We have been having a similar problem here in Toronto on 224.86. The frequency has been in use for years but recently we have been finding carriers on the output. Many have suggested we put a PL on VE3RPT but that is avoiding the issue. One member has observed that they seem strongest near traffic lights, as if there is some unshielded micro inside them. Has anybody else observed this phenomenon? If so, maybe we can compare to see if it is always the same make of traffic light controller.
Unfortunately I don't have a mitre on 220! 73 Nigel, ve3id Director TFMCS (VE3RPT/VE3TFM/VE3TWR/VE3SIX)
