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394.81 EUR (329.01 EUR + VAT)
Availability: Back Order
Average Rating: Not Rated
Manufacturer: Microham
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Microham 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, Microham 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 Microham micro KEYER III.

Microham 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 Microham 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. 

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

The interface is suitable for connecting any type of transceiver that has a CAT port. For example, Yaesu, Kenwood, Icom, Elecraft, Ten-Tec.

MicroHAM USB Micro KEYER III box contains: device, power connector (the power cord must be made by you), USB A / B cable, clip on ferrit rfi filter, microphone adapter, RCA / RCA cable, 3.5mm jack audio cable

The device is compatible with a wide range of radios, so you need to create a radio-specific cable, it is not supplied in the box. If necessary, we can manufacture these cables and you can ask for our unique quotation! Cabling and device setup can be downloaded here: http://www.microham.com/contents/en-us/d137.html

Driver software and user manual can be downloaded here: http://www.microham.com/contents/en-us/d29_downloads.html

Microham Micro KEYER III features:


  • 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 or control programs 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
  • Optimized for future “Remote Control Suite” connection
  • Huge filtering for maximum RFI immunity
  • Metal/Aluminum case, powder coated and silk screened
  • Free, no time limit firmware/software upgrades via Internet

Microham Micro KEYER III specifications:


USB 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
CW open collector, max 30V/400mA
FSK open collector, max 30V/400mA 5/6/7 bit data, 1/1.5/2 stop bits, up to 300 Baud
PTT1 open collector, max 30V/400mA
PTT2 open collector, max 30V/400mA
PA PTT optoMOS, max. 300VAC/VDC @ 0.1A
LNA PTT optoMOS, max. 300VAC/VDC @ 0.1A
Foot Switch active when closed to ground, max load:1 mA at 5V
PTT IN active when closed to ground, max load:1 mA at 5V
Monitor 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 In 10K Ohm, max 5Vp-p dual channel (Stereo)
Dynamic Range min. 105dBA, typ. 110dBA
THD 0.0009%
IMD+Noise 0.004% AC coupled
Dimensions W 232mm (9.125") x H 44mm (1.73") x D 105mm (4.125")
Weight 1.3 kg (1.875 lbs.)



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