diff --git a/chirp/drivers/tdh8.py b/chirp/drivers/tdh8.py
index c26fedece..74b89da10 100644
--- a/chirp/drivers/tdh8.py
+++ b/chirp/drivers/tdh8.py
@@ -696,7 +696,7 @@ def get_features(self):
             "->Tone",
             "DTCS->DTCS"]
         rf.valid_power_levels = TX_POWER
-        rf.valid_duplexes = ["", "-", "+", "split"]
+        rf.valid_duplexes = ["", "-", "+", "split", "off"]
         rf.valid_modes = ["FM", "NFM"]
         rf.valid_tuning_steps = STEPS
 
@@ -851,6 +851,9 @@ def get_memory(self, number):
         if int(_mem.rxfreq) == int(_mem.txfreq):
             mem.duplex = ""
             mem.offset = 0
+        elif int(_mem.txfreq) == 66666665 and int(_mem.rxfreq) != 66666665:
+            mem.offset = 0
+            mem.duplex = 'off'
         else:
             mem.duplex = int(_mem.rxfreq) > int(_mem.txfreq) and "-" or "+"
             mem.offset = abs(int(_mem.rxfreq) - int(_mem.txfreq)) * 10
@@ -1018,6 +1021,8 @@ def set_memory(self, mem):
             _mem.txfreq = (mem.freq + mem.offset) / 10
         elif mem.duplex == "-":
             _mem.txfreq = (mem.freq - mem.offset) / 10
+        elif mem.duplex == 'off':
+            _mem.txfreq = 166666665
         else:
             _mem.txfreq = mem.freq / 10