VFO-Knobby RF.Guru
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New: Bluetooth headsets & speakersNew: OpenWebRX & WebSDR
AetherSDR · FlexRadio · Icom · OpenX6X00 · SVXConnect · Telephone · UberSDR · Kiwi888 · OpenWebRX · WebSDR · ADS-B Radar · Clock · Weather · JupiterSDR (beta) · EpiBeam (beta)

Tune your radio with a real knob

VFO-Knob is a 66 mm touch-screen tuning knob for AetherSDR — the free, open-source app for FlexRadio transceivers — for FlexRadio itself, and for Icom's IC-705, IC-7610, IC-9700, IC-7300MK2 and IC-R8600, and for Xiegu's X6100 and X6200 on OpenX6X00 — and, in beta, for Zeus SDR — with more radios on the way. Or, with no radio at all, a dial for UberSDR, KiwiSDR, Web-888, OpenWebRX and WebSDR web receivers, a talkgroup knob for SvxLink reflectors, or a telephone. Turn the metal ring to tune; tap the screen to pick the step, key the transmitter and more — over one USB-C cable or cordless on its battery. Pick your radio's firmware on the knob itself.

Order yours · €99See it in actionMade for …
Works onWindowsmacOSLinux
VFO-Knob with the IC-705 firmware, in Icom's black and blueVFO-Knob with the AetherSDR firmware, showing 3.630.00 MHz LSB on 80 m with the S-meter at S9+40
New

Your headset is the station.

The knob now speaks Bluetooth. Pair a headset and you hear the radio in it, talk through its boom microphone, and key with its call button — or just by lowering the boom. Or pair a speaker and fill the room. No cable to the knob, no hand mic, both hands free for the log.

  • Its microphone is the one on the air. The headset's boom mic transmits and the knob's own goes quiet. Wideband speech where the headset has it.

  • The call button is a PTT too. Press to key, press again to unkey — beside the knob's own PTT, which keys as always. Muted? It won't key a dead carrier: the knob clicks three times and says HEADSET MUTED.

  • Or the boom arm. On a headset that mutes when the boom goes up — the Jabras do — lower the boom to talk, raise it to stop. Never by itself: it waits for the boom to have been up once.

  • Safe when it walks away. Out of reach or out of battery while you transmit, and the knob unkeys by itself. A tap on the knob always stops a transmission too.

  • Or a Bluetooth speaker. A speaker plays the knob's audio, its volume following the knob's VOLUME on speakers that take it. You talk into the knob's own microphone, and the speaker falls silent while you transmit.

  • Its battery at a glance. A headset or speaker that reports its charge — most made for iPhones do — shows a green, yellow or red battery beside its logo, and its charge on the configuration page.

  • Paired once, there every time. Pair it on the knob's configuration page; the knob tells a speaker from a headset by itself, calls it whenever it switches on, as your phone does — and keeps a level for each, -24 to +12 dB, so a quieter speaker is simply raised. The page lists the last eight: from a speaker to a headset and back is Connect beside it, no pairing mode.

  • Every firmware with sound. Icom, FlexRadio, AetherSDR, JupiterSDR and SVXConnect: listen and talk. Telephone: your calls, in a headset or on a speaker. UberSDR: listen. Clock: its alarms ring in it.

Order · €99Read the headset guide →
Jabra Evolve2 65 Mono: a one-ear headset with a boom microphone
Jabra Evolve2 65 Mono
Jabra Evolve2 65 Stereo: a two-ear headset with a boom microphone
Jabra Evolve2 65 Stereo
JLab Pop Party: a small Bluetooth speaker with a carry strap and a lit rim
JLab Pop Party
Sony SRS-XB100: a small cylindrical Bluetooth speaker with a strap loop
Sony SRS-XB100

Headsets made with the Jabra Evolve2 65, Mono or Stereo; speakers with the JLab Pop Party, the Sony SRS-XB100 and the Marshall Stockwell III.

A Marshall Stockwell III Bluetooth speaker with the VFO-Knob in front of it, tuned to 14.215.00 USB
Our pick

Shape the band on the speaker itself.

Our favourite speaker for the knob is the Marshall Stockwell III: it has its own bass and treble controls, right on top. Turn the treble down to take the hiss off a weak HF signal, the bass up to give a ragchew some body — the receiver's audio shaped by hand, the way a station speaker should be.

Paired with the knob, it is a speaker by itself, the quickest of those we tried — a seventh of a second behind the jack — with the knob's VOLUME for its own and your bass and treble on top.

A headset connected: its name and its microphone where PTT isOn the air through the headsetRAISE BOOM: the boom arm as the PTT, and down

Turn the ring. Touch the screen.

The metal ring around the screen is the tuning dial — turn it and the frequency follows. Everything else is a tap away.

VFO-Knob from the side: the blue ring turns around the round screen; on the black base, the USB-C port and the 3.5 mm jack
  1. 1

    The ring. A CNC-machined metal ring that turns around the screen: the VFO dial, and the control for every list you open.

  2. 2

    The touch screen. 1.8″ round, 360 × 360, bright and sharp — its brightness yours to set, a screensaver when it is left alone, and turned the other way up for a mount with the cable at the bottom. Tap a digit for the step; tap mode, filter, RIT, AGC or gain to change it; tap the bottom for PTT.

  3. 3

    Haptics. A vibration motor gives the controls a feel — and stays silent while you transmit.

  4. 4

    Microphone and 3.5 mm jack. A built-in microphone for your voice; receive audio to an earpiece, headphones or a speaker.

  5. 5

    USB-C. One cable for power and data — the knob shows up on your computer as a network adapter, and it charges the battery.

  6. 6

    The battery. Unplugged, the knob runs on its own battery and shows its charge at the top of every face — green, yellow, then red — and as a percentage on its address card.

Your radio, at your fingertips

Receive and transmit in the AetherSDR theme, shown to scale in the 66 mm body. The readouts follow the bars — just as they do on the knob. Every radio's firmware has its own theme: the IC-705 wears Icom's black and blue.

AetherSDR theme, receiving: the S-meter rises to S9+20 and falls back while its readout follows and the 100 Hz digit ticks
Receive. S-meter, band, mode and filter, the frequency with its tuning digit underlined, step, RIT, volume and mic gain.
AetherSDR theme, transmitting: SWR on the left, forward power on the right with the mic level inside it, both readouts following their bars; red PTT bar
Transmit. SWR on the left, forward power on the right with the mic level inside it — and a red PTT bar you can't miss.

It isn't polling — it's told. With AetherSDR, 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.

Everything you reach for, under one hand

Tune, key, listen and read the meters without looking for the mouse.

The ring is the dial

The whole machined metal ring around the screen turns — that's your VFO. Acceleration rides on top: a flick crosses a band, a slow turn lands on 10 Hz.

Tune by the digit

Tap a digit of the frequency and the ring tunes in that decade — from 10 Hz up to MHz. Fixed-width digits that hold still as they change, the active one underlined.

