Tampereen teekkarien radiokerho
P.O. BOX 692, 33014
Tampereen yliopisto
Tampere, Finland
QRV 145,375 MHz
& 434,950 (-2,0) MHz
Tel. +358 40 854 7379

APRS nodes

Team OH3TR operates two APRS™ nodes, OH3RDR and OH3RBR. OH3RDR is a high-performance dual band RX-IGate, while OH3RBR is the backup IGate of Tampere region.


IGate node OH3RDR is co-located with the OH3SHF microwave beacons and OH3RTR repeaters at the Hervanta water tower. We've tried to run it as a digipeater too, but the idea had to be dropped soon because it seemed digipeat pretty much everything from Southern and Western Finland during even slightly improved propagation conditions. Since then it has been running as a RX-IGate on both 2 m and 70 cm bands. Two meter frequency is the normal IARU R1 144,800 MHz, but on UHF we have to use the secondary APRS frequency of 432,500 MHz. Using the primary frequency 433,800 MHz is not possible due to serious interference from the Finnish 433,050-434,790 MHz ISM band.

Downtown Tampere
by Night
A picture of downtown Tampere by night, taken from the observation platfrom of the water tower, gives you an idea about the location of the site.

Live statistics of the node are available. It is also possible to monitor traffic on OH3RDR by connecting to it with telnet.

telnet radioclub.ele.tut.fi 443


VHF antennaAerial AV1431 5 dBd stacked dipole pointing east at 57 m AGL / 212 m AGL
VHF radioComarco MDR150, 5 watts, includes TNC
UHF antenna  Sharing OH3RTR 70 cm RX antenna, Kathrein K 75 16 2 21, 5 dBd omni at 67 m agl / 222 m asl
UHF radioMobira Talkman MD59, TX disabled to avoid damage at the 70 cm repeater RX unit. KAM TNC.
Computer1 U 933 MHz x86 PC, running Debian GNU/Linux and aprsg


OH3RBR works as backup IGate on 144,800 MHz. It relays local APRS-IS-only traffic to RF, if the local main IGate OH3RBE is not working for some reason. The backup functionality is implemented by adding a three-second delay into APRS-IS to RF gating. If the main IGate does not gate a packet while OH3RBR is holding it, RBR transmits the packet after the delay.

Team OH3TR - Simply the Best

© OH3TR 1996- (disclaimer)
Last updated: Saturday, 05-Nov-2011 20:24:06 EET