Biplanar vacuum diodes, long used for the diagnostics of laser‐produced plasmas, have also been used as spectroscopic survey instruments for magnetically confined plasmas. The compact seven‐channel diode array, developed at KMS Fusion, provides broadband (&Dgr;E/E&bartil;1) channels of filtered cathodes to provide the spectral scan from 10 eV to about 5 keV (approximately 130 to 0.25 nm). Preliminary calibration results and calculations for a number of filters and cathodes are used to demonstrate that a satisfactory energy region may be obtained if an absorption edge of the cathode is below the mean energy of the desired channel and an absorption edge of the filter is above that energy. These devices are insensitive to neutron and gamma flux.