DVOR Trouble

Last year we encountered a DVOR problem in which the Nearfield position RF level is too low that caused an alarm on our two monitors. It shutdowns both system of DVOR. We bypassed the two monitors and check the actual RF level by using a DVOR portable receiver. All the actual reading of data in aerial is the same as per recorded normally in our logbook. We concluded that the equipment is operating normally and the problem is in the monitor dipole section.Through analysis and at the same time reading the equipment manual we decided to troubleshoot at the dipole section of the DVOR. We loosened and tightened back the transmission cable and clean all connectors for possible contamination of rust. The problem still existed, and we then checked the 3dB attenuator if its the caused of the problem. We found available attenuator and changed the existing one and still the problem is just the same. After all the possibility we decided to focused on antenna itself. We brought down the antenna of monitor and we found out that it had made by ants as its habitat and all its holes were contaminated with dirt's. We disassembled the antenna and by used of pressure washer we cleaned thoroughly all the contamination.After cleaning we assembled again the antenna and brought up and all data on RF nearfield level goes back again into normal state.

        figure of Antenna  monitor dipole