A heat exchanger includes a flattened tube 10 having a plurality of internal ports 22 extending to the end 12 thereof. The method may include the steps of providing an applicator, feeding the cement mixture into applicator, forcing the cement mixture to exit the applicator with a substantially uniform velocity, while depositing the cement mixture on the exposed matrix of the honeycomb body. The plurality of imagers include a first imager having a first imaging characteristics and a second imager having a second imaging characteristics. In this structure, in the case where an input signal is changed from L to H, the PVT sensitivity of a delay circuit is automatically alleviated.