Fix ftdx101d set_freq behavior depending on split mode and VFO requested

rigs/yaesu/newcat.c

@@ -779,8 +779,11 @@ int newcat_set_freq(RIG *rig, vfo_t vfo, freq_t freq)
     // but they can change the TX vfo
     if (is_ftdx101 && rig->state.cache.ptt == RIG_PTT_ON)
     {
-        // then we can't change freq on the non-tx VFO
         rig_debug(RIG_DEBUG_TRACE, "%s: ftdx101 check vfo OK, vfo=%s, tx_vfo=%s\n", __func__, rig_strvfo(vfo), rig_strvfo(rig->state.tx_vfo));
+        // when in split we can change VFOB but not VFOA
+        if (rig->state.split == RIG_SPLIT_ON && target_vfo == '0') return -RIG_ENTARGET;
+        // when not in split we can't change VFOA at all
+        if (rig->state.split == RIG_SPLIT_OFF && target_vfo == '0') return -RIG_ENTARGET;
         if (vfo != rig->state.tx_vfo) return -RIG_ENTARGET;
     }