Setting up the Yaesu FTX-1 for VARA HF over a single USB cable can be tricky, especially when configuring the Push-To-Talk (PTT). This guide covers my tested and working configuration using CAT PTT, bypassing the often-problematic hardware RTS COM port triggers.

1. Radio Settings (Yaesu FTX-1)

First, ensure your radio is operating in DATA-U (Data Upper Sideband) mode.

Access the radio’s menu and configure the following parameters to ensure wide-bandwidth audio routing:

• MOD SOURCE (DATA IN SELECT): USB (Routes audio input from the PC)
• DATA LCUT FREQ: OFF (Allows VARA’s wide tones through)
• DATA HCUT FREQ: OFF (Disables the high-cut filter for maximum bandwidth)

Note: Because this setup utilizes software-based CAT PTT, the radio’s RPTT SELECT setting is bypassed and does not matter.

2. PC Soundcard Settings

The single Yaesu USB cable creates a virtual soundcard for audio routing.

• Playback/Output Device: Speakers (USB Audio Codec)
• Recording/Input Device: Microphone (USB Audio Codec)
• Receive Audio Calibration: Tune the radio to a clear frequency with pure static. Open the Windows Sound settings and adjust the input volume for the USB Audio Codec until the VU meter in the VARA HF modem window sits directly in the green zone (roughly 12 o’clock).

3. Winlink Express Radio Setup

When launching a VARA HF session through Winlink Express, Winlink takes exclusive control of the PTT routing and hides the internal PTT menu inside the VARA software.

In the Winlink session window, navigate to Settings > Radio Setup and configure it exactly as follows:

• Radio Model: FT-710 or FT-DX10 (Select these if the FTX-1 is not explicitly listed, as they share the identical CAT command architecture)
• Radio Control Port: Select your Enhanced COM Port (Check Windows Device Manager under Silicon Labs CP210x to verify your specific COM number)
• Baud Rate: 38400
• PTT Port (Optional): Select the Radio Model (e.g., FT-710) from the drop-down list. Crucial: Do NOT select a COM port here.
• Enable RTS: Unchecked
• Enable DTR: Unchecked

Why this works: By selecting the radio model for the PTT Port instead of a Standard COM Port, Winlink sends a digital transmit command over the existing, proven CAT connection, completely avoiding hardware voltage requirements.

4. Transmit Audio (Drive Level)

VARA HF requires a clean, undistorted signal. If the radio is overdriven, gateways will fail to decode the transmission.

1. Set the FTX-1 display to monitor the ALC meter.
2. Click the red Tune button in the VARA HF modem window to transmit a steady test tone.
3. Adjust the Drive Level slider on the left side of the VARA HF window. A setting around -8 is a highly effective baseline.
4. Verify that the ALC meter on the radio just barely flickers off zero. It must remain in the bottom third of the scale to prevent distortion.

Troubleshooting: The Missing VARA PTT Menu Trap

The Problem: You read a guide online telling you to open VARA HF, go to Settings, and click “PTT.” But when you look at your VARA HF menu, the PTT option is completely missing—you only see “VARA Setup,” “SoundCard,” and “Waterfall.”

The Cause: Winlink Express and VARA HF are two separate programs running simultaneously. When you launch a VARA HF session through Winlink, Winlink intentionally hides VARA’s internal PTT menu. It does this because Winlink requires exclusive control over keying your radio to coordinate the data bursts.

The Solution: Stop looking for the PTT settings inside the black VARA HF modem window. Instead:

1. Go back to your Winlink Express Session window.
2. Click Settings > Radio Setup.
3. Configure your PTT routing directly inside Winlink (using the CAT PTT method outlined in Step 3 above).

Winlink will seamlessly handle sending the transmit command to your radio whenever the VARA modem needs to send data.