Download and install the USB driver for the radio. NOTE: be sure the USB cable is UNPLUGGED from the computer when you install the driver regardless of the OS your are using.
- If you’re using Windows get the driver from Yaesu.
- If using Linux or MacOS then get the drivers direct from Silicon Labs. Some versions of Linux have a driver built in.
- For MacOS High Sierra and later be sure to go to Security & Privacy in the System Configuration settings and in the General tab allow the driver to be accessed. Without doing that it will be unusable.
Download the latest version of Fldigi. Flrig is written as a companion to fldigi and adds much greater rig control than is possible with just fldigi. It is especially good with the FT991A. I basically only touch the radio to turn it on or off when running digital modes, and even that can be automated.

Transceiver setup

FT-991A Menu Settings

On the rig, press the MENU button. Then change these menu items as shown:

Menu #	Name	Value
31	CAT RATE	38400 bps
32	CAT TOT	10 msec
33	CAT RTS	ENABLE
59	CW FREQ DISPLAY	PITCH OFFSET
60	PC KEYING	DTR
62	DATA MODE	OTHERS
63	PSK TONE	1500 hZ
64	OTHER DISP (SSB)	1500 Hz
65	OTHER SHIFT (SSB)	1500 Hz
66	DATA LCUT FREQ	300 Hz
67	DATA LCUT SLOPE	18 dB/oct
68	DATA HCUT FREQ	3600 Hz
69	DATA HCUT SLOPE	18 dB/oct
70	DATA IN SELECT	REAR
71	DATA PTT SELECT	DAKY
72	DATA PORT SELECT	USB
73	DATA OUT LEVEL (RX)	100
74	FM MIC SELECT (PHONE)	MIC
75	FM OUT LEVEL (Rx)	50
76	FM PKT PTT SELECT	DTR
77	FM PKT PORT SELECT	DATA
106	SSB MIC SELECT	MIC
107	SSB OUT LEVEL	50
108	SSB PTT SELECT	DAKY
109	SSB PORT SELECT	USB
110	SSB TX BPF	300-2700
114	IF NOTCH WIDTH	NARROW
146	DATA VOX GAIN	50
147	DATA VOX DELAY	100 msec
148	ANTI DVOX GAIN	0

You should have already installed the driver for the built-in sound card in the FT-991A.

Connect the rig to the computer with a USB A-Male to B-Male cable and turn on the radio.

Initial Setup

With the radio on and the USB cable connected and no other communications program running, Start flrig. It will come up with just a basic display.

Initial Flrig Dialog

Open the menu Config/Setup/Transceiver.

Select FT991A

Choose the FT991A from the Rig dropdown list. That will select the default settings which will work on . Note: The RTS +12v and DTR +12v boxes do not normally need to be checked.

Select the Serial Port to use:

Mac / Linux - Select the SilconLabs driver from the dropdown list. If it isn't in the list then click the SerPort button to repopulate the list. It if still isn't in the list then the driver is not loading for some reason like the radio is not on or connected or the driver has not been installed properly so that needs to be rectified before going on. If you're using MacOS High Sierra or a later version of MacOS you may need to authorize the driver install in Security & Privacy setup in System Preferences after runing the install program. There will be a message on the General page if it has been blocked.
Windows - Open the device manager and determine to which com port the serial driver from Silcon Labs is assigned and choose that from the drop down list.
Verify that the Baud rate in flrig matches the baud rate selected in the rig. It's better to choose a fixed baud rate than Auto. Now, click the Init button. It should go from red to black lettering. If it does not go to black lettering then verify all of the above again, especially baud rate and echo.
Flrig now should have control of the rig so changing frequency in flrig will changed the frequency on the rig and visa versa. The buttons and sliders should do as they are labeled.

Restore tab:

and choose whether you want flrig to save and restore all the radio’s parameters on startup and exit or whether you want it to open with the same settings as the rig is currently using. If Use xcvr data is checked flrig will start up with the same settings as the rig currently is using.

Poll tab

and click the Set All buttons for the initial polling options. You can play with these values later if you wish. The larger the number the slower the response time to button pushes etc, but also the less load on the system so there is a balance. A very fast machine can use all ones, but there is normally no need to add the additional load to your system for that.

I would recommend before you move on that you go to the Config/UI menu and select Tooltips. They are a great help to the new user to figure out what each control does as not all are labeled. You can choose 4 different UI’s from the narrow one with small sliders (I use this one – see above screen shot of flrig), to a narrow one with large sliders, to a wide version or a touch version. Now close flrig and restart it to be sure all is well . Everything should be working and you should be able to change frequency on the radio and flrig should follow.

flrig/FT991A/fldigi

Start fldigi and fill in the initial setup pages presented. You can ignore the last page for now. All these pages can be accessed via the configuration menu later to be changed as you wish. Since you've chosen to use flrig then go to the fldigi menu “Configuration/Rig control/flrig” and check the top box to tell fldigi to use flrig for rig control with fldigi as client.
Leave the other controls at their default setting.

Once that is done fldigi should communicate with flrig and changes such as frequency or bandwidth in flrig or fldigi should be reflected in the other. If the lower box is checked then flrig will send fldigi audio to the radio when the PTT button is clicked otherwise PTT will just key the rig with no power out. Click Save at the bottom of the page.

All that is left is to customize fldigi for how you want to operate. Many things can be changed such as the UI scheme, colors, Macros, and many more. Read the help manual to learn about all the options and features that are available.

Final Setup

With fldigi running verify you have a blue waterfall running. If you don't see that then there is a problem with the audio input to fldigi. Verify the Soundcard setup.

Note:

For MacOS Mojave and later you must enable the microphone for fldigi in Security & Privacy in the System Preferences settings.
For Windows 10 be sure to grant permission for fldigi to access the Microphone.

Now we will verify the power out of the radio. Set the radio power control on the rig to max, 100% and leave it there.

Set Power Meter scale: Right click on the lower portion of the S-meter scale and choose the power scale desired. The max digital power out used for a QSO should cause no ALC action on the radio. The FT991A will put out quite a bit of power without ALC action, but you don't want to interfere with other close signals on the band either so ideally the power should be between 25-40 watts.

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