diff --git a/CHANGES.md b/CHANGES.md
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@@ -7,6 +7,7 @@
 
 ### New Features: ###
 
+- The transmit calibration tone (-x) command line option now accepts a radio channel number and/or a single letter mode:  a = alternate tones, m = mark tone, s = space tone, p = PTT only no sound.
 
 - The BEACON configuration now recognizes the SOURCE= option.  This replaces the AX.25 source address rather than using the MYCALL value for the channel.  This is useful for sending more than 5 analog telemetry channels.  Use two, or more, source addresses with up to 5 analog channels each.