USB Interface III

USB Interface III

Price: $245.00

Manufacturer: microHAM
Availability: IN STOCK

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Interface III Features

Interface III block diagram


  • Just one USB port for audio and Control
  • Complete “ComputerRadio” electrical isolation
      – bidirectional transformer isolation between sound card and radio
      – ALL digital signals: Radio Control, CW, PTT, FSK, and Squelch, optically isolated from USB port
  • Standard Sound Device – no custom drivers
      The USB Sound Device is an industry standard device recognized by
      Windows XP and Vista (all versions), Macintosh OS 10 and LINUX. There are no custom device drivers to install and no compatibility problems with your applications. Windows 98SE is not supported.
  • Ultra low noise:
      – The sound circuits are designed with special attention to low noise
      – Receive noise floor is better than -90 dBm (typical) in 600 Ohms.
      – 87 dB (typical) dynamic range rivals that of professional products.
      – Special circuit design maintains full dynamic range and low noise floor with all radios – both high level and low level outputs.
  • Independent transmit and receive clock
      – Transmit clock: 32000, 44100, 48000 Hz
      – Receive clock: 8000, 11025, 16000, 22050, 32000, 44100, 48000 Hz
      – sampling rates are native: no up/down conversion or “rounding” errors
  • Right channel audio detector and FSK/CW driver
      – FSK output for FDIGI “pseudo-FSK” mode
      – Provides a “hard keyed” CW output for software that generates only audio (sidetone) CW
  • Support for all radio control standards (CI-V, FIF-232, IF-232, RS-232)
      – fully supports Icom, Kenwood, Ten Tec, Yaesu and other radios
      – no separate level converter required
  • Squelch input for signaling to computer
      – two inputs, one is active low, second is active high
      – ideal for Echolink and remote interfacing applications
  • No external power adapter for most transceivers
      – Computer part is powered from USB
      – Radio interface is powered from transceiver or transceiver power supply
  • Strong immunity to RFI
      – integrated chokes and filters for best RFI immunity
      – advanced shielding and circuit design for RFI product suppression
  • Quick change connectors
      – USB
      – Radio – DB15
  • LEDs for easy visual feedback of CAT, CW, PTT, SQL
  • Metal/Aluminum case, powder coated and silk screened
  • Free software upgrades via the internet


  • Power Consumption: USB < 200mA, Transceiver, < 100mA @ 13.8V.
  • Radio Port: RxD, TxD, max. 57600 Baud
  • Levels: jumper selectable TTL, inverted TTL, open collector bus or RS-232
  • CW: open collector, driven from DTR or audio detector, max 30V/400mA
  • PTT: open collector, driven from RTS, max 30V/400mA
  • FSK: open collector, driven from DTR (MMTTY with EXTFSK) or audio detector (FLDIGI/pseudo-FSK)
  • SQL: input, closed to ground or high (two inputs) to activate. Wired to CTS
  • Audio Out (left):
  • Output Level: 1.3V p-p max.
  • Response: 100 Hz – 10 KHz +1dB/-3dB
  • Second Harmonic: -80 dB (typical)
  • Third Harmonic: -70 dB (typical)
  • D/A Sample rates: 32000, 44100, 48000 Hz
  • Audio Out (right):
    Internal Pseudo-FSK/QSK CW detector.
    drives CW and FSK outputs
  • Audio In (left):
  • Input Level: 4V p-p max.
  • Response: 300 Hz – 3 KHz +/- .5 dB (typical)
  • Absolute Noise Floor: -90 dB @ 600 Ohms
  • Dynamic Range: 87 dB (typical)
  • D/A Sample rates: 8000, 11025, 16000, 22050, 32000, 44100, 48000 Hz
  • Dimensions: W 103mm (4 1/8″) x H 28mm (1 1/8″) x D 101mm (4″)
  • Weight: 1100 g (2.4 lbs.)
  • Under Microsoft Windows, the microHAM USB Device Router can create/map the USB III to separate virtual serial ports for control, CW, and PTT. With OS X and LINUX the control, software CW and PTT outputs are provided on a single TTY device using native drivers for that operating system. The USB soundcard uses native drivers for each operating system.


Minimum – 800 MHz IBM PC compatible computer with Windows 2000, 64 MB RAM, CD-ROM, USB1.1 port, Transceiver, logger or control software (any)

Recommended – 1.6 GHz PC with Windows XP or higher, 256MB RAM, CD-ROM, USB2.0 port, Transceiver with computer port, logger or control software (any)
Also Supported – Apple G4 or later with OS X 10.4 or later and current LINUX distributions.

Note: Windows 98 (any version) is not supported.

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