A trailer tongue extension assembly that includes a tubular trailer tongue, a removable extension, a first electrical connector disposed within the trailer tongue and a second electrical connector disposed within the removable extension. The microwaves cause heating of the hydrocarbons in order to upgrade the hydrocarbons. If is not true, HPX is compared with threshold value T2. The waveguide material is adapted to carry at least a reference beam and a measurement beam. A system for effecting the method is also disclosed. The sheet conveyor roller pairs are arranged so that at least one of the rollers of each pair is independently pressed against the other with a force corresponding to the type of the sheet.