Yes, the IN-2025A can be used in the RDR-1400C Radar System only if the IN-2025A has Mods 13 and 15. IN-2025A indicators with Serial Number 1610 and above have these mods already incorporated. These mods convert the IN-2025A indicator to display both standard two-pulse beacon replys and to also display the DO-172 six-pulse beacon replys. The resulting modified indicator is functionally equivalent to the IN-2025B radar indicator.