Telephonics RDR1400C WX & SAR Radar
 

Does anyone know what the range accuracy of this radar is at 2.5NM scale? Alternatively, does anybody have the TSO-C102 MPS specs for range accuracy of airborne radars used for approaches?

I think you will find that it at least meets the requirement for ±0.2 NM at display ranges of 5 NM or less. These are contained in AC 90-80B Chapter 2 of this advisory circular dated 1999.