PTT with guard rails

Tap to key — it keys as your finger lifts, so a swipe never does — and tap along the bottom to unkey. On the air the screen changes colour behind a red PTT bar.

Quiet on the air

Nothing vibrates while you transmit: the motor sits beside the microphone and would be heard. You feel the unkey once the radio is back on receive.

Real meters

S-meter on receive; SWR, forward power auto-ranging to 2.5 kW and mic level on transmit — each holding its peak for a second, so SSB reads as speech, not flicker.

Audio both ways

Receive audio from the 3.5 mm jack, transmit audio from the built-in microphone — or both through a Bluetooth headset. Clear, natural speech, just right for ham radio. Wired earphones too quiet at full volume? The jack goes up to 12 dB above it.

Mode, filter, RIT

Tap to open, turn the ring to choose. Filter and RIT change as you turn; band and mode take a tap on their panel. No menus to dig through.

AGC and gain

Either side of the S-meter reading, set the same way: AGC on the left, the front end's gain on the right — P.AMP on the IC-705.

A second receiver

On the Icom, FlexRadio and UberSDR firmwares, a web SDR plays beside what you tune and follows it: one in each ear.

Addresses at a long press

Long-press the meter arc and the knob shows its network addresses — no digging through your router to find it.

Your radio in a browser

Open vfo-knob.local on a phone or computer: the radio's controls, the knob's settings and firmware — and a JSON API for your logbook.

Updates on the dial

On WiFi the knob asks on the screen when there's a new release: one tap installs it. Never while you transmit, never unasked — and every image is signed.

A screensaver

New

Left alone for a minute, every firmware shows a screensaver — Matrix rain, an analog or a digital clock, or the frequency drifting round the glass — dims it a minute later and goes dark a minute after that, each time yours to set. The first turn or touch only brings the dial back; the next one tunes. The Clock and the Weather, screens to look at, stay lit until you set one.

The screensaver guide →

Settings that survive a power cut

New

Every firmware keeps its settings on the knob's built-in SD card, in a folder of their own — the radios and their logins, the receivers, the levels, the page's password, SVXConnect's key and certificate, the telephone, the SmartLink and Google sign-ins. Each in three copies, written in turn and read back, so a power cut never loads half-written settings, and a switch to another firmware and back finds each one's as they were. Your WiFi networks and Bluetooth devices stay in the knob itself.

The SD card, in the setup guide →

Swipe for more

Tap and turn do most of it. A swipe or a hold reaches the rest — each radio's firmware puts its own extras there.

Swipe down

What you listen to

RX: the radio alone or a web SDR beside it. Then MAIN/SUB and the antenna on the IC-7610, the antenna on the IC-R8600, V/M for the memories on the IC-705 and IC-9700, RX ANT, TX ANT and V/M on a FlexRadio. On the Telephone: the keypad.

Icom · FlexRadio · UberSDR · Telephone

Swipe up

Another radio

Up to four per firmware — an IC-705, an IC-7610, an IC-9700 and an IC-R8600; two FlexRadios; AetherSDR on two computers, four UberSDRs. Turn to one, tap, and the knob restarts into it — on Kiwi888, four receivers switch live, with no restart.

Every radio firmware

Swipe from the left

Balance, RF gain, power

BALANCE between the radio and the web SDR, while one plays; then RF GAIN, and POWER in watts on the Icoms. All apply as the ring turns.

Icom · FlexRadio · UberSDR

Swipe from the right

Tuner, squelch, SSTV

The IC-7610's tuner in or out of line — nothing transmitted. The IC-R8600's squelch. On a FlexRadio: TUNE, ATU and the tuner's memories. On an UberSDR: its SSTV gallery.

IC-7610 · IC-R8600 · FlexRadio · UberSDR

Tap or hold the PTT bar

Key, or choose the antenna

A tap keys as your finger lifts, so a swipe that starts on the bar never does. On a FlexRadio, the IC-7610 and the IC-R8600, a press held half a second opens the antennas instead, with a buzz — and keys nothing.

Every firmware that transmits · antennas: FlexRadio, IC-7610, IC-R8600

Hold the S-meter

Addresses, then the picker

Hold until the knob clicks: its firmware and version, its power — battery 85 % or on USB power — and its network addresses. Hold again until it buzzes for the firmware picker.

Every firmware · on EpiBeam and ADS-B Radar, the gear · on the Clock and the Weather, a tap

Your radio in a browser

Every firmware serves a page of its own. Open vfo-knob.local on your phone or computer and, with the radio connected, it opens on the radio's controls — in the knob's own colours.

The knob's web page for an IC-7610: 7.126.000 MHz LSB at S8, a frequency field with steps from 10 Hz to 100 kHz, and buttons for band, mode, filter, AGC and preamp

Everything the knob can set

  • Frequency, typed or stepped
  • Band, mode and filter
  • AGC, preamp or RF gain
  • Power and the tuner
  • MAIN/SUB, antenna and RIT
  • The web SDR and its balance
  • Which radio is in use
  • The knob's volume and mic gain

Nothing on the page transmits. Config leads to the knob's own settings — WiFi, audio, the screen, password, firmware — with the radio staying connected.

For your logbook and other programs

The same, as JSON: a logging program on your phone or computer reads the frequency and mode for each QSO, and anything can set them with a URL.

GET http://vfo-knob.local/api/radio
GET http://vfo-knob.local/api/radio/set?freq=14074000&mode=usb

Also filter, agc, rfgain, power, tuner, rx (main/sub), ant, rit, sdr and balance; /api/radios lists the radios and switches between them, and /api/status gives the knob's own state, its battery too, and /api/screenshot a picture of its face as it is drawn. All need the page's login, and no setting is taken while the radio is on the air. Over WiFi the page first asks for a password of the knob's own, 8 to 32 characters; until it has one, the API answers only /api/status and /api/config.

A second receiver, anywhere

On the Icom, FlexRadio and UberSDR firmwares, a KiwiSDR, Web-888 or UberSDR plays beside what you tune and follows it. Hear the band from your shack in one ear and from across the country in the other.

RX chooser on the knob: Web-888, turn to choose, tap to accept
The Icom face with a web SDR playing: its S-meter a thin blue line outside the radio's, S5 in blue under the radio's S7
BALANCE on the knob: L | R, turn from RADIO to SDR

  • It follows the radio. Frequency, mode and passband, retuned as the ring turns — a second receiver somewhere else, on the same signal.

  • Radio left, SDR right. Both brought to the same loudness; BALANCE fades from one to the other. The SDR goes quiet while you transmit.

  • Up to four receivers. A KiwiSDR, Web-888, or UberSDR through its Kiwi input — over https too, behind the kiwisdr.com proxy or Cloudflare — each with a Test on the configuration page that says whether it will let you in.

  • The owner's limits kept. A receiver whose owner keeps its channels for browsers is tried once and left alone; a busy or time-limited one is waited for, not hammered.

Your radio, your firmware

Every radio gets its own firmware, with its own theme — so which radio a knob is for shows at a glance. Pick yours on the knob when you first start it, and switch to any other whenever you like — no computer needed.

