There's been an apparent gap in the APRS network coverage around Karkkila, and we already several years ago acquired a ex-police VHF network basestation location from Alhovuori. Every time I have driven pass the tower I've looked up and confirmed the antennas are still there, so there still has been hope to put the digipeater up :)
Finally last week I came up with a solution of a 'temporary' digipeater OH2LAK-2 to put up to the tower. Well, it ended up being quite good looking setup, so it might not be temporary, only the callsign might. It might be easier to apply a real digipeater callsign for the long run.
The digipeater setup consists of a MDR VHF radio modem which is very famous in Finland for APRS which it's rewritten firmware HaMDR, the rack chassis is a controller chassis of another VHF base-station from Elektro-Arola. It featured a nice AC to 12V power supply, power switch and fuse panel, so it was a great choice for the digi.
From old habit I equip all the things I build with a Cisco-style console port, so a RJ-45 jack. I have an endless supply of the blue RJ45-D9 cables, and it can be considered as some sort of a world standard. Below the console port jack there's a configuration switch, which enables the configuration mode during power-on for the HaMDR radio modem.
We drove up to the Alhovuori site with Marko OH2BUF with clear plans to leave few hours after with a working digipeater running at the site. Alhovuori is a ski center, but during the summer season there are variety of activites around, which this time means horses. The very rough road up to the site which is next to the ski slopes, passed a grassland for horses which was fenced around. Luckily the fence could be opened to get through :)
I knew that the very last POVI basestation would be waiting for us at the site. I felt quite nostalgic dismantling it from the chassis as it was truly the last of its kind, still installed and capable of operating and hooked to antennas. (I've listened quite much of the fellow policemen talking through this thing in the past!)
Unfortunately the DC power feed to the base station was removed, so we could not check it's functionality any more :(
Finally last week I came up with a solution of a 'temporary' digipeater OH2LAK-2 to put up to the tower. Well, it ended up being quite good looking setup, so it might not be temporary, only the callsign might. It might be easier to apply a real digipeater callsign for the long run.
The digipeater setup consists of a MDR VHF radio modem which is very famous in Finland for APRS which it's rewritten firmware HaMDR, the rack chassis is a controller chassis of another VHF base-station from Elektro-Arola. It featured a nice AC to 12V power supply, power switch and fuse panel, so it was a great choice for the digi.
Unfortunately the DC power feed to the base station was removed, so we could not check it's functionality any more :(
The digipeater sits nice on the same TELENOKIA rack cabinet, we also found by accident some spare front plates and filled the front of the rack with them, so the installation was even cleaner.
The antennas of the digipeater are the very topmost antennas, three dipoles on each side of the tower to create an omnidirectional radioation pattern. The antennas are sturdy Aerial Oy dipoles with a reflector grill, model AV1523-3
The computer model of the expected coverage of the station using Radio Mobile Online matches quite well the results derived out by the APRS.fi system with the data of the actual traffic relayed through the particular station. The digipeater itself is configured to relay packets only from a distance of 50km or less to avoid overlapping with other digipeaters. The tropo conditions experienced lately have made the OH2LAK-2 digipeater to be heard in Sweden though, so it is most probably a working setup by all means.
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