diff --git a/doc/user_guide/controls-functions-main-window.adoc b/doc/user_guide/controls-functions-main-window.adoc
index 2c27bcc87..723b0c106 100644
--- a/doc/user_guide/controls-functions-main-window.adoc
+++ b/doc/user_guide/controls-functions-main-window.adoc
@@ -22,7 +22,7 @@ file.
 * *Monitor* restarts normal receive operation.  This button is
 highlighted in green when the _WSJT-X_ is receiving.  If you are
 using CAT control, toggling *Monitor* OFF relinquishes control of the
-rig; if *Monitor returns to last used frequency" is selected
+rig; if _Monitor returns to last used frequency_ is selected
 on the *Settings | General* tab, toggling *Monitor* back ON will
 return to the original frequency.
 
diff --git a/doc/user_guide/images/echo_144.png b/doc/user_guide/images/echo_144.png
index e4a4e16d0..58668c68b 100644
Binary files a/doc/user_guide/images/echo_144.png and b/doc/user_guide/images/echo_144.png differ
diff --git a/doc/user_guide/introduction.adoc b/doc/user_guide/introduction.adoc
index e3ed86e5b..687f80e48 100644
--- a/doc/user_guide/introduction.adoc
+++ b/doc/user_guide/introduction.adoc
@@ -6,8 +6,8 @@ the program name stand for “Weak Signal communication by K1JT,” while
 the suffix “-X” indicates that _WSJT-X_ started as an extended (and
 experimental) branch of the program _WSJT_.
 
-_WSJT-X_ Version 1.6 offers four protocols or “modes”: JT4, JT9, JT65
-and WSPR.  The first three are designed for making reliable 
+_WSJT-X_ Version 1.6 offers five protocols or “modes”: JT4, JT9, JT65
+WSPR, and Echo.  The first three are designed for making reliable 
 QSOs under extreme weak-signal conditions. They use nearly identical
 message structure and source encoding.  JT65 was designed for EME
 (“moonbounce”) on the VHF/UHF bands and has also proven very effective
diff --git a/mainwindow.cpp b/mainwindow.cpp
index 939437d85..b09f6eecf 100644
--- a/mainwindow.cpp
+++ b/mainwindow.cpp
@@ -3690,7 +3690,7 @@ void MainWindow::getpfx()
            <<"FOA" <<"FOC" <<"FOM" <<"FP" <<"FR" <<"FRG" <<"FRJ" <<"FRT" \
            <<"FT5W" <<"FT5X" <<"FT5Z" <<"FW" <<"FY" <<"M" <<"MD" <<"MI" \
            <<"MJ" <<"MM" <<"MU" <<"MW" <<"H4" <<"H40" <<"HA" \
-           <<"HB" <<"HB0" <<"HC" <<"HC8" <<"HH" <<"HI" <<"HK" <<"HK0A" \
+           <<"HB" <<"HB0" <<"HC" <<"HC8" <<"HH" <<"HI" <<"HK" <<"HK0" \
            <<"HK0M" <<"HL" <<"HM" <<"HP" <<"HR" <<"HS" <<"HV" <<"HZ" \
            <<"I" <<"IS" <<"IS0" <<"J2" <<"J3" <<"J5" <<"J6" \
            <<"J7" <<"J8" <<"JA" <<"JDM" <<"JDO" <<"JT" <<"JW" \