The "Evaluacion Solar" Laboratory of the Technical University Federico Santa Maria (UTFSM) in Valparaiso exists since 1957. Some types of sun following systems using instruments for different types of solar measurements were created during the mentioned period in this Laboratory. A solar tracking unit INTRA was recently installed in the UTFSM. It is considered a modern measuring and registering system for actual measuring of radiation in digital form, easier to store and to process. The action of the sun tracker is autonomous, which makes it a flexible tool to support direct radiation measurements. A special device was designed and constructed to support the measuring instruments. Three Eppley pyrheliometers were mounted on the unit and connected with an automatic registering system. An additional UV measuring sensor will be mounted soon. The realized measurements were compared with the results obtained manually from a K&Z pyrheliometer. The difference between both types of pyrheliometers is very small, which is a good precondition for using the INTRA sun tracker for precise measurements in the future. (C) 2003 Elsevier Ltd. All rights reserved.