VFO-Knob with the IC-705 firmware: Icom's black and blue face, showing 145.500.00 MHz FM on 2 m at S9+20

The knob with the IC-705 firmware, in Icom's theme

  • AetherSDR

    FlexRadio 6000, 8000 and Aurora through AetherSDR, on Windows, macOS and Linux.

    USB-CWiFi
  • FlexRadio

    FLEX-6000 and 8000 directly, as a MultiFlex station — on your LAN or through SmartLink.

    WiFi
  • Icom

    Straight to the radio over its own network — no computer in between.

    • IC-705
    • IC-7610
    • IC-9700
    • IC-R8600 · receiver
    • IC-7300MK2
    • IC-7760 · beta
    • IC-905 · beta
    WiFi
  • OpenX6X00New

    A Xiegu X6100 or X6200 on OpenX6X00, their open firmware — over the radio's own TCI, no computer.

    • X6100
    • X6200
    WiFi
  • JupiterSDRBeta

    A client for Zeus SDR, over its TCI: tune, key and listen. Help wanted with testing.

    WiFi
  • Telephone

    No radio needed: a telephone on your SIP account, your favourites on the ring.

    WiFi
  • SVXConnect

    No radio needed: a talkgroup node on an SvxLink reflector.

    WiFi
  • EpiBeamBeta

    The beam switch for a phased array — a 4-square or 8 directions — for EpiCenter, the station's master. Its link to EpiCenter is still to come.

  • ADS-B RadarNew

    No radio needed: a radar of the aircraft round you, from adsb.fi, adsb.lol, airplanes.live or your own receiver — the range on the dial, a tap for an aircraft's route.

    WiFi
  • ClockNew

    No radio needed: a clock for the shack — local time on the hands, UTC on a 24-hour ring, four faces on the dial, ten alarms.

    WiFi
  • WeatherNew

    No radio needed: a weather station for one place, from Open-Meteo's forecast — now, the next 24 hours, the next 5 days.

    WiFi

In the pipeline: OpenHPSDR (Hermes Lite 2, ANAN).

Your IC-705, from the easy chair

The built-in microphone is made for ham radio: clear, natural speech on the air, no headset or hand mic needed. Plug an earpiece into the 3.5 mm jack — or pair a Bluetooth headset — and the knob is a complete remote for your IC-705 over WiFi — tune, key, talk and listen from the easy chair, the garden or the kitchen table, with no computer in between.

Older radios, through a bridge

We want the knob on as many radios as we can. For radios without a network port — like the original IC-7300 — a Raspberry Pi interface is coming: it hooks to the radio's USB port and puts it on your network for the knob. First up are radios whose USB port carries both CAT and audio.

No radio? Tune the world's receivers

Four firmwares make the knob the dial of a web SDR — a receiver someone shares on the internet, or one on your own network. No radio, no computer: give the knob a receiver's address, turn the ring and listen.

  • UberSDRReceive only

    A dial for an UberSDR web receiver — spots, voices and SSTV.

    WiFi
  • Kiwi888Receive only

    A dial for KiwiSDR and Web-888 receivers — four antennas a swipe apart.

    WiFi
  • OpenWebRXNewReceive only

    A dial for OpenWebRX and OpenWebRX+ receivers — up to four, BAND from the receiver's own list.

    WiFi
  • WebSDRNewReceive only

    A dial for PA3FWM's WebSDRs on websdr.org — Twente's wide-band one and the many others.

    WiFi

Beside a radio: on the Icom and FlexRadio firmwares a KiwiSDR, Web-888 or UberSDR plays in your right ear — a second receiver, anywhere.

VFO-Knob with the UberSDR firmware: S9+10 on 20 m, 14.215.00 USB, the spot LU7YZ on the slabVFO-Knob with the Kiwi888 firmware: S9+10 on 20 m, 14.200.00 USB, the receiver EchoTracer, a Web-888 at Lombardsijde

One knob. Every radio.

One model, with a battery, for every firmware there is — and every one still to come: the knob's picker loads the list fresh each time. Nothing to choose when you order: you pick your radio on the knob itself, and switch whenever you like.

VFO-Knob: a blue knob with a round display, on a black base with a USB-C port and a 3.5 mm jack

VFO-Knob

On the cable at your desk, or cordless on its battery

Plugged into the computer it runs from one USB-C cable, always on next to your keyboard, and charges as it goes. Unplug it and it carries on over your WiFi — to the couch, the operating position or wherever your hand falls.

  • Built-in rechargeable battery — cordless on your WiFi
  • USB-C for power and data — always on at your desk, and it charges
  • Firmware picker: choose your radio on the knob — every firmware is on its microSD card, new ones arrive as they're released
  • Every firmware's settings on that card too, three copies deep — a power cut never loads them half-written

€99

Every firmware included

Order from the RF.Guru shop

Two ways to connect

The knob chooses as it starts: the cable when there's a computer on the other end of it, WiFi otherwise — on its battery, a charger or a power bank. Started on its battery, it stays on WiFi when you plug it in, until you Reboot it from its page.

USB-C

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.

WiFi

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 its battery. It remembers up to four networks — home, the club, your phone's hotspot — and where none of them reaches, it opens its own hotspot so your phone can add one.

VFO-Knob with the AetherSDR firmware, angled, showing the tuning display

Made for AetherSDR

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.

Windows
macOS
Linux
Order · €99Get AetherSDR

Read the AetherSDR guide →

VFO-Knob with the multiflex firmware, in the Maestro's blue: S9+20 on 20 m, 14.200.00 USB, 2700 Hz filter, AGC MED and RF.G +8 dB

Made for FlexRadio

With the multiflex firmware the knob talks to a FLEX-6000 or FLEX-8000 itself, over the radio's own API on your network — no SmartSDR, no AetherSDR, no computer. It's one of the radio's MultiFlex stations, in the Maestro's colours. At start-up it asks on the screen what to be:

A remote transceiver of its own

Its own slice, its own transmit settings, and receive and transmit audio as Opus over WiFi — the jack and the built-in microphone are the station. SmartSDR, AetherSDR or a Maestro can stay on the radio beside it.

The dial and PTT for a station

Like a FlexControl, for a SmartSDR, AetherSDR or Maestro station already on the radio: the knob tunes that station's active slice and follows when you click another, and PTT keys it with that station's microphone.

  • At home or away. On your LAN — where the knob finds the radio by itself — or through SmartLink with your FlexRadio account: the radio a continent away, Opus audio and PTT included.

  • Everything on the ring. Mode, filter, AGC, RIT and RF gain — the radio's API carries it — set as on every other radio.

  • Its memories on the dial. V/M, last on the swipe down: the radio's memories by name, one a detent, each with its repeater shift and tone.

  • Antennas on a hold. Hold PTT half a second for RX ANT and TX ANT, by the radio's own names — or find them on the swipe down.

