Akademisk Radioklubb

LA1K / LA1ARK / LA1UKA

The annual “spring trip to Vassfjellet leads to discovery of broken beacon” blogpost

This weekend we finally had the opportunity to go to our beacon site at Vassfjellet, as the snow had thawed at last (or so we thought). Our plans were to install the newly constructed 6 m beacon, LA2SIX, and assess what had happened to the site over the winter.

We have not been able to hear LA2VHF/4, our 4 m beacon, for a while. This was disconcerting, as it might mean that the antenna which we planned to co-use for LA2SIX had suffered some damage during the winter.

100 m from the summit, we encountered the first and only pile of snow on the road. Unfortunately this was enough to foil our plans, and the rest of the trip had to be made on foot.

ARK’s beacon cabin.

Once we reached the top, we were surprised to find that the vertical VHF antenna was missing. Luckily, some passerby’s had placed the antenna in a secure location nearby, so we were able to retrieve it.

Apart from thorough carbonization of base and antenna contacts (probably due to beacon transmissions during the fault scenario) the antenna seemed relatively intact. The failure seems to have happened due to our lack of maintenance on the set screws which keep the antenna from unscrewing itself in heavy vibraton/wind. Nothing bad to say about the antenna, though, as it lasted 7 years without maintenance in conditions that have proven themselves extremely harsh.

We attempted to clean up the antenna as best we could, and re-installed it on the base. Our efforts were in vain, however, as the antenna reported more than 10:1 SWR across the band.

Antenna analyzer result is a textbook example of bad SWR.

Unfortunately we need to announce that LA2VHF/4 will be temporarily offline while we perform repairs to the beacon and antenna. We have brought LA2VHF/4 back to the lab bench for a thorough examination, since transmitting into an open load for an extended period of time is bound to have caused some damage to the finals.

We have set plans in motion to be able to fix both beacons, hopefully in time to get the most out of this summer’s sporadic E season. We hope to return soon with an update on this matter.

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