diff --git a/codec2talkie/src/main/java/com/radio/codec2talkie/protocol/AprsIs.java b/codec2talkie/src/main/java/com/radio/codec2talkie/protocol/AprsIs.java
index 7802976..dc01b28 100644
--- a/codec2talkie/src/main/java/com/radio/codec2talkie/protocol/AprsIs.java
+++ b/codec2talkie/src/main/java/com/radio/codec2talkie/protocol/AprsIs.java
@@ -11,6 +11,7 @@ import androidx.preference.PreferenceManager;
 import com.radio.codec2talkie.BuildConfig;
 import com.radio.codec2talkie.R;
 import com.radio.codec2talkie.protocol.aprs.AprsCallsign;
+import com.radio.codec2talkie.protocol.aprs.tools.AprsHeardList;
 import com.radio.codec2talkie.protocol.aprs.tools.AprsIsData;
 import com.radio.codec2talkie.protocol.message.TextMessage;
 import com.radio.codec2talkie.protocol.position.Position;
@@ -40,6 +41,8 @@ public class AprsIs implements Protocol, Runnable {
     private static final int APRSIS_RETRY_WAIT_MS = 10000;
     private static final int APRSIS_DEFAULT_PORT = 14580;
 
+    private static final int HEARD_LIST_DURATION_SECONDS = 60;
+
     private final Protocol _childProtocol;
     private Context _context;
     private ProtocolCallback _parentProtocolCallback;
@@ -62,6 +65,8 @@ public class AprsIs implements Protocol, Runnable {
     private final ByteBuffer _toAprsIsQueue;
     private final byte[] _rxBuf;
 
+    private final AprsHeardList _rfHeardList = new AprsHeardList(HEARD_LIST_DURATION_SECONDS);
+
     protected boolean _isRunning = true;
     private boolean _isConnected = false;
 
@@ -80,7 +85,7 @@ public class AprsIs implements Protocol, Runnable {
 
         SharedPreferences sharedPreferences = PreferenceManager.getDefaultSharedPreferences(context);
         _isRxGateEnabled = sharedPreferences.getBoolean(PreferenceKeys.APRS_IS_ENABLE_RX_GATE, false);
-        _isTxGateEnabled = false; // sharedPreferences.getBoolean(PreferenceKeys.APRS_IS_ENABLE_TX_GATE, false);
+        _isTxGateEnabled = sharedPreferences.getBoolean(PreferenceKeys.APRS_IS_ENABLE_TX_GATE, false);
         _isSelfEnabled = sharedPreferences.getBoolean(PreferenceKeys.APRS_IS_ENABLE_SELF, false);
         _callsign = sharedPreferences.getString(PreferenceKeys.AX25_CALLSIGN, "N0CALL").toLowerCase(Locale.ROOT);
         _digipath = sharedPreferences.getString(PreferenceKeys.AX25_DIGIPATH, "").toUpperCase();
@@ -132,13 +137,14 @@ public class AprsIs implements Protocol, Runnable {
         /* rules:
             1. RX gate must be heard on rf within digi hops or range
             2. RX gate has not been heard on internet within given period of time or in third party packets
-            3. sender must not be heard within given period of time on RF
+            3. ✓ sender must not be heard within given period of time on RF
             4. ✓ sender must not have TCPXX, NOGATE, RFONLY
         */
         AprsCallsign aprsCallsign = new AprsCallsign(aprsIsData.src);
         return _isTxGateEnabled &&
                 aprsCallsign.isValid &&
                 !_isLoopbackTransport &&
+                !_rfHeardList.contains(aprsIsData.src) &&
                 aprsIsData.isEligibleForTxGate();
     }
 
@@ -192,6 +198,7 @@ public class AprsIs implements Protocol, Runnable {
 
         @Override
         protected void onReceiveData(String src, String dst, String path, byte[] data) {
+            _rfHeardList.add(src);
             if (_isRxGateEnabled && !_isLoopbackTransport) {
                 // NOTE, https://aprs-is.net/IGateDetails.aspx
                 AprsIsData aprsIsData = new AprsIsData(src, dst, path, new String(data));
diff --git a/codec2talkie/src/main/java/com/radio/codec2talkie/protocol/aprs/tools/AprsHeardList.java b/codec2talkie/src/main/java/com/radio/codec2talkie/protocol/aprs/tools/AprsHeardList.java
index ce4e3e1..b378899 100644
--- a/codec2talkie/src/main/java/com/radio/codec2talkie/protocol/aprs/tools/AprsHeardList.java
+++ b/codec2talkie/src/main/java/com/radio/codec2talkie/protocol/aprs/tools/AprsHeardList.java
@@ -1,15 +1,10 @@
 package com.radio.codec2talkie.protocol.aprs.tools;
 
 import java.util.Map;
-
-import java.util.Timer;
-import java.util.TimerTask;
 import java.util.TreeMap;
 
 public class AprsHeardList {
 
-    private final int CLEANUP_PERIOD_MS = 30000;
-
     private static class AprsHeardListItem {
         public long timestamp;
         public String callsign;
@@ -25,7 +20,6 @@ public class AprsHeardList {
 
     public AprsHeardList(int keepSeconds) {
         _keepSeconds = keepSeconds;
-        scheduleCleanup();
     }
 
     public void add(String callsign) {
@@ -37,32 +31,22 @@ public class AprsHeardList {
             } else {
                 heardItem.timestamp = System.currentTimeMillis();
             }
+            cleanup();
         }
     }
 
     public boolean contains(String callsign) {
         synchronized (_data) {
+            cleanup();
             return _data.containsKey(callsign);
         }
     }
 
-    private void scheduleCleanup() {
-        Timer cleanupTimer = new Timer();
-        cleanupTimer.schedule(new TimerTask() {
-            @Override
-            public void run() {
-                cleanup();
-            }
-        }, CLEANUP_PERIOD_MS, CLEANUP_PERIOD_MS);
-    }
-
     private void cleanup() {
         long removeOlderThan = System.currentTimeMillis() - _keepSeconds * 1000L;
-        synchronized (_data) {
-            for (Map.Entry<String, AprsHeardListItem> entryElement : _data.entrySet()) {
-                if (entryElement.getValue().timestamp < removeOlderThan) {
-                    _data.remove(entryElement.getKey());
-                }
+        for (Map.Entry<String, AprsHeardListItem> entryElement : _data.entrySet()) {
+            if (entryElement.getValue().timestamp < removeOlderThan) {
+                _data.remove(entryElement.getKey());
             }
         }
     }
diff --git a/codec2talkie/src/main/res/xml/preferences_aprs_is.xml b/codec2talkie/src/main/res/xml/preferences_aprs_is.xml
index ff3bd04..5dffe4e 100644
--- a/codec2talkie/src/main/res/xml/preferences_aprs_is.xml
+++ b/codec2talkie/src/main/res/xml/preferences_aprs_is.xml
@@ -27,7 +27,6 @@
 
         <SwitchPreference
             app:key="aprs_is_enable_tx_gate"
-            app:enabled="false"
             app:title="@string/aprs_is_enable_tx_gate_title"
             app:summary="@string/aprs_is_enable_tx_gate_summary"
             app:defaultValue="false">