  • Tune and ATU on a swipe. Swipe from the right for TUNE, a carrier at the tune power; ATU, one cycle of the radio's tuner; and its memories.

  • A web SDR beside it. Swipe down to add a KiwiSDR, Web-888 or UberSDR in your right ear.

  • PTT that tells you why. When the radio won't transmit here — out of band, or another station on the air — the knob says so.

Order · €99

Enable MultiFlex on the radio. The knob's configuration page lists the radios it hears on your network, each with Add — or give an address, or log in to SmartLink.

Read the FlexRadio guide →

VFO-Knob with the IC-705 firmware, in Icom's black and blue, showing 145.500.00 MHz FM on 2 m

Made for Icom

With an IC-705 or IC-7610, an IC-9700, an IC-7300MK2 or an IC-R8600 — and, in beta, an IC-7760 or IC-905 — the knob talks to the radio itself, over WiFi, in Icom's own network protocol — the one RS-BA1 and wfview use — with receive and transmit audio. No computer in between, and its face wears Icom's colours.

  • MAIN/SUB and antennas. On the IC-7610, swipe down to switch between the MAIN and SUB receivers and choose the antenna — or hold PTT half a second for the antenna.

  • Memories. On the IC-705 and IC-9700, V/M — last on the swipe down — puts the knob in memory mode: it steps through your programmed channels, with name, frequency, shift and tone.

  • The IC-9700's three bands. 2 m, 70 cm and 23 cm, POWER and the meter in each band's own watts, each band's memories — and the knob switches the radio's modulation input to the network for your overs, and back.

  • The IC-R8600, 10 kHz to 3 GHz. A receiver, so nothing keys it: the slab says RECEIVER. WFM among its modes, ANT1–3 on the swipe down or a press held on RECEIVER, its squelch on a swipe from the right — in every mode.

  • RF gain, power and the tuner. Swipe from the left for RF GAIN, tap it for POWER in watts — both apply as you turn. On the IC-7610, swipe from the right to put its tuner in or out of line.

  • A web SDR beside it. A KiwiSDR, Web-888 or UberSDR in your right ear, the radio in your left — see below.

  • Audio both ways. Receive audio to the 3.5 mm jack, transmit audio from the built-in microphone — the knob and the radio are a complete station. Or, set on the knob's page, transmit with the radio's own microphone: its MIC, USB or ACC, the knob only keying, as a foot switch would.

Order · €99

Read the Icom guide →

The Icom line-up

Every one of them works with the knob. The two marked Beta are built from wfview's descriptions of the radios and not yet tried on one: set the radio's modulation input to LAN yourself, and memory mode waits for a first session — whose log is very welcome.

  • Icom IC-705
    IC-705WiFi
  • Icom IC-7610
    IC-7610WiFi
  • Icom IC-7760
    IC-7760BetaWiFi
  • Icom IC-9700
    IC-9700WiFi
  • Icom IC-R8600
    IC-R8600Receiver onlyWiFi
  • Icom IC-905
    IC-905BetaWiFi
  • Icom IC-7300MK2
    IC-7300MK2WiFi

Radio photos: Icom Europe and Icom Inc.

New

Made for the X6100 and X6200

With the OpenX6X00 firmware the knob is a dial for a Xiegu X6100 or X6200 running OpenX6X00, RF.Guru's open firmware for both radios — over WiFi, with no computer in between, in OpenX6X00's own colours.

  • Over the radio's own TCI. The knob talks to the radio over WiFi, through OpenX6X00's TCI server on port 50001 — no computer in between. Tune on the radio and the knob follows; turn the knob and the radio moves.

  • It finds the radio. As x6100.local or x6200.local, the names OpenX6X00 announces on your network — when one does not answer, the knob asks for the other — or by a name or address you give it. Up to four radios, a swipe up apart.

  • Audio both ways. The radio's audio on the knob's jack, or a Bluetooth headset or speaker; the knob's microphone, or the headset's, back to the radio.

  • The radio's modes. USB, LSB, CW, CW-R, AM, NFM, DIGU and DIGL on the mode dial — on an X6200 SAM and WFM too, and after 6 m its FM broadcast from 100 MHz and airband from 118 MHz, receive only, as on the radio.

Order · €99Read the OpenX6X00 guide →

The radio's side

The radio runs OpenX6X00, with its TCI server on — as it is from the start. Get it for your radio at openx6x00.org:

OpenX6X00 for the X6100OpenX6X00 for the X6200

On the knob, choose OpenX6X00 from the setup firmware's list, on the radio's network.

Beta

Made for Zeus SDR

With the JupiterSDR firmware, a beta, the knob is a client for Zeus SDR over its TCI server on WiFi, as WSJT-X and other TCI programs are, in Zeus SDR's own colours.

  • Over Zeus SDR's TCI. Tune in Zeus SDR and the knob follows; turn the knob and Zeus SDR moves. Mode, filter, AGC and RIT on the knob's editors, the S-meter from Zeus SDR's main receiver.

  • Audio both ways. Zeus SDR's audio on the knob's jack, or a Bluetooth headset or speaker; the knob's microphone, or the headset's, back to it. On the air: SWR, forward power and the mic level.

  • Zeus SDR decides. It keys as for its own MOX button, and refuses outside the bands it allows — the knob buzzes the refusal. If the link drops on the air, the knob sends the unkey again once it is back; keep Zeus SDR's transmit timeout on.

  • With a FlexRadio. Choose the FlexRadio firmware beside Zeus SDR instead: through Zeus Link for Flex, its TCI neither keys the radio nor sends the S-meter.

Read the JupiterSDR guide →

Zeus SDR's side

In Zeus SDR, turn the TCI server on and let it listen on the network (address 0.0.0.0), port 40001. Let the computer's firewall pass that port from your network — on Linux with ufw, with your own range:

$ sudo ufw allow from 192.168.1.0/24 to any port 40001 proto tcp

Zeus SDR announces nothing on the network: on the knob's page, under Zeus SDR, give the computer's address and port 40001 — up to four computers, a swipe up apart.

On the knob, choose JupiterSDR from the setup firmware's list, stamped BETA.

Help wanted. This beta has received through Zeus SDR on one station, and has not yet been on the air through it. Run Zeus SDR? Please try it and tell us what works and what doesn't — in GitHub issue #17, or with Report a problem on the knob's configuration page. JupiterSDR is compatible with ZeusSDR; it is not made by Zeus SDR's authors.

VFO-Knob with the UberSDR firmware, in UberSDR's dark theme: S9+10 on 20 m, 14.215.00 USB, SNR 26 dB and the NR4 noise filter, the spot LU7YZ on the slab

Made for UberSDR

With the ubersdr firmware there's no radio and no computer: the knob is a dial for an UberSDR web receiver, talking to it the way its own web page does, in UberSDR's own dark theme. It only receives, so where PTT would be, the band's spots and voices are.

  • Tune a receiver anywhere. Through UberSDR's tunnel, or straight on your own network — there with no password and no time limit. Opus audio on the jack; tap a digit for the step, turn to tune.

