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Yaesu FT-991A

The FT-991A is all mode, all band MF/HF/VHF/UHF transceiver with C4FM (System Fusion) Digital capability. The FT-991A includes multi-mode operation on CW, AM, FM, SSB, and Digital Modes (Packet, PSK31, RTTY and C4FM), with 100 Watts of HF/50mhz Capability (50 Watts VHF/UHF).

The has a high-resolution full color 3.5“ TFT touch panel, incorporating a High Speed Spectrum and High Resolution real-time scope.

The FT-991 can be connected to a computer using a USB cable for CAT control and firmware updates, or the use of an integrated SCU-17 Interface Unit to support USB Audio In/Out, TX Control (PTT, Key, Shift).

The FT-991A has an in-built automatic antenna tuner.

TNC cable

(taken from FT-450D manual)

Pin Use NinoTNC / Kantronics pin
1 TX audio 1
2 Ground 6
3 PTT 3
5 RX audio 5

A suitable cable can be made from a PS/2 extension lead, scrap PS/2 mouse or keyboard. Sometimes with the mouse/keyboard option, not all of the required pins are populated, so may not be suitable. Identify the pins with a multimeter (a croc clip lead is useful here.) Solder a DB9 plug on to the other end as above.

Packet Radio with NinoTNC

Settings on the radio for HF are:

  • mode: data-usb
  • dial setting of 7.04575 (for GB7IOW)

On the (F) button:

  • DT Gain 10 (DT Gain is unique to each setup, monitor ALC - increase until you see ALC kicking in, then back off)

On the Menu button:

  • 073 Data Out Level at 80-95
  • 062 Data Mode - OTHERS
  • Remember to set 108/109 back to DAKY/DATA if you've been using the SCU.

For legacy HF modes with a 1700 CF (Centre Frequency)

  • Menu 064 and 065 set at 1700Hz. (F) Width 500hz

For the new beta NinoTNC modes with a 1500 CF (500Hz Bandwidth)

  • Menu 064 and 065 set at 1500Hz. (F) Width 800hz (500Hz does work though)

Packet Radio with soundcard modem

The FT-991A’s USB interface can be used for packet radio with soundcard modem software, with the caveat that it cannot be used for 9600 baud. See

radios/ft-991a.txt · Last modified: 2024/03/26 23:04 by mm0rfn