SunSDR DX2 connection to MixW a guide..

1 June 2026

SunSDR DX — CAT Control with MixW2 & Omnirig | Gazlabs

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SunSDR DX — CAT Control with MixW2 & Omnirig • Setup & Troubleshooting Guide

How It Works

ExpertSDR2 emulates a Kenwood TS-480 via ECATv1 over a virtual COM port pair. Omnirig connects to that port and acts as a CAT broker for MixW2. Audio routes via Virtual Audio Cable (VAC).

ExpertSDR2 (ECATv1) → Virtual COM pair → Omnirig → MixW2

Step 1 — Install a Virtual COM Port Pair

com0com (free) — sourceforge.net/projects/com0com
VSP Manager by K5FR (free) — k5fr.com

Create a pair using low numbers e.g. COM5 ↔ COM6. ExpertSDR2 uses one end; Omnirig the other.

Note: Enable Emulate baud rate in com0com on both ends — without it, idle silence is treated as a dead connection.

Step 2 — Configure ExpertSDR2 (ECATv1)

Options > ECATv1 > tick Enable CAT:

Setting	Value
Virtual COM port	COM5 (first end of pair)
Baud rate	115200
Data / Parity / Stop	8 / None / 1
Rig emulation	Kenwood TS-480

Step 3 — Configure Omnirig

Settings > Rig 1:

Setting	Value
Rig type	Kenwood TS-480
Port	COM6 (second end of pair)
Baud rate	115200
Data / Parity / Stop	8 / None / 1
RTS / DTR	High / High
Poll interval	100 ms (critical — keeps connection alive)
Timeout	4000 ms

Note: 100 ms poll means Omnirig queries the radio constantly, even when idle. Without this the connection drops on inactivity.

Step 4 — Configure MixW2

Configure > TRX/CAT > select Omnirig / Rig 1. MixW2 talks to the radio through Omnirig — no direct COM port needed.

Step 5 — Audio via Virtual Audio Cable

Install VAC from vac.muzychenko.net. Enable the VAC button in ExpertSDR2.

Program	Input	Output
ExpertSDR2	VAC Line 2 (TX from MixW2)	VAC Line 1 (RX to MixW2)
MixW2	VAC Line 1	VAC Line 2

Fixing CAT Drops on Inactivity

Drops when you stop tuning or change focus? Idle timeout somewhere in the chain. Work through these:

Fix	Action
1 Omnirig poll 100 ms	Set poll interval to 100 ms. Keeps traffic flowing so port never goes idle.
2 Windows USB power	Device Manager > Ports > right-click COM port > Power Management > uncheck allow sleep. Repeat for USB Root Hubs. Set Power Plan to High Performance.
3 com0com baud rate	Tick Emulate baud rate on both ends of the virtual pair.
4 Omnirig timeout	Set timeout to 4000 ms.
5 Switch to TCI/SDC	Replace ECATv1 with TCI via SDC. Most stable fix — see section below.
6 Update ExpertSDR2	Older versions had CAT bugs. Get latest from expertelectronics.ru.
7 Low COM numbers	Keep ports below COM10 — high numbers cause issues in some software.

Tip: If fixes 1–4 don’t solve it, go straight to TCI/SDC (Fix 5). It’s the only method confirmed fully stable by SunSDR DX users.

Advanced: Stable Connection via TCI and SDC

What is TCI? TCI (Transceiver Control Interface) is Expert Electronics’ native protocol for ExpertSDR2. It runs over a WebSocket on localhost — not a serial port emulation. Persistent, fast, doesn’t go idle.

SDC bridges TCI to a virtual COM port so Omnirig connects normally. ECATv1 is removed from the chain.

ExpertSDR2 (TCI/WebSocket) → SDC → Virtual COM → Omnirig → MixW2

Real-world fix: Customer tried every method — all dropped. Switched to TCI/SDC — instant stable connection. Catch: RIG Emulator was missing in SDC because the version was too old. Fix: find the cumulative update on the UT4LW site, get a reg key, update. Working version: SDC v19.06 x64.

Step A — Enable TCI in ExpertSDR2

Options > TCI > tick enable:

Setting	Value
Enable TCI	Tick
Port	50001 (default)
Address	localhost / 127.0.0.1

Step B — Install SDC (version matters)

Download from UT4LW website. If RIG Emulator is missing, the version is too old.

Note: Get the cumulative update — requires a registration key. Confirmed working: SDC v19.06 x64.

Add TCI Client → address: localhost, port: 50001
Add RIG Emulator output → assign to COM7

Step C — Point Omnirig at SDC

Change Omnirig port from COM6 to COM7 (the SDC RIG Emulator). All other settings stay the same.

Note: ECATv1 and TCI can run together in ExpertSDR2. Test SDC alongside your existing setup before switching fully.

Quick Reference

Standard (ECATv1):

Software	Port	Role
ExpertSDR2 ECATv1	COM5	CAT out (TS-480 emulation)
Omnirig Rig 1	COM6	CAT in (100 ms poll)
MixW2	Omnirig	Via Omnirig Rig 1
ExpertSDR2 VAC	VAC Line 1	RX audio to MixW2
MixW2 audio out	VAC Line 2	TX audio to ExpertSDR2

Stable (TCI + SDC v19.06 x64):

Software	Port / Address	Role
ExpertSDR2 TCI	localhost:50001	TCI WebSocket server
SDC TCI Client	localhost:50001	Connects to ExpertSDR2
SDC RIG Emulator	COM7	Virtual CAT port for Omnirig
Omnirig Rig 1	COM7	CAT in (100 ms poll)
MixW2	Omnirig	Via Omnirig Rig 1
ExpertSDR2 VAC	VAC Line 1	RX audio to MixW2
MixW2 audio out	VAC Line 2	TX audio to ExpertSDR2