diff --git a/executables/nr-ru.c b/executables/nr-ru.c
index 7837f3740980dff1a58ca180822257cdb55da0eb..f3c1e15efe78571c34ecf0051d84ba88a32024f8 100644
--- a/executables/nr-ru.c
+++ b/executables/nr-ru.c
@@ -1465,7 +1465,14 @@ void *ru_thread( void *param ) {
     if ((ru->is_slave) && (ru->if_south == LOCAL_RF)) do_ru_synch(ru);
 
     // start trx write thread
-    ru->start_write_thread(ru);
+    if (ru->start_write_thread){
+      if(ru->start_write_thread(ru) != 0){
+        LOG_E(HW,"Could not start tx write thread\n");
+      }
+      else{
+        LOG_I(PHY,"tx write thread ready\n");
+      }
+    }
   }
 
   pthread_mutex_lock(&proc->mutex_FH1);
@@ -2099,6 +2106,7 @@ void set_function_spec_param(RU_t *ru) {
       ru->fh_south_asynch_in     = NULL;                // no asynchronous UL
       ru->start_rf               = NULL;                // no local RF
       ru->stop_rf                = NULL;
+      ru->start_write_thread     = NULL;
       ru->nr_start_if            = nr_start_if;         // need to start if interface for IF5
       ru->ifdevice.host_type     = RAU_HOST;
       ru->ifdevice.eth_params    = &ru->eth_params;
@@ -2125,6 +2133,7 @@ void set_function_spec_param(RU_t *ru) {
       ru->fh_north_asynch_in     = NULL;
       ru->start_rf               = NULL;                // no local RF
       ru->stop_rf                = NULL;
+      ru->start_write_thread     = NULL;
       ru->nr_start_if            = nr_start_if;         // need to start if interface for IF4p5
       ru->ifdevice.host_type     = RAU_HOST;
       ru->ifdevice.eth_params    = &ru->eth_params;
diff --git a/targets/PROJECTS/GENERIC-LTE-EPC/CONF/gnb.band78.tm1.106PRB.usrpn300.conf b/targets/PROJECTS/GENERIC-LTE-EPC/CONF/gnb.band78.tm1.106PRB.usrpn300.conf
index 0d66385dcfce0f05d297fb0ded536130174c114c..fed15739cf55e3b00aa9e56a5cc4a4e6536ab9fc 100644
--- a/targets/PROJECTS/GENERIC-LTE-EPC/CONF/gnb.band78.tm1.106PRB.usrpn300.conf
+++ b/targets/PROJECTS/GENERIC-LTE-EPC/CONF/gnb.band78.tm1.106PRB.usrpn300.conf
@@ -238,7 +238,7 @@ RUs = (
          max_rxgain                    = 114;
          eNB_instances  = [0];
 	 sdr_addrs = "addr=192.168.10.2,mgmt_addr=192.168.10.2,second_addr=192.168.20.2";
-         clock_src = "internal";
+         clock_src = "external";
     }
 );