  • Spots and voices. Where PTT is on a radio: the DX cluster's spots and every voice the receiver hears on the band, nearest first. Tap one and the receiver goes there, in its mode.

  • SNR and noise filters. The signal's height above the noise beside the S-meter, and the receiver's noise filter — OFF, NR2, RN2 or NR4 — chosen as the ring turns.

  • SSTV on a swipe. Swipe from the right for the receiver's SSTV gallery, newest first: one picture a step of the ring.

  • A KiwiSDR beside it. Swipe down for a KiwiSDR or Web-888 that follows it: the UberSDR left, the Kiwi right, BALANCE from the left.

  • The receiver's rules. As a guest through the tunnel, the session's time left at the slab's end — the knob asks before listening again — or with the owner's password. Up to four receivers, a swipe up apart; one out of reach, and the knob goes on to the next.

Order · €99

Read the UberSDR guide →

The spots and voices on the band, on the dial: SPOT 3 / 8, LU7YZSwipe from the right: the receiver's SSTV pictures, 15 PICTURESAn SSTV picture on the knob: a test pattern reading CQ SSTV
VFO-Knob with the Kiwi888 firmware: S9+10 on 20 m, 14.200.00 USB, the receiver EchoTracer, a Web-888 at Lombardsijde, on the slab

Made for KiwiSDR and Web-888

With the Kiwi888 firmware the knob is the dial of a KiwiSDR or a Web-888 — no radio, no computer. Thousands of them listen around the world; the knob tunes them as their own apps do and plays them on the jack. It only receives, so the bottom of the face names the receiver you're hearing.

  • No radio needed. The knob talks to a KiwiSDR or a Web-888 as their own apps do, and plays it on the jack — in the receivers' own look: black, yellow, a lime S-meter.

  • Four antennas a swipe apart. Up to four receivers, switched live with a swipe up — no restart, the dial stays where it was. RF.Guru's four Web-888s at Lombardsijde are one button away.

  • Antenna A/B in your ears. A second receiver in the right ear on the same frequency, mode and filter, its S-meter a thin blue line — and BALANCE from one ear to the other.

  • https receivers too. Receivers behind the kiwisdr.com proxy or Cloudflare: paste the link whole and the knob speaks TLS to it, its certificate checked as a browser does.

  • AGC, noise filter, squelch. The receiver's own, on the ring, with its modes and filters — a KiwiSDR to 30 MHz, a Web-888 to about 62 MHz.

  • The owners' limits kept. Their time limits, day limits and passwords are respected — a receiver that says no is left alone, not hammered.

Tried with RF.Guru's four Web-888s at Lombardsijde and ON3RVH's KiwiSDR in De Haan, over https.

Order · €99

Read the Kiwi888 guide →

Swipe up: RECEIVER OctaLoop, another antenna with no restartSwipe down: RIGHT EAR TerraBooster, a second receiver beside the firstSwipe from the left: BALANCE L | R between the two ears
NewReceive only

Made for OpenWebRX

With the OpenWebRX firmware the knob is a dial for OpenWebRX and OpenWebRX+ web receivers — no radio, no computer. Give it a receiver's address, like http://sdr.on4pra.be/ or https://fms.komkon.org/OWRX/, and tune.

  • Its own web protocol. The knob talks to the receiver as its web page does and plays it on the jack — OpenWebRX and OpenWebRX+ alike.

  • Up to four receivers. Each by its address on the configuration page, with Test beside it. When the one in use can't be reached, the knob goes on to the next.

  • The receiver's own bands. The dial stays within the band and stops at its edge; BAND chooses another of the receiver's bands from a list.

  • The meter in dB. As OpenWebRX's own page reads it.

Order · €99More on GitHub
NewReceive only

Made for WebSDR

With the WebSDR firmware the knob is a dial for PA3FWM's WebSDR receivers, those listed on websdr.org — no radio, no computer. It takes the receiver's stream as its page does and plays it on the jack.

  • Twente and the many others. The University of Twente's wide-band WebSDR, Maasbree and the rest listed on websdr.org — up to four, each by its address.

  • Across its bands. The dial moves across the receiver's bands by itself.

  • S-meter in dBm. With S-units beside it: S9 is −73 dBm.

  • Listed by your name. The name the receiver lists you by among its listeners is set with the receivers — and the receiver's own idle time-out is kept.

Order · €99More on GitHub
VFO-Knob with the Telephone firmware: a call to Mum, 02:47, both voices as spectra, HANG UP in red

Made for the telephone

Available now

With the Telephone firmware there's no radio at all: the knob is a telephone on your SIP account. Turn the ring to a favourite and tap CALL — the knob's microphone with the jack, a Bluetooth speaker or your Bluetooth headset are the handset.

  • Favourites on the ring. Turn to a name, tap CALL. Up to 40 favourites — typed in on the knob's page, or your starred Google contacts, kept in sync every six hours.

  • A keypad on a swipe. Swipe down to dial any number by hand — a long press on 0 gives +. In a call, the same keys go out as DTMF, for menus and voicemail.

  • It rings like a phone. A call coming in buzzes in the ring's own rhythm, the ANSWER slab breathes green and the rim lights up — and it rings in a headset or speaker too. Answer or decline with a tap, or with the headset's button.

  • Your SIP account, no fuss. The provider's user, password and server — it registers over UDP and finds its own way out through your router: no STUN, no port forwarding. G.711 audio.

  • Both voices on the face. In a call, two spectra: the other end's on the left, yours on the right — with the call's time, who it is with, and mute a tap away.

  • Hands free. The knob's own microphone with the jack, a Bluetooth speaker for the room, or a Bluetooth headset that opens for calls only, as with a mobile phone.

Order · €99

Read the Telephone guide →Google Contacts setup →

Turn: the next favourite, and CALL on the slabA call coming in: the knob rings and buzzes, ANSWER in greenSwipe down: the keypad, to dial a number by hand
Beta

Made for a phased array

With the epibeam firmware, a beta, the knob is the beam switch for a phased array — a 4-square, or an array of 8 directions — on its way to EpiCenter, the station's master, which switches the array. Turn it a direction a detent; once it rests, it counts the direction out in clicks, for a hand that isn't looking.

  • The array. A 4-square, steered N, E, S or W, or 8 directions with the corners between — chosen on the configuration page, the beam kept on its heading.

  • The dial. A direction a detent, round and round. Once it rests, the knob counts the direction out in strong clicks: N one, on round clockwise — W four on a 4-square, NW eight on 8.

  • The ring. The directions round the glass's edge, the beam's lit in gold: a tap on one goes straight to it.

  • Kept. The direction, across a restart. No PTT, no swipes, no audio: the whole glass is the beam's.

Read the EpiBeam guide →

A 4-square on E, 90°: a direction a detent, and at rest E counted out in two clicks8 directions on SW, 225°: the corners between N, E, S and W

A beta. This first release is the knob's side: it keeps the beam you choose and counts it out, but has no link to EpiCenter yet, so no relay moves — its face says EpiCenter: not connected. The setup firmware's list stamps it BETA.

