navigation, at a much higher frequency than today's 100 kHz. In 1958 the US Coast Guard adopted the system and over the years the system went from Loran-A to Loran-B to the current Loran-C.
Norway operated four Loran C stations; Berlevag and Bo i Vesterålen (Northern Norway), Stadt on the Norwegian west coast, and Jan Mayen, one of Norway's Arctic islands northeast of Iceland.
In 2009 the US Coast Guard announced that Loran-C was no longer needed for maritime navigation. US Loran-C stations were decomissioned in February 2010. The European Union had a different approach as one saw the potential of combining GPS, Gallileo and nine of the Loran-C stations into a single, integrated system (the Eurofix system).
However, Norway and France decided not to go along with this, and as a result, all four Loran-C stations in Norway closed on January 1.
The Berlevag Loran-C StationThe transmitter and guyed tower is located 4 km east of the town of Berlevag, and 14 km northwest of my DX location in Kongsfjord.
The power output was 250 kW on 100 kHz. It's placed on rocky soil, with a comprehensive ground radial system, comprising 180 radials with an average length of 250 meters. It had a diesel-fed generator for backup, and even a battery system enabling 45 minutes of operation.
|The Berlevag Loran C mast|
Impact on DX-ing
It was put into service in 1995, just as I was recovering from a rather long DX hiatus. I had purchased a JRC NRD-515 at the time, and the noise was horrendous. I could hear absolutely nothing on MW. I turned to long-time DX-er Stefan Wikander in Sweden (who had modified the NRD-515 for me), and asked what to do. "I'll make you a notch filter" he replied. The device centered on 100 kHz with 75 dB attenuation, and all of a sudden a large part of the MW band was DX-able again, albeit with lots of ticking noise on several frequencies especially below 1100 kHz. Many years later, Dallas Lankford from Ruston, LA refined the design with an additional 200 kHz notch filter combined with a high-pass filter, so the total attenuation on 100 kHz increased to 85 dB. Strangely enough there was no audible effect from the change. Anyway, these filters have been a vital part of every beverage antenna I have put up since.
I had my SDRs running at the time of the shutdown. Unfortunately conditions were downright awful at the time, but I did have two of my most common Alaska stations audible at the time (albeit with low signal levels), incidentally also on two of the most noisy frequencies.
So here's how it sounds when the Loran C station stops its noise on KBRW Barrow AK 680 and KFBX Fairbanks AK 970