Setting up the Yaesu FTX-1 for VARA HF over a single USB cable requires proper configuration of digital audio passbands and Push-To-Talk (PTT). Using software-based CAT PTT avoids the frequent conflicts and handshake issues associated with hardware RTS/DTR lines on both macOS and Windows.

1. Radio Settings (Yaesu FTX-1)

Set the radio operating mode to DATA-U (Data Upper Sideband).

Access the radio menu and configure the following parameters to ensure full bandwidth audio pass-through:

• MOD SOURCE (DATA IN SELECT): USB (Routes TX audio from the USB codec)
• DATA LCUT FREQ: OFF (Allows VARA low-frequency tones through)
• DATA HCUT FREQ: OFF (Disables the high-cut filter for maximum passband width)

Note: Because this configuration utilizes software CAT commands for PTT, the radio’s hardware RPTT SELECT parameter is bypassed.

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2. macOS Setup (Native Path via MacWinlink)

Mac users can run VARA HF sessions directly without virtual machines or complex Wine wrappers by using MacWinlink.

USB Driver & Serial Ports

1. Ensure the Silicon Labs CP2105 dual USB-to-UART driver is active.
2. The FTX-1 exposes two serial device nodes on macOS:
   • Enhanced Port: Used for CAT commands (e.g., /dev/cu.SLAB_USBtoUART or /dev/cu.usbserial-...1).
   • Standard Port: Used for auxiliary functions (not required for CAT PTT).

Audio & Session Configuration in MacWinlink

• Audio Input / Output: Select the USB Audio CODEC devices.
• Rig Model: FT-710 or FTDX10 (if the FTX-1 profile is not listed, as they share the same modern Yaesu CAT command set).
• Serial Port: Select the Enhanced /dev/cu.* port.
• Baud Rate: 38400
• PTT Mode: CAT

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3. Windows Setup (Winlink Express)

If operating on a Windows machine:

Soundcard Settings

• Playback / Output Device: Speakers (USB Audio CODEC)
• Recording / Input Device: Microphone (USB Audio CODEC)
• Receive Level: On a quiet frequency with background noise only, adjust the Windows input volume until the VU meter in VARA HF sits comfortably in the green zone (~12 o’clock).

Winlink Express Radio Setup

In the Winlink VARA HF Session, go to Settings > Radio Setup:

• Radio Model: FT-710 or FT-DX10
• Radio Control Port: Select the Enhanced COM Port (check Windows Device Manager under Silicon Labs CP210x).
• Baud Rate: 38400
• PTT Port (Optional): Select the Radio Model (e.g., FT-710) from the dropdown list. (Do NOT select a COM port here).
• Enable RTS: Unchecked
• Enable DTR: Unchecked

Why this works: Selecting the radio model as the PTT Port instructs Winlink to send native CAT transmit commands across the existing serial stream, bypassing hardware RTS/DTR voltage signaling.

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4. Transmit Audio (Drive Level & ALC)

VARA HF requires high linearity. Overdriving the transmitter causes ALC compression, which distorts OFDM subcarriers and reduces throughput.

1. Set the FTX-1 display meter to monitor ALC.
2. Click the red Tune button in the VARA HF modem window.
3. Adjust the Drive Level slider in VARA HF (a setting around -8 dB is a reliable starting point).
4. Target: The ALC meter on the radio should show minimal deflection (staying within the lower third of the scale / 1–2 bars max).

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Troubleshooting: The Missing VARA PTT Menu Trap

• The Problem: The “PTT” configuration option inside the VARA HF modem menu is missing or disabled.
• The Cause: When VARA is launched via Winlink / MacWinlink, the host application takes exclusive control of PTT orchestration and hides VARA’s internal PTT menu to prevent timing collisions.
• The Solution: Configure all PTT and CAT routing within the Winlink / MacWinlink Radio Setup menu, not within the standalone VARA window.