The radar at 75 NM: aircraft coloured by altitude, an emergency called out in red, a range a detentA tap on an aircraft: UAE183, a B77W from Dubai to Brussels, its level, speed and where it is
New

The aircraft round you

With the adsb firmware the knob is a radar of the aircraft round you — no radio needed. They come from adsb.fi, adsb.lol or airplanes.live, which gather what receivers all over the world hear, or from your own readsb, dump1090 or tar1090.

  • Where you are. North up, the middle an airport by its ICAO code or your station's latitude and longitude — Brussels Airport, EBBR, until you set it.

  • The dial is the range. 5 to 250 nautical miles, or 10 to 450 km, a detent each; the rings, the coasts and borders and the airports follow.

  • Each aircraft. An arrow along its track, coloured by its altitude, the nearest labelled with callsign and level. A tap: its card — type, registration, speed, squawk and its route, from adsbdb.

  • Called out. An emergency squawk in red, with a buzz; a type on your own list — A400, C17, B74* — in gold, with a click.

Read the ADS-B Radar guide →

The feeds. adsb.fi and adsb.lol answer anyone; airplanes.live answers only once its people have been written to — the guide says how. After Alex-developer's ADSB-Radar (MIT); the map from Natural Earth and OurAirports, both public domain.

New

A clock for the shack

With the clock firmware the knob is a clock for the radio room — no radio needed: local time on the hands, UTC on a 24-hour ring with its own red hand, the date, and ten alarms.

  • Four faces. The shack clock, with UTC on its 24-hour ring; the Diver, its bezel and sweeping second hand; Classic white, a station clock; and Digital. A face a detent, the one it rests on kept.

  • Ten alarms. Each a time, its days and on or off — set on the knob with the dial, or on its page. The next to ring is on the face, with a bell.

  • Rings as you like. The motor, the sound or both. The beeps grow louder over 30 seconds, in a Bluetooth headset or speaker when one is connected, else on the jack.

  • A tap stops it. A turn snoozes it, 9 minutes until set; left alone, it stops after 10. Even with the knob locked.

Read the Clock guide →

The shack clock: local time on the hands, UTC on the 24-hour ring, the next alarm at 07:30 with a bellAn alarm ringing: 07:30 in a flashing red ring — tap to stop, turn to snooze

The time. From pool.ntp.org over WiFi; a day without an answer, and the hands turn grey. A screen to look at, so no screensaver and never dark until you set one. The faces follow ideas from MilovdZee's Analog_Clock-esp32 and Alan Wang's Saiko watch; none of their code is in the firmware.

The next 24 hours: the chance of rain as blue bars, the temperature as an orange lineThe next 5 days: each day's sky, highest and lowest, and its chance of rain
New

The weather where you are

With the weather firmware the knob is a weather station for one place — no radio, no key, no account: the weather now, the next 24 hours and the next 5 days, from Open-Meteo's forecast. The pages roll on by themselves, and the dial turns them.

  • Your place. A town found by its name, a latitude and longitude, or your Maidenhead locator. °C or °F; the wind in km/h, m/s, knots, mph or Beaufort.

  • Now. The sky, the temperature and what it feels like, the wind with its gusts, humidity, pressure, sunrise and sunset.

  • The next 24 hours, the next 5 days. The chance of rain as bars and the temperature as a line, and when rain is likely; each day's sky, highest and lowest.

  • Pages that roll on. Every 5 seconds until set, or a detent each on the dial. When Open-Meteo doesn't answer, the last forecast stays, with why.

Read the Weather guide →

Weather data by Open-Meteo.com, under CC BY 4.0. Open-Meteo is free, without a key, for use that is not commercial; the knob asks it for one place, every 10 minutes at the most. Place names from Open-Meteo's geocoding, from GeoNames. The idea of a weather face is after Yumo's Smart Cube; none of its code is in the firmware.

Up and running in minutes

Pick your radio on the knob, and for AetherSDR two more steps — the last one is optional. Other radios are set up on the knob's own page. Every step, with the knob's own screens, is in the guides. A knob that will not start, or that you want to start over? Update it over its cable, from Chrome or Edge.

  1. 1

    Pick your radio

    Join the knob's WiFi, VFOKnob, with your phone and choose your network. The first time, the knob puts every firmware on its SD card — a few minutes, once. Then turn the ring to your radio's firmware and tap to install it — one still in beta is stamped BETA. For AetherSDR, the rest is below.

  2. 2

    Autostart TCI in AetherSDR

    Install AetherSDR if you haven't yet — it's free for Windows, macOS and Linux. Then open its Settings menu and switch on Autostart TCI, so the knob finds it every time.

  3. 3

    Plug it in

    Connect the knob to the computer running AetherSDR with a USB-C cable and give it about ten seconds — nothing to install on Windows, macOS or Linux. If the knob says FLIP USB-C, flip the connector upside down. It picks the cable as it starts: one already running on its battery stays on WiFi until you Reboot it from its page.

  4. 4

    Configure (optional)

    Browse to http://10.55.42.1, sign in with admin / admin and set your own password first — the knob can key a transmitter. Then audio levels, and for cordless use the AetherSDR computer's address.

Over the cable there's nothing to set up — bar a strict Linux firewall. From firmware 1.24.2 the computer can also pass the knob's traffic on to the internet, for its clock and its own update checks — optional, and in the AetherSDR guide. On WiFi the knob connects to AetherSDR across your network, so the computer's firewall has to let it in:

Windows

USB-C Plug in and tune: Windows brings the knob up by itself — nothing to install, nothing to allow.

USB-C Optional: the internet on the cable. Tried on Windows 11, any edition: Internet Connection Sharing, once it is pointed at the knob's addresses — out of the box it gives the cable addresses of its own. First, from an administrator PowerShell:

PS> $p = 'HKLM:\SYSTEM\CurrentControlSet\Services\SharedAccess\Parameters'PS> Set-ItemProperty $p ScopeAddress 10.55.42.2PS> Set-ItemProperty $p ScopeAddressBackup 10.55.42.2PS> Restart-Service SharedAccess

Then Win+R, ncpa.cpl: the knob is the connection with UsbNcm Host Device under its name. Right-click the one with the internet, Properties → Sharing, tick Allow other network users to connect, and choose the knob's under Home networking connection. Windows can forget the sharing when it restarts: the guide has Microsoft's fix.

WiFi If you allowed AetherSDR on private networks when Windows first asked, you're set. Otherwise make sure your home network is set to Private, then open AetherSDR's TCI port to it once, from an administrator PowerShell:

PS> New-NetFirewallRule -DisplayName "VFO-Knob TCI (WiFi)" `  -Direction Inbound -Protocol TCP -LocalPort 50001 `  -RemoteAddress LocalSubnet -Action Allow -Profile Private

macOS

USB-C Works out of the box — plug in and tune.

