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138.00 EUR (115.00 EUR + VAT)
Availability: Back Order
Not Rated
138.00 EUR (115.00 EUR + VAT)


The Microham USB interface III is a low cost, high performance USB interface that provides high quality build-in sound card for digital modes, with optically isolated transceiver CAT control, CW and PTT. These USB Interfaces provide a solution to the lack of available Serial (COM) ports on laptop and newer desktop computers for controlling your radio. 

The Microham USB interface III includes full optical isolation of all control signals (radio control, CW,  PTT and Squelch) and built-in USB sound card with front panel level controls for transmit via your transceiver's Accessory audio input and the constant level (pre-volume control) audio output. 

Microham USB Interfaces have built-in hardