VFO-Knobby RF.GuruVFO-Knob is a 66 mm touch-screen tuning knob for AetherSDR, the free, open-source app for FlexRadio transceivers. Tune, pick the step, key the transmitter and watch the S-meter — over one USB-C cable or over WiFi. The firmware is already on it, and versions for more radios and apps are on the way.
Receive and transmit, shown to scale in the 66 mm body. The readouts follow the bars — just as they do on the knob.
It isn't polling — it's told. VFO-Knob speaks TCI v2.0, the open control protocol built into AetherSDR. Tune at the desktop and the knob follows; turn the knob and the desktop moves.
Tune, key, listen and read the meters without looking for the mouse.
Tap a digit to set the step to that decade. Acceleration rides on top: a flick crosses a band, a slow turn lands on 10 Hz.
Tap to key, tap along the bottom to unkey. A transmit time-out, a haptic nudge every 10 seconds and a screen that goes amber with a red PTT bar keep you aware you're on the air.
An S-meter on receive. SWR and auto-ranging forward power — up to 2 kW full scale — on transmit, with the mic level riding inside the power arc.
Receive audio from the 3.5 mm jack, transmit audio from the built-in microphone, each with its own level.
Tap to open, turn to choose, tap anywhere to accept. No menus to dig through.
Tap the meter arc and the knob shows its network addresses — no digging through your router to find it.
A configuration page on the knob itself: status, AetherSDR host, WiFi, audio levels, transmit time-out, password and updates.
Every firmware image is RSA-3072 signed and checked before it's accepted — and a failed update rolls back by itself.
Both arrive with the firmware installed and do everything on this page. The difference is how they're powered — and so where they like to live.
Cordless, on your WiFi
A built-in battery means no cable on the desk. Set up your WiFi once over USB-C, then put the knob wherever your hand falls — beside the keyboard or at the operating position — and it reaches AetherSDR cordless.
€99
Firmware preinstalled
One USB-C cable for power and data
Plug it into the computer running AetherSDR: it shows up as a network adapter, gets its address by itself and connects — no WiFi to set up. Want it cordless? Run it from a power bank and it goes over WiFi instead.
€99
Firmware preinstalled
| Feature | Blue | Black |
|---|---|---|
| Price | €99 | €99 |
| Power | Built-in battery, charges over USB-C | USB-C — computer, charger or power bank |
| USB-C link to the computer | Yes | Yes |
| WiFi | Cordless, on battery | From a power bank or charger |
| Display, knob, haptics, audio | Yes | Yes |
| Windows · macOS · Linux | Yes | Yes |
| Firmware preinstalled | Yes | Yes |
€99 either way, firmware preinstalled. Plug it in, turn on TCI in AetherSDR and follow the setup below.
The knob chooses for itself: the cable whenever there's a computer on the other end of it, WiFi when it runs from a battery, charger or power bank.
One cable for power and data
The knob shows up on your computer as a USB network adapter, gives it an address and talks TCI over the cable. No WiFi and no IP addresses to type in: it connects to AetherSDR on the computer it's plugged into.
Anywhere on your network
Enter your network and the AetherSDR computer's address once, on the knob's configuration page. From then on it connects by itself whenever it isn't plugged into a computer — cordless on the blue edition's battery, or from a power bank or charger on the black.
AetherSDR is the free, open-source, native amateur-radio workstation for FlexRadio 6000, 8000 and Aurora transceivers. VFO-Knob talks to it directly through its built-in TCI v2.0 server — no plug-ins, no bridge software, no virtual serial ports.
AetherSDR runs natively on Windows, macOS and Linux — and so does the knob, over USB-C or WiFi on all three.
AetherSDR is where VFO-Knob starts. Versions for other radios and SDR apps are in the works.
The firmware is already on the knob. Four steps — and the last one is optional.
Install AetherSDR — free for Windows, macOS and Linux — and enable its TCI server: the TCI panel in the button bar.
Connect the knob to the computer running AetherSDR with a USB-C cable and give it about ten seconds. The socket only works one way round: if no network adapter appears, turn the plug over.
Browse to http://10.55.42.1, sign in with admin / admin, and set your own password — the knob can key a transmitter.
Add your WiFi network and the AetherSDR computer's address, then run the knob from its battery or a power bank.
Binds the knob by itself — no driver to install.
If your firewall drops incoming connections (ufw, or firewalld's public zone), let the knob reach AetherSDR's TCI port once:
$ sudo ufw allow proto tcp from 10.55.42.1 to any port 50001Same four steps: plug the knob in, open http://10.55.42.1 and it connects to AetherSDR on that Mac.
Rather keep the Mac's ports free? Set up WiFi once and run the knob cordless.
Windows 10 (1903 or later) and 11 load the knob's network driver by themselves. Windows files the link as a public network, though, so allow AetherSDR's TCI port on it once.
A USB-SERIAL CH340 port in Device Manager means the plug is upside down: turn it over.
Step-by-step Windows guideLatest firmware: v1.3.2
Firmware images are RSA-3072 signed and verified before they're accepted. On WiFi the knob checks once a day while it's on and installs quietly — it never reboots on its own; the new image waits until you next restart it. Over USB, the configuration page fetches the update and hands it over. If a new image ever fails to boot, the knob rolls back to the one before.
PTT is a toggle, so the radio stays keyed when you let go. That's why there's a transmit time-out, a haptic reminder every 10 seconds and a screen that goes amber with a red PTT bar. If something goes wrong, the knob steps down in stages — unkey, close the connection, tear it down, and finally restart itself. AetherSDR unkeys as soon as it sees the connection close.
Safety notesApache-2.0
Read it, build it, change it. The source, the build instructions and the full setup guide live on GitHub.
Which edition, your station, your operating system — ask the RF.Guru team and we'll help you get tuning.