USB-C Not tried yet Optional: the internet on the cable. en0 stands for the Mac's own way to the internet; route get default names it:

$ sudo sysctl -w net.inet.ip.forwarding=1$ echo "nat on en0 from 10.55.42.0/24 to any -> (en0)" | sudo pfctl -a com.apple/vfoknob -f -$ sudo pfctl -E

WiFi Works by default too. If you've switched the macOS firewall on, allow incoming connections for AetherSDR: System Settings → Network → Firewall → Options.

Linux

USB-C Binds the knob by itself — nothing to install. If your firewall drops incoming connections (ufw, or firewalld's public zone), let the knob's cable address in once:

$ sudo ufw allow proto tcp from 10.55.42.1 to any port 50001

USB-C Optional: the internet on the cable. The first two last until the computer restarts. The third is only for ufw, which drops forwarded traffic by default, and it stays:

$ sudo sysctl -w net.ipv4.ip_forward=1$ sudo iptables -t nat -A POSTROUTING -s 10.55.42.0/24 ! -d 10.55.42.0/24 -j MASQUERADE$ sudo ufw route allow from 10.55.42.0/24

WiFi Let your local network reach AetherSDR's TCI port too. Use your own range — a /24 like 192.168.1.0/24 or a /16 like 10.0.0.0/16:

$ sudo ufw allow proto tcp from 192.168.1.0/24 to any port 50001

50001 is AetherSDR's default TCI port. More help on GitHub: if the page doesn't open · if the knob says NO LINK.

The VFO-Knob on YouTube

Others set it up, try it and say what they think: our playlist, as it grows. Play it all or pick a video; a video loads from YouTube only when you press play.

RfGuru Touch VFO Knob & ICOM 705 SET UPHamTech - M0FXB Ham Radio Scanner - DroneTech · 30 October 2026 · on YouTube

4 videos in the playlist

The playlist on YouTube

Built to be trusted with a transmitter

Signed, fail-safe updates

Latest firmware: v1.25.2

Firmware images are RSA-3072 signed and verified before they're accepted. On WiFi the knob checks at start-up and once a day, and asks on the screen — UPDATE x.y.z, tap here to install. One tap installs it; anything else and the question goes away. It never asks while you transmit and never installs unasked. 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 that looks after itself

PTT is a toggle, so the radio stays keyed when you let go. That's why the screen changes colour on the air behind a red PTT bar you can't miss. If something goes wrong, the knob steps down in stages — unkey, close the connection, then drop it — and AetherSDR unkeys as soon as it sees the connection close. A key the radio never confirms ends by itself after a second and a half. Set your radio's own transmit time-out too (in AetherSDR: Radio Setup → TX → Timeout): the radio enforces it itself, whatever happens to the knob or the link.

Safety notes

Specifications

Works with
AetherSDR on Windows, macOS and Linux · FlexRadio 6000/8000 (MultiFlex) · Icom IC-705, IC-7610, IC-9700, IC-7300MK2, IC-R8600 — and IC-7760, IC-905 in beta · Xiegu X6100 and X6200 on OpenX6X00 · Zeus SDR (JupiterSDR, in beta) · UberSDR, KiwiSDR, Web-888, OpenWebRX and WebSDR web receivers · SvxLink reflectors · SIP telephone · a radar of the aircraft round you (ADS-B Radar) · a clock for the shack, with ten alarms (Clock) · the weather where you are (Weather) · a phased array's beam switch (EpiBeam, in beta) — more radios in the pipeline
Protocol
AetherSDR: TCI v2.0 over WebSocket · FlexRadio: the radio's own API, Opus audio · Icom: Icom's network protocol · OpenX6X00: the radio's own TCI server · JupiterSDR: Zeus SDR's TCI server · UberSDR: its own protocol, Opus audio · KiwiSDR/Web-888: their own protocol, http or https · OpenWebRX and WebSDR: each its own web protocol, as its page uses · Telephone: SIP over UDP, G.711 · SvxLink: protocol 3.0 over TLS, Opus audio
Tuning dial
CNC-machined metal ring around the screen, rotary encoder, with acceleration
Display
1.8″ round IPS, 360 × 360, 262K colours, 600 cd/m², 1200:1 contrast · a screensaver — Matrix rain, a clock or the frequency drifting — then dimmed, then dark
Touch
Capacitive
Haptics
Vibration motor with its own driver — silent while transmitting
Processor
Dual-core ESP32-S3 at 240 MHz · 16 MB flash · 8 MB PSRAM
WiFi
2.4 GHz 802.11 b/g/n, internal antenna · remembers four networks
Storage
Built-in microSD card: every firmware, to switch radios without internet — and every firmware's settings, in three copies, so a power cut never loads them half-written
USB-C
USB network adapter (CDC-NCM) — no drivers, no setup · power and charging
Audio out
3.5 mm jack, high-performance stereo DAC
Microphone
Built-in digital microphone, or the headset's — or, if you choose, the computer's on AetherSDR and the radio's own on an Icom, the knob its PTT
Bluetooth
Headsets (hands-free, wideband speech; call button or boom arm as PTT) and speakers (A2DP, volume from the knob) — their battery on the face
Meters
S-meter · SWR · forward power, auto-ranging to 2.5 kW · mic level · 1 s peak hold
Case
CNC-machined metal, blue · Ø 66 mm · 22 mm high
Power
Built-in rechargeable battery, its charge on the face · runs and charges over USB-C
Web SDR
KiwiSDR, Web-888 or UberSDR beside the radio, http or https — Icom, FlexRadio and UberSDR firmwares; with no radio: the UberSDR, Kiwi888, OpenWebRX and WebSDR firmwares
Radios
Up to four per firmware, switched with a swipe up; FlexRadio SmartLink
Web page
vfo-knob.local — radio controls, settings, firmware; password-protected, with a password of the knob's own over WiFi
API
JSON over HTTP: read and set frequency, mode and more — for logbooks and other programs
Updates
RSA-3072 signed, offered on the dial, automatic rollback
Firmware
Open source, Apache-2.0 — picked on the knob, switchable any time

Open-source firmware

Apache-2.0

Read it, build it, change it. The source, the build instructions and the full setup guide live on GitHub.

