The present invention is a high Q tunable co-axial filter, which maintains a constant absolute bandwidth and a constant Q over the tuning range. The present filter can be tuned by a single rotational mechanism irrespective of the filter order. A plurality of tunable resonators is aligned on a common filter axis. Each resonator has a casing having an inner wall and a cavity. The resonators are coupled by an iris opening. A pair of end plates completes the filter casing. A rotating rod placed on the common axis of the resonated, that has a tuning post attached to it, and each post located in each resonator, is used to tune the filter.