diff --git a/ptb2.json b/ptb2.json
index 9f6e612..785412f 100644
--- a/ptb2.json
+++ b/ptb2.json
@@ -32,13 +32,13 @@
             "type": "urukul",
             "ports": [5, 4],
             "dds": "ad9912",
-            "clk_sel": 0
+            "clk_sel": 2
         },
         {
             "type": "urukul",
             "ports": [6],
             "synchronization": true,
-            "clk_sel": 0
+            "clk_sel": 2
         },
         {
             "type": "zotino",