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The new micro KEYER III from microHAM is Amateur Radio first 24-bit USB Audio Transceiver Interface.

Contact us if you need a radio specific cable!

434.27 $

  • EUR: 399.00 €
  • SEK: 4 517 kr

Out of stock

micro KEYER III™ is the world first and the only amateur radio USB interface featuring high dynamic range, 24-bit audio processing chain on all signal stages. It is the most powerful single radio All-In-One USB interface and the only USB interface to fully support digital and voice operation including microphone switching in one box.

With a single USB port, micro KEYER III™ works with any Windows-based logging or control program for CW, Voice, FSK and Digital operation (RTTY, FT8, WSJT, PSK31, SSTV, etc.). micro KEYER III™ works also on Linux using DJ5QV’s mhuxd Router, and macOS apps natively supporting micro KEYER III™.

micro KEYER III™ includes a CAT, radio control interface that supports all common standards (RS-232, CI-V, Kenwood and Yaesu TTL), a powerful CW memory keyer using genuine K1EL’s WinKey, a Digital Voice Keyer for SSB, two channel audio processing for transceivers with dual receivers, automatic microphone selection, and a buffer/sequencer for amplifier or LNA control.

Compared to 16-bit audio interfaces, or to any USB enabled transceiver, including flagship transceivers from well known manufacturers (as of autumn 2018), unique 24-bit USB audio processing in the micro KEYER III™ provides advantage in higher dynamic range (>105dB) and lower noise floor, preserving transceiver performance also for audio processing on computer (digital modes), otherwise limited by 16-bit USB audio signal chain. Please see an introductory video below and check here independent measurements done by Wofgang OE1MWW.

For connection to the transceiver micro KEYER III™ uses special, transceiver specific DB37 cable, same as used with original MK, MKII or MK2R+. micro KEYER III™ keeps full backward compatibility for native control from logger programs and is compatible with all accessories made for MKII.

Along with completely new audio, micro KEYER III™ brings quite a lot of new features too. For more details or check what’s new or different compared to previous MKII model, please click Features button below or check the manual.


microKEYER III Features

 Features and functions printed in orange color are new compared to previous generation MKII
  • Single USB connection to computer
  • Stand alone operation
  • Complete “Computer ↔ Transceiver ↔ Amplifier” galvanic isolation
  • Internal 24-bit USB Audio
  • Standard USB Audio Class device – no custom driver required
  • Superior asynchronous USB audio data transfer
  • Internal low phase noise LO: -145dBc/Hz @1kHz
  • High dynamic range: 110 dB typical, 105 dB minimum
  • Separate and simultaneously operating Line and Microphone USB Audio Inputs
  • Extremely low noise floor: as low as <10µV effective
  • Additional Optical S/PDIF audio input/output ports
  • iLINK port for digital connection to iLINK enabled devices (Station Master, Station Master DeLuxe, SMΩRF) for frequency and data exchange
  • Real-Time audio levels monitoring on built-in color OLED display
  • Silent switching of all audio signals without relays
  • DSP for all analog signals, including microphone inputs


Radio control (CAT):

  • Two, managed (CAT protocol controlled) CAT ports for connecting two loggers at the same time
  • Up to 57600 Baud with handshake support
  • Integrated level converter for CI-V, FIF-232, IF-232, or RS-232 levels
  • Supports most Elecraft, Icom, Kenwood, Ten-Tec, Yaesu and other radios
  • Simplex SDR receiver tracking feature (Kenwood and Icom protocol supported)


Voice (SSB/AM/FM):

  • Two microphone support for headset and hand/desktop mic
  • Fixed or automatic microphone selection
  • Menu driven settings, no jumpers and trimmers
  • Individually adjustable Gain, Bias, Tone Emphasis and ALC supports seamless use of electret and dynamic microphones combinations
  • Individual “Voice” monitor loop-back for “TX Audio recording”
  • Digital Voice Keyer with nine messages per bank, up to 120 seconds each, unlimited number of banks


Digital (FSK/AFSK):

  • 24-bit, high dynamic range, very low distortion analog inputs
  • Dual channel receive capability
  • Ultra low noise floor for optimal decode level
  • Front panel transmit and receive level control knob
  • Separate Data PTT output for digital audio modes operation (AFSK) with microphone muting
  • True analog feel, low latency RTTY tuning indicator (crossed ellipses)
  • UART based, zero jitter FSK output
  • Re-sampled standard 45.0 Baud rate for accurate 45.45 Baud HAM RTTY speed
  • Intelligent diddle stuffing for no random gaps between characters
  • Supports data codes with 5/6/7/8 data bits and 1/1.5/2 stop bits
  • Sample accurate support for audio based P-FSK keying
  • Unique, hot switch protected FSK keying
  • Adjustable FSK keying polarity
  • PS/2 keyboard or keypad support for stand alone FSK transmission with type ahead function
  • Nine (9) user programmable FSK memories



  • Genuine WinKey™ v3 chip
  • Front panel speed knob
  • Selectable side tone for external speaker with “paddle side tone only” function
  • Individual side tone for “TX Audio recording”
  • Sample accurate support for audio based Q-CW keying
  • PS/2 keyboard or keypad support for stand alone CW “memory keyer” with type ahead function
  • Nine (9) user programmable memories
  • Logger independent contest auto-numbering (Field Day style)


  • 1 Watt amplifier for monitor/sidetone
  • Main OLED display
  • Isolated, high voltage optoMOS based PA and LNA keying outputs, no relays
  • CI-V output for controlling CI-V compatible Power Amplifiers or other accessories
  • Serial output for controlling stepper motor based antennas
  • User presets to recall all parameters for different logger or control programs
  • Huge filtering for maximum RFI immunity
  • Metal/Aluminum case, powder coated and silk screened
  • Free, no time limit firmware/software upgrades via Internet
SKU: MKIII Category: Tag:

micro KEYER III Specifications


  • USB 2.0 Full speed, isolated
  • FTDI USB – serial
  • UAC1 asynchronous downstream, max. 24-bit/48kHz, asynchronous/synchronous upstream, max. 24-bit/96kHz

Power consumption:

  • USB – less than 10mA
  • Power supply – max. 450mA @ 13.8VDC (max.16VDC)

Radio Port:

  • RxD, TxD – max. 57600 Baud, RTS/CTS handshake supported
  • Levels: FIF-232, IF-232, CI-V, RS-232
  • Aux Port: TTL – RxD, TxD, no handshake – max. 19200 Baud
  • CI-V Port: open collector bus – max. 19200 Baud


  • open collector, max 30V/400mA


  • optoMOS, max. 300VAC/VDC @ 0.1A

Foot Switch, PTTIN:

  • active when closed to ground, max load: 1 mA at 5V


  • Mono, 1 Watt @ 4 Ohm speaker

Audio Line Output:

  • 600 Ohm, max. 1.5Vp-p
  • AC coupled

Audio Mic Output:

  • 600 Ohm, max. 370mVp-p
  • AC coupled

Audio Line Input:

  • 10K Ohm, max 5Vp-p
  • dual channel (Stereo)

Dynamic Range:

  • min. 105dBA, typ. 110dBA
  • THD: 0.0009%
  • IMD+Noise: 0.004%
  • AC coupled


  • W 232mm (9.125″) x H 44mm (1.73″) x D 105mm (4.125″)


  • 1.3 kg (1.875 lbs.)

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