Due to the problem buses being loca

Due to the problem buses being located in Melbourne I have only been able to carry out some preliminary testing using items that I have available to me here in the Perth workshop, my findings are below: Items tested:New “improved” headlamp supplied by factoryHeadlamp supplied from parts (item without improved circuitry) Test rig:Portable battery pack (power supply)Audiobus radioSpeakerAerial and 3m extension lead. Method:Head lamps were set up on bench, and radio positioned approximately the same distance as it would usually be when in vehicle and aerial connected and positioned approximately 3m away from headlamps, radio was tuned to various frequencies and the DRL in each head lamp activated individually and noted level of interference coming through speaker. Findings:Both headlamps have a noticeable level of interference, the interference is at its strongest when the radio is tuned between 89MHz and 95Mhz, the “improved” headlamps where found to have louder interference than the item supplied by parts, also worthy of note is that there is also interference present (but quieter) when the park lamp circuit is powered, most likely due to the same invertor/style invertor being used. The frequency band where the interference is most prevalent is the range where the majority of the radio stations in the area are broadcasting on. It should also be noted that the radio did not pick up interference from either of the headlamps on the AM Band (535-1060kHz). Conclusion:Although it is certain the DRL and park lamps in the headlamps is a cause of interference, the frequencies effected in bench testing do not match up with the level of interference experienced in the vehicle, thus more testing needs to be carried out to further determine the source.