Due to overheating of the antenna elements, Leica changed the original SR-399 antenna mount design in August 1997, beginning with antenna serial number S/N 70501. The antenna calibrations for the newer mounting differ significantly from the calibrations for the original mount design. NGS’ original SR-399 calibrations were for the older antenna mount. The revised SR-399 design had never been submitted for calibration. Calibrations for the newer antenna mount design have now been completed. Please note the following:

LEISR399_INT will refer to the calibrations for the revised antenna mount design

LEISR399_INTA will refer to the calibrations for the original antenna mount design

Users will be responsible for knowing which antenna version that they are using. Leica also advises that any older SR-399’s with the original mount design, that were submitted for servicing were automatically upgraded to the newer design. Users should check their service records or contact the manufacturer if they are uncertain which antenna version that they may have.