diff --git a/onbeat_rx.grc b/onbeat_rx.grc
index dda1430..d980444 100644
--- a/onbeat_rx.grc
+++ b/onbeat_rx.grc
@@ -78,6 +78,27 @@ blocks:
     coordinate: [192, 92.0]
     rotation: 0
     state: true
+- name: rx_gain
+  id: variable_qtgui_range
+  parameters:
+    comment: ''
+    gui_hint: ''
+    label: RX gain
+    min_len: '200'
+    orient: QtCore.Qt.Horizontal
+    rangeType: float
+    start: '0'
+    step: '0.1'
+    stop: '49.6'
+    value: '20'
+    widget: counter_slider
+  states:
+    bus_sink: false
+    bus_source: false
+    bus_structure: null
+    coordinate: [160, 256.0]
+    rotation: 0
+    state: true
 - name: samp_rate
   id: variable
   parameters:
diff --git a/onbeat_rx_wrapper.py b/onbeat_rx_wrapper.py
index bcd0273..1ad4a04 100644
--- a/onbeat_rx_wrapper.py
+++ b/onbeat_rx_wrapper.py
@@ -37,5 +37,5 @@ received = asyncio.run(tcp_client())
 
 
 
-with open("rx_packets.json") as packetfile:
+with open("rx_packets.json", mode="w") as packetfile:
     json.dump(received, packetfile)