OH3SHF Microwave Beacons in Tampere, Finland

OH3TR operates the OH3SHF microwave beacons. The 2.3, 3.4, 5.7, 10 and 24 GHz beacons are co-located with our 6 m and 70 cm FM speech repeater on the Hervanta water tower in KP11VK where we also have our VHF/UHF/microwave contest station.

The 2.3/3.4/5.7/10/24 GHz beacons are back on the air in April 2022 after some months of construction work on the water tower

Our 1.3 GHz beacon is licensed again for at least one year at a time now. It is hosted by the OH3NE club at their repeater site on the Tesoma water tower.

This picture of downtown Tampere at night, taken from the observation platform in Hervanta to the northwest where the Näsinneula observation tower with its OH3RNE FM repeaters is the distinguished landmark of Tampere, should give you an idea about the ideal location of the site. The horizon is far, far away, no matter which direction you look to. More pictures and a video clip can be found on the page profiling our VHF/UHF/SHF contest station.

The beacon antennas in Hervanta are mounted on a tubular mast on the sightseeing platform, about 210 m asl/55 m agl. The picture shows the original installation on our VHF/UHF/microwave contest station tower. The tip of the tower is 222 metres above sea level and 67 metres above ground level on the highest hill in town, quite near the university. The hardware is made by OH3LWP and OH3MCK with some help from the club members in installation and testing.

On the upper bands, the leading edge of the first dash of the letter "O" in the message is synchronised with a GPS receiver to the start of every minute. The 23 cm beacon is utilizing the PI4 mode by OZ2M in which the message starts with the PI4 FSK message on the minute.

Frequency accuracy of the beacons is better than 100Hz. The upper bands in Hervanta originally used a home brewed GPS locked 10 MHz reference by OH3MCK. The Philips GPS unit was later changed to a Rockwell one go tet rid of drift burst problems. Both sites now use a 10 MHz reference from a telecom grade Tekelec Temex GPS-disciplined timing unit.

"We are always exact, with other beacons your mileage may vary"

OH3SHF 1.3 GHz beacon on 1296.850 MHz

• Tesoma water tower KP11TM
• PI4 modulation
• 40 W transmitter power
• single slot Alford slot antenna 180 m asl
• about 8 dBi omnidirectional gain, horizontal polarisation
• ERP 50 W

OUT OF SERVICE FOR REPAIRS

The 23 cm beacon was shut down by Traficom 31st March 2020 because the radio amateurs in Finland lost the general access to the band. The beacon has now received an license extension to operate for one year at a time so far.

OH3SHF 2.3 GHz beacon on 2320.842 MHz

• Hervanta water tower KP11VK
• 50 W transmitter power
• single slot Alford slot antenna 210 m asl
• about 6 dBi omnidirectional gain, horizontal polarisation
• ERP 125 W

OH3SHF 3.4 GHz beacon on 3400.800 MHz

• Hervanta water tower KP11VK
• 20 W transmitter power
• single slot Alford slot antenna 210 m asl
• about 6 dBi omnidirectional gain, horizontal polarisation
• ERP 50 W

OH3SHF 5.7 GHz beacon on 5760.800 MHz

• Hervanta water tower KP11VK
• 8 W transmitter power
• 32 slot slotted waveguide antenna 210 m asl
• about 13 dBi omnidirectional gain, horizontal polarisation
• ERP 100 W

OH3SHF 10 GHz beacon on 10368.800 MHz

• Hervanta water tower KP11VK
• 4 W transmitter power
• 64 slot slotted waveguide antenna 210 m asl
• 15 dBi omnidirectional gain, horizontal polarisation
• ERP 80 W

OH3SHF 24 GHz beacon on 24048.800 MHz

• Hervanta water tower KP11VK
• About 0.5 W transmitter power
• 128 slot slotted waveguide antenna 210 m asl
• 15 to 18 dBi omnidirectional gain, horizontal polarisation
• Best radiation to east/west, smaller lobes to north/south
• ERP 30 W to the directions of maximum

All bands have individual messages starting on the minute:

Beacon message for 1.3 GHz:

PI4 message followed by OH3SHF KP11TM [long dash]

Beacon message for 2.3 GHz:

OH3SHF KP11VK 2320842 kHz [long dash]

Beacon message for 3.4 GHz:

OH3SHF KP11VK 2320842 kHz [long dash] (coming from the 2.3 GHz keyer)

Beacon message for 5.7 GHz

OH3SHF KP11VK 5760800 kHz [long dash]

Beacon message for 10 GHz

OH3SHF KP11VK 10368800 kHz [long dash]

Beacon message for 24 GHz

OH3SHF KP11VK 24048800 kHz [long dash]

The 1.3 GHz signal is multiplied by two from a VCO running at about 648 MHz locked to reference.

The 2.3 GHz signal is multiplied by four from a VCO running at about 580 MHz locked to reference.

The 3.4 GHz signal is multiplied by two from a VCO running at about 1.7 GHz locked to reference.

The 5.7 GHz signal is multiplied by eight from a VCO running at about 720 MHz locked to reference.

The 10 GHz signal is multiplied by six from a VCO running at about 1,7 GHz locked to reference.

The 24 GHz signal is multiplied by twelve from a VCO running at about 2 GHz locked to reference.

CW keying is done at VCO frequency.

The 5 and 10 GHz beacons were installed and activated in KP11VK on 15th June 2002 by OH3LWP and OH3MCK.

The 2.3 GHz band was installed and activated in KP11VK on 13th May 2003 by OH3LWP and the group. You can find some pictures of the installation here.

The 10 MHz GPS locked reference was added by OH3MCK in June 2003.

The beacon was QRT for a few weeks during the summer of 2003 due to damage from a lightning strike.

The 2.3 GHz band transmitter power was increased to 50W on 17th December 2003.

The 3.4 GHz band was installed and the 10 GHz TX power was increased to 4 W by OH3LWP in June 2005.

Some bands were again QRT for a few weeks during the summer of 2005 due to another lightning strike. This time more suppressors were added, also in the lines coming from the tower to the rack in the shack. The beacon was restored fully operational August 15th by OH3MCK and OH3LWP.

The 24 GHz beacon was installed by OH3LWP and OH3MCK July 12th, 2006. The GPS reference was also updated then.

All other beacons except 24 GHz have been off the air twice during September/October 2006. The problem was traced to a bad connection at the fuse holder in the +17 volt supply. The faulty holder was replaced October 9th.

The 1.3 GHz beacon was installed at another water tower in Tesoma (KP11TM) by OH3LWP, OH3HWX and OH3BK October 2nd, 2016.

The 2.3-24 GHz beacons were shut down in the end of October 2021 for some construction work on the water tower.

The 3.4-24 GHz beacons returned on the air early April 2022. The 2.3 GHz beacon will return in mid-May with a new PLL with much improved sideband noise.

Reception reports

In the early years we picked up some exceptional reports of the beacon via the DX Summit:

The full history of the reports is available on the DX Summit (press Refresh spots if you can't see the spots).

More pictures of the beacon and antennas

The pictures are here for download. Please feel free to use them, just mention the source.

You can find the list of all Finnish amateur radio beacons on the SRAL pages.

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Team OH3TR - Simply the Best