Fix 'S 1 Sub' for icom rigs with A/B only

rigs/icom/icom.c

@@ -4231,14 +4231,23 @@ int icom_set_split_vfo(RIG *rig, vfo_t vfo, split_t split, vfo_t tx_vfo)
             priv->tx_vfo = RIG_VFO_A;
             priv->rx_vfo = RIG_VFO_A;
         }
-        // otherwise if Main or Sub we set Main as the current vfo
+        // otherwise if Main or Sub we set Main or VFOA as the current vfo
         else if (tx_vfo == RIG_VFO_MAIN || tx_vfo == RIG_VFO_SUB)
         {
             rig_debug(RIG_DEBUG_TRACE, "%s: set_vfo to VFO_MAIN because tx_vfo=%s\n",
                       __func__, rig_strvfo(tx_vfo));
             rig_set_vfo(rig, RIG_VFO_MAIN);
-            priv->tx_vfo = RIG_VFO_MAIN;
-            priv->rx_vfo = RIG_VFO_MAIN;
+
+            if (VFO_HAS_A_B_ONLY)
+            {
+                priv->tx_vfo = RIG_VFO_A;
+                priv->rx_vfo = RIG_VFO_A;
+            }
+            else
+            {
+                priv->tx_vfo = RIG_VFO_MAIN;
+                priv->rx_vfo = RIG_VFO_MAIN;
+            }
         }
 
         split_sc = S_SPLT_OFF;