Technological and industrial history of 20th-century Canada the Keele Valley Landfill was operated by the City of Toronto from 1983 until 2002, when it was closed because it was full. Chlorofluorocarbons (CFCs), the gas propellants used in aerosol spray cans, became a target for environmental concern in the 1970s and 1980s when research demonstrated that they had a harmful effect on the ozone layer in the atmosphere. The international Montreal Protocol of 1989 banned the use of these substances and they were subsequently replaced with volatile hydrocarbons. The problem with choice to reuse is still not available. There are many products that don't need to be recycled
QSK operation (full break-in) QSK operation must ensure that their radio equipment includes the hardware capability for radio frequency antenna switching that operates rapidly enough to allow listening between signals at the appropriate Morse code sending speeds with appropriate lifetimes and reliability. QSK operation (full break-in) "Turning over" a communications channel is the change in communications protocol transmission status that occurs when a transmitting station releases transmitting control of a communications channel thus turning it over to allow another station to transmit. QSK or full break-in operation is one of several techniques and protocols for turning over control of a Morse code radiotelegraph communications