Monday, September 12, 2016

Mount Loran: A Beverage Antenna Experiment

Berlevag's Loran C site, a 25- minute drive from our Kongsfjord DX location (14 km as the crow flies), was a serious challenge for MW DX here. Transmissions closed on December 31, 2015, and DX has been a lot easier since then. However, we wondered if  the Loran C site could pay back in some way, so we started to investigate the possibilities to put up a temporary beverage antenna there. The plateau (not really a mountain) is almost flat terrain on rocky soil near the ocean, and with some OK spots for placing ground sticks. An added benefit is that it's accessible by car - a very important issue when you need to carry 1000 meters of antenna, and heavy batteries. The starting point is around 150 meters from a dirt road.

After a few inspections we found the ideal place for a 1000-metre beverage at 305 degrees, aiming at the US east coast. After receiving the necessary permission to use the facility, we started planning.

We wanted to do unattended wideband recordings but with internet connection so we could monitor and listen online. We opted for an Intel NUC PC, which can run off a 12VDC supply such as a battery. The NUC also has USB 3.0 outputs so it can power a Perseus and a small 4G modem. And of course a 2.5" hard drive. The battery was 80Ah and had been tested to run continously for 58 hours, although indoor and without the 4G modem connected.

It turned out that the Loran C station had an unexpected last twist up its sleeve, namely the strobe light on top of the 214-meter mast. The noise was at first very demotivating, and at one point we decided to abandon the site. Luckily we changed our minds. The pulsating noise does ruin DX on many frequencies. But with changing between USB og LSB and adjusting  filter widths the benefit outweighs the cost.

At the time of testing, we also compared this 1000-metre, 305-degreees beverage with the Kongsfjord 275-metre, 310-degrees beverage. Apart from the strobe light noise, the noise floor is very low and signals are exceptionally clean. We also noted that on most frequencies, interference from European and Middle East stations was significantly lower. Signals from North America arrived earlier, disappeared later and were generally stronger than on the Kongsfjord beverage.

This rather brief test very early in the season was to gain experience with the logistics, testing the equipment and finding out if we should proceed during the KONG33 DX-pedition in late October. There is no doubt we will do this again. Maybe we find a way to reduce if not eliminate the strobe light noise.

What will happen to the Loran C site in a longer perspective is anyone's guess. This and the other Norwegian Loran C sites were scheduled for dismantling, but apparently a UK company is now negotiating on bringing the network back to use. If so, we need to reinstall our Loran C notch filters. If not, the tower and other equipment will likely be put down, and we may have a noise-free location for the future!
The 214 meter Loran C tower

305 degrees, 1000 meters. Loran C station on the left side

Loran C while operative, October 2015

Box with Intel NUC, Perseus, HDD and 80Ah battery

Terminating point. Bjarne (left) and Ole Forr. Pennsylvania below the horizon.

Starting point. OJ Sagdahl (in front), Ole Forr.

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