An RF welder, and a method of operation thereof, is disclosed that has circuitry that automatically affects system impedance so that, throughout the welding or embossing cycle, a generator is capable of delivering the same power to a die and fabric, and cabling is capable of dissipating a load that is less than a preselected amount. A predetermined strain has been applied to each film. Alternatively the fluid could be fuel, water or urea delivered to an exhaust system upstream of a catalytic converter.