There are about 10 useful pionic X-ray transitions in the energy region between 2 and 3 keV available from low Z gases. Their rates, however, are not sufficient to do a time consuming optimization of the crystal resolution. A solution of this problem is the production of X-rays from one- or two-electron atoms. They can be delivered copiously by electron cyclotron resonance (ECR) sources, which have been developed as ion sources for accelerators. The line width of the X-rays is determined almost exclusively by a very much reduced Doppler effect which leads to negligible broadenings compared to the intrinsic resolution of the crystals. Presently such a source is being set up at PSI. It is planned to test it first with Si crystals which have been studied extensively during recent years. In a second step the response function of quartz crystals will be optimized and fluorescence sources will be calibrated. During the measurement with pions and muons the crystals can then be routinely surveyed with pionic X-rays which in turn can be used to energy calibrate the ECR measurement on the ppm level.