diff --git a/overlay/etc/udev/rules.d/78-et-ft991a.rules b/overlay/etc/udev/rules.d/78-et-ft991a.rules
new file mode 100644
index 0000000..4dc2f96
--- /dev/null
+++ b/overlay/etc/udev/rules.d/78-et-ft991a.rules
@@ -0,0 +1,37 @@
+# Author   : Gaston Gonzalez
+# Date     : 8 December 2024
+# Purpose  : udev rules for the Yaesu FT-991A via native USB
+#
+# Preconditions:
+# 1. Yaesu FT-991A is selected via et-radio
+# 2. Yaesu FT-991A is powered on and connected via USB cable
+#
+# Postconditions:
+# 1. /dev/et-cat created
+# 2. /dev/et-audio created
+# 3. rigctld is started
+# 
+# CAUTION: The FT-991A is an experimental device that may impact the stability of the platform and may
+#          not work 100% of the time. This device support is best effort only.
+
+# Special rule to ensure that the first serial interface (/dev/ttyUSB4) is tagged as ET_DEVICE=FT-891 so
+# that it can be used in the next CAT control rule. The second serial device will not work (/dev/ttyUSB5)
+# if it is incorrectly detected as the /dev/et-cat device.
+KERNEL=="ttyUSB[0-9]*", SUBSYSTEM=="tty", PROGRAM="/opt/emcomm-tools/sbin/udev-tester.sh yaesu-ft991a", \
+    ATTRS{bInterfaceNumber}=="00", \
+    ENV{ET_DEVICE}="FT-991A"
+
+# CAT control device will only match if PROGRAM above matches (exit status=0)
+SUBSYSTEM=="tty", ENV{ET_DEVICE}=="FT-991A", \
+    ATTRS{idVendor}=="10c4", ATTRS{idProduct}=="ea70",\
+    ACTION=="add", \
+    ENV{ET_SUBDEVICE}="CAT", GROUP="dialout", MODE="0660", SYMLINK+="et-cat", \
+    RUN+="/usr/bin/systemctl start rigctld"
+
+# Audio device will only match if PROGRAM above matches (exit status=0)
+SUBSYSTEM=="sound", ATTRS{idVendor}=="08bb", ATTRS{idProduct}=="29b3", \
+    PROGRAM="/opt/emcomm-tools/sbin/udev-tester.sh yaesu-ft991a", \
+    ACTION=="add", \
+    ENV{ET_DEVICE}="FT-991A", \
+    ATTR{id}="ET_AUDIO", \
+    ENV{ET_SUBDEVICE}="AUDIO", GROUP="audio", MODE="0660", SYMLINK+="et-audio"
diff --git a/overlay/opt/emcomm-tools/conf/radios.d/yaesu-ft991a.json b/overlay/opt/emcomm-tools/conf/radios.d/yaesu-ft991a.json
new file mode 100644
index 0000000..4e27507
--- /dev/null
+++ b/overlay/opt/emcomm-tools/conf/radios.d/yaesu-ft991a.json
@@ -0,0 +1,33 @@
+{
+  "id": "yaesu-ft991a",
+  "vendor": "Yaesu",
+  "model": "FT-991A",
+  "rigctrl": {
+    "id": "1035",
+    "baud": "38400",
+    "ptt": "RIG"
+  },
+  "notes": [
+    "031 CAT RATE = 38400bps",
+    "032 CAT TOT = 100ms",
+    "033 CAT RTS = DISABLE",
+    "062 DATA MODE = OTHERS",
+    "064 OTHER DISP (SSB) = 1500Hz",
+    "065 OTHER SHIFT (SSB) = 1500Hz",
+    "066 DATA LCUT FREQ = OFF",
+    "068 DATA HCUT FREQ = OFF",
+    "070 DATA IN SELECT = REAR",
+    "071 DATA PTT SELECT = DAKY",
+    "072 DATA PORT SELECT = USB",
+    "073 DATA OUT LEVEL = 50",
+    "076 FM PKT PTT SELECT = DAKY",
+    "077 FM PKT PORT SELECT = USB",
+    "078 FM PKT TX GAIN = 50",
+    "079 FM PKT MODE = 1200",
+    "For HF digital operation always set Mode = DATA-USB",
+    "For HF digital operation always set WDH = 3000Hz",
+    "For FM packet operation always set Mode = DATA-FM"
+  ],
+  "fieldNotes": [
+  ]
+}
diff --git a/overlay/opt/emcomm-tools/sbin/udev-tester.sh b/overlay/opt/emcomm-tools/sbin/udev-tester.sh
index 878ee0e..28565b4 100755
--- a/overlay/opt/emcomm-tools/sbin/udev-tester.sh
+++ b/overlay/opt/emcomm-tools/sbin/udev-tester.sh
@@ -1,7 +1,7 @@
 #!/bin/bash
 # Author  : Gaston Gonzalez
 # Date    : 11 October 2024
-# Updated : 21 November 2024
+# Updated : 8 December 2024
 # Purpose : Perform tests that can be used by the udev subsystem to aid
 #           in rule development. This is intended to by used with the PROGRAM
 #           directive inside of a udev rule.
@@ -13,7 +13,7 @@
 ET_HOME=/opt/emcomm-tools
 ACTIVE_RADIO="${ET_HOME}/conf/radios.d/active-radio.json"
 
-# Exit with a 0 exit success if, and only if, the currently selected radio is
+# Exit with a 0 exit status if, and only if, the currently selected radio is
 # a Yaesu FT-891.
 test_yaesu_ft891() {
   if [ -L "${ET_HOME}/conf/radios.d/active-radio.json" ]; then
@@ -27,7 +27,21 @@ test_yaesu_ft891() {
   exit 1
 }
 
-# Exit with a 0 exit success if, and only if, the currently selected radio 
+# Exit with a 0 exit status if, and only if, the currently selected radio is
+# a Yaesu FT-991A.
+test_yaesu_ft991a() {
+  if [ -L "${ET_HOME}/conf/radios.d/active-radio.json" ]; then
+    ID=$(cat "${ET_HOME}/conf/radios.d/active-radio.json" | jq -r .id)
+
+    if [[ "$ID" == "yaesu-ft991a" ]]; then
+      exit 0
+    fi
+  fi
+  
+  exit 1
+}
+
+# Exit with a 0 exit status if, and only if, the currently selected radio 
 # uses a DigiRig Mobile.
 test_digirig_mobile() {
   if [ -L "${ET_HOME}/conf/radios.d/active-radio.json" ]; then
@@ -71,6 +85,9 @@ case $1 in
   yaesu-ft891)
     test_yaesu_ft891
   ;;
+  yaesu-ft991a)
+    test_yaesu_ft991a
+  ;;
   digirig-mobile)
     test_digirig_mobile
 esac