Direct Comparison of DC Josephson Voltage Standard and Programmable Josephson Voltage Standard of TÜBİTAK UME

10 V programmable Josephson voltage standard (PJVS) has been setup at TÜBİTAK Ulusal Metroloji Enstitüsü(UME), national metrology institute of Turkey. The PJVS has compared to 10 V DC Josephson Array Voltage Standard (JVS) of TÜBİTAK UME which is regularly used for the calibration of DC Voltage Standards and DC voltage meters since 1997. A direct comparison between two Josephson voltage standards was carried out at the level of 10 V in order to verify the accuracy of the PJVS. The difference between the two systems (JVS - PJVS) was \pmb+0.96nV with an uncertainty of 2.4 parts in \pmb10
^-10
\pmb(k=1).