Yaesu FT991A
The FT991A has USB Com ports and USB Audio available for digital mode.
The audio source from the radio is listed as “USB Audio Codec” and it may or may not have a number.
FT991A CAT Control
Serial Device should be the “Enhanced” comport:
and select the Serial Rate to match the option 31 (CAT Rate) in the radio menu.
Ensure that the Use USB/LSB instead of DIGU/DIGL is not enabled.
FT991A Radio Settings
The settings for FreeDV are similar to other Digital modes:
| Setting | Name | Value |
| 029 | 232C Rate | 38400bps |
| 030 | 232 ToT | 10msec |
| 031 | Cat Rate | 38400 |
| 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 |
Geoff found that when using FreeDV, each time he started the modem, the frequency would shift by 700kHz.
This can be remedied by this setting:
| 059 | CW Freq Display | Direct Freq |
Yaesu FT891A
The FT891 has USB Com ports but no USB Audio available for digital mode.
While the Yaesu FT891 does not have an audio interface, and there are a number of options available which connect via one of the DIN ports on the back of the radio to a USB Audio interface.
In my setup the Audio device from the radio is listed as “USB Audio Device” but yours may be different.
FT891A CAT Control
Serial Device should be the “Enhanced” comport:
and select the Serial Rate to match the option 05-06 (CAT Rate) in the radio menu.
Ensure that the Use USB/LSB instead of DIGU/DIGL is not enabled.
FT891 Radio Settings
The settings for FreeDV are like other Digital modes:
| Setting | Name | Value |
| 05-06 | CAT RATE | 38400bps |
| 05-07 | CAT TOT | 10msec |
| 05-08 | CAT RTS | Enable |
| 07-12 | PC KEYING | Off |
| 08-01 | DATA MODE | Others |
| 08-03 | OTHER DISP | 1500Hz |
| 08-04 | OTHER SHIFT | 1500Hz |
| 08-05 | DATA LCUT FREQ | OFF |
| 08-07 | DATA HCUT FREQ | OFF |
| 08-09 | DATA IN SELECT | REAR |
| 08-10 | DATA PTT SELECT | RTS |
| 08-11 | DATA OUT LEVEL | 50 |
| 08-12 | DATA BFO | LSB |
Geoff found that when using FreeDV, each time I started the modem, the frequency would shift by 700kHz.
This can be remedied by this setting:
| 7-11 | Freq Display | Freq |
FreeDV Serial PTT
An interesting thing Geoff does, which is not specific to Yaesu, is that he’s made up a manual PTT switch that works via a serial port.
Enable Serial PTT in FreeDV:
This enables a push to talk button in FreeDV, so hitting the space bar or using the mouse it not required.
Hold button in to talk, release when finished.
This solution works under both Linux and Windows of the FreeDV 2.1.0 (and earlier) release.
You will need a COM Port on the system or a USB to Serial cable (eg Profilic Techology).
As long as it supports all RTS/CTS signals on the serial port. I picked one up in Jaycar a while ago
Install the correct driver under Windows, Linux appears to have the correct driver already installed.
On the DB9, run a swtich between pins 7 (RTS) and 8 (CTS)
In the FreeDV GUI, Tools > CAT and PTT Config…
Under “PTT in” section:
Select “Enable PTT Input”
Select “CTS = +V”
Choose the Serial device
Thanks
Our thanks to Geoff VK3GTP for contributing this information about FreeDV on Yaesu radios.
Do you have the setup instructions for the Yeasu FT-920? Looking forward to using FreeDV.
Jessie,
Hopefully configuration is similar. Please let us know if you find any non-obvious tips. We look forward to you getting on FreeDV.
Peter
I have a DX-10 and just heard about this. Loaded it up and now can’t find where to change the intial settings for sound card, etc??? Also is there a DX-10 setup doc somewhere? Same as the 991A?
Thanks.
I’m also just getting started. I use the FTdx-10, Windows 11. You might find these setup notes helpful. good Luck! Steve W4GOK
Goal of TX Audio Optimization (FreeDV)
For FreeDV, the goal is not loudness or warmth — it’s:
Zero ALC
Clean, flat audio
No clipping
Stable modem lock at the other end
Minimum IMD
If you do this right, you’ll sound boringly clean — and decode better on marginal paths.
STEP 1 — Lock the Radio Into a “Digital-Clean” TX State
Do this once and leave it alone.
On the FTDX-10:
Setting Value
Mode USB
PROC OFF
Speech Processor OFF
TX EQ FLAT
DNR / NB / Notch OFF
MONI Optional (low level only)
TX Bandwidth Wide (≈ 3 kHz)
ALC Must stay at zero
📌 Rule:
If ALC moves at all, you are overdriving FreeDV.
STEP 2 — FreeDV TX Audio Chain (Critical)
Open FreeDV → Tools → Audio Config
Set these explicitly:
Transmit device → FTDX-10 USB Audio CODEC
Receive device → FTDX-10 USB Audio CODEC
PTT → CAT (already working 👍)
Now go to Tools → Transmit Test Tone
STEP 3 — Set USB Audio TX Level (Most Important Step)
This is the single most important adjustment.
On the FTDX-10:
Menu → USB Audio Input Level
Start low (e.g. 20–30)
While transmitting FreeDV test tone:
Slowly raise USB Audio Input Level
Watch ALC meter
STOP the moment ALC just begins to flicker
Back it off until ALC = 0
🎯 Target:
RF output ≈ 10–25 W
ALC = dead flat
No RF compression behavior
FreeDV does NOT like compression. Zero ALC = clean constellation = better decode.
STEP 4 — Fine-Tune FreeDV’s TX Level (Software Side)
Now adjust FreeDV’s TX Level slider, not the radio.
In FreeDV main window:
Start around -6 dB
Increase slowly until:
RF output is stable
ALC remains zero
No “harshness” on monitor
📌 Never chase more watts — chase clean decode reports.
STEP 5 — Verify with Modem Lock & On-Air Reports
What you want to hear back:
“Very clean”
“Stable decode”
“No artifacts”
“Sounds flat but solid”
What you do NOT want:
Warbling
Metallic breakup
Dropouts when strong
Decode collapsing on peaks
If any of those happen → back down TX level
STEP 6 — Mode-Specific Optimization (Short but Important)
Once TX audio is clean, match mode to conditions:
Mode Use When
700D Weak signals, QRP, marginal paths
700C Slightly better audio, still robust
1600 Good bands, higher fidelity
2020 Very clean path only
💡 Many ops never leave 700D — and that’s perfectly fine.
Optional Advanced Step (Highly Recommended)
Record your own TX audio:
Use a second SDR or WebSDR
Or have a trusted FreeDV op record you
Listen for:
No splatter
No pumping
Consistent syllables
what about older radios
I use a ft847 i sort of had it working but no cat control
Absolutely keen to support a wide range of radios. If you can contribute any tips that would be wonderful.
Hello OM,s
I am looking for settings for FreeDV on Yaesu 857. The software can be started, and Start/Stop Modem also works, but only in 700D, 700E, and 1600 modes. Sending/listening works.
Unfortunately, when I select RADEV1 mode and click on Start Modem, the software closes without any error message or notification.
Do you have any helpful tips?
There was an issue on 2.1 with some PCs where the dependencies (VC++ Runtime, Python) didn’t properly install. Can you try 2.2 (https://github.com/drowe67/freedv-gui/releases/download/v2.2.0/FreeDV-2.2.0-windows-x86_64.exe) and let me know if that works any better?
BTW apologies for not responding sooner, I didn’t receive a notification when you originally posted for some reason.