v1.25.2ESP-IDFApache-2.0
View on GitHub

Questions, answered

Which firmware does it come with?
All of them, in a way: the knob starts with the firmware picker. Join its WiFi with your phone and choose your network — the first time, it puts every firmware on its microSD card, a few minutes, once — then turn the ring to your radio — AetherSDR, FlexRadio, Icom, OpenX6X00 for a Xiegu X6100 or X6200, SVXConnect, Telephone, a web receiver — UberSDR, Kiwi888, OpenWebRX or WebSDR — ADS-B Radar, a radar of the aircraft round you, the Clock, the Weather, or, in beta, JupiterSDR, a client for Zeus SDR, and EpiBeam, a phased array's beam switch. It installs that firmware from the card in a few seconds, its signature checked, and starts it. The list comes from the update server each time, so a new firmware shows up on every knob the day it's released, and the card keeps a copy of every one, so switching radios works even without internet. Nothing to choose when you order.
Which radios does it work with?
Today: AetherSDR — and through it FlexRadio 6000, 8000 and Aurora-series transceivers — over USB-C or WiFi; FlexRadio 6000 and 8000 directly, as a MultiFlex station; the Icom IC-705, IC-7610, IC-9700, IC-7300MK2 and IC-R8600 directly over WiFi; the Xiegu X6100 and X6200 on OpenX6X00, their open firmware, over WiFi; and — with no radio at all — UberSDR, KiwiSDR, Web-888, OpenWebRX and WebSDR web receivers, SvxLink reflectors, a SIP telephone, a radar of the aircraft round you, a clock for the shack and the weather where you are, over WiFi. The Icom IC-7760 and IC-905 are in beta, as are JupiterSDR, the knob as a client for Zeus SDR, and EpiBeam, the knob as the beam switch for a phased array; older radios will follow through a Raspberry Pi bridge on their USB port; tell us which one you'd like next.
Can I switch the knob to another radio later?
Yes, any time and without a computer. Hold a finger on the S-meter until the knob clicks, then hold it again until it buzzes, and turn the ring for yes: the knob goes back to the firmware picker, keeping your WiFi. Or choose another radio under Firmware on its configuration page. Each firmware's settings stay on the knob's SD card, so going back to one later finds its radios, logins and choices as they were.
What if the knob will not start, or I want to start over?
Yes, from Chrome or Edge on a computer, over its USB-C cable: update it over its cable. The newest setup firmware goes on with its WiFi, Bluetooth pairings and settings kept — or, if you choose, the whole knob is erased and set up as it shipped, every firmware back on its SD card, and it asks for WiFi as a new one does.
Does it work with SmartSDR?
Yes, with the multiflex firmware: the knob talks to the FlexRadio itself as a MultiFlex station, and can be the dial and PTT for a SmartSDR station already on the radio — or a remote transceiver of its own beside it. The AetherSDR firmware talks to AetherSDR, which is free and open source for Windows, macOS and Linux and also runs alongside SmartSDR and Maestro through MultiFlex.
Do I need to install anything?
With the AetherSDR firmware, only AetherSDR, if you don't have it yet; with the others, nothing at all. The firmware is already on the knob, Windows, macOS and Linux all bring it up over USB-C by themselves, and everything else happens in your browser. Going cordless? Your computer's firewall may need to let the knob in once — see the notes under Setup.
The knob says FLIP USB-C — what now?
Flip the USB-C connector upside down and plug it back in. The knob's USB-C socket only works one way round: the other way, the cable reaches a second chip on the board instead of the knob itself, so the knob finds no computer and shows FLIP USB-C. Nothing is wrong — it just needs the other side up. If WiFi is already set up, the message only shows for a few seconds before the knob carries on over WiFi, so watch it start.
Can I use a Bluetooth headset or speaker?
Yes. Pair it once on the knob's configuration page and the knob calls it whenever it switches on. Have a headset and a speaker? The page lists the last eight devices connected: Connect beside one goes over to it, no pairing mode. With a headset you hear the radio in it, talk through its boom microphone, and key with its call button — or, on a Jabra, the boom arm. A speaker plays the knob's audio while you talk into the knob's own microphone. It's made with the Jabra Evolve2 65, Mono or Stereo, and the JLab Pop Party, Sony SRS-XB100 and Marshall Stockwell III speakers; other hands-free headsets and A2DP speakers should work too.
Does it show how much battery is left?
Yes. Unplugged, the knob shows its own charge at the top of every face — green, yellow, then red; on the Clock only once it is low — and as a percentage on its address card and configuration page; on USB power it shows none. A Bluetooth headset or speaker that reports its charge has its own battery beside its logo.
Is there a step-by-step manual?
Yes: a guide per firmware, with the knob's own screens — from the first start-up with your phone to transmitting, and back to the firmware picker.
Can I use it with more than one radio?
Yes. Each firmware keeps up to four — an IC-705, an IC-7610, an IC-9700 and an IC-R8600; two FlexRadios; AetherSDR on two computers. Swipe up, turn to one and tap: the knob restarts into it. On the FlexRadio firmware, your SmartLink account's radios join the list.
What happens to my settings in a power cut?
Nothing: every firmware keeps its settings on the knob's built-in SD card, in a folder of their own, VFO-CFG — three copies of each, written in turn and read back, so a power cut never leaves them half-written and the knob starts with them as they were saved. Your WiFi networks and Bluetooth devices stay in the knob itself. Should the card ever stop answering, the knob says NO SD CARD and carries on with its own copy; the setup guide says what to do.
Can my logging program read the frequency?
Yes. The knob answers http://vfo-knob.local/api/radio with the radio's frequency, mode and the rest as JSON, and takes settings the same way — see “Your radio in a browser”. It needs the knob's login — over WiFi, the password of its own the page asks for at the first visit — and nothing there transmits.
Can it really be a telephone?
Yes, with the Telephone firmware: give it your SIP provider's account and it registers by itself — no port forwarding. Turn to a favourite and tap CALL, or swipe down for the keypad; calls coming in ring and buzz. Your starred Google contacts can be its favourites, read-only and synced every six hours.
What if I take the knob somewhere else?
It remembers up to four WiFi networks and joins whichever is in reach. Where none of them is, it puts up its own VFOKnob hotspot after about 25 seconds: join it with your phone, pick the network there, and the knob carries on with your radio. Back home, it simply joins again.
Can it stay on the cable all day?
Yes. Started with the cable to the computer running AetherSDR, it runs from it and charges its battery, always on at your desk. It chooses as it starts: started on its battery it runs on WiFi, and stays on WiFi when you plug it in, until you Reboot it from its page.
Does it need the internet?
No. Over USB the knob and your computer share a private link with nothing behind it. On WiFi the knob checks GitHub for signed firmware updates every 24 hours while it's switched on — you can change that, or switch it off.
What if the knob loses power or its link while transmitting?
While the knob can still reach AetherSDR it unkeys within about two seconds: it sends an unkey, then closes its connection, and AetherSDR unkeys the moment that close arrives. If nothing can reach AetherSDR any more — the knob loses power, its battery runs flat, WiFi drops out — the radio stays keyed until the computer gives up on the connection, which can take many minutes. We've proposed a fix upstream (aethersdr#5985); until it ships in an AetherSDR release, don't make the knob the only PTT on an unattended station.
Is the firmware open source?
Yes — Apache-2.0, on GitHub. Read it, build it, change it. Nothing is locked: the board always stays ordinarily flashable.
Where do I report a problem, or ask for a feature?
On GitHub Issues, one problem or one idea per issue. The knob makes its own report: Report a problem, at the bottom of its configuration page, opens the form with it filled in. What else to give, and where a feature goes, is on Reporting a problem. For an order or its shipping, ask RF.Guru's support.

Questions before you order?

Which radio, your station, your operating system — ask the RF.Guru team and we'll help you get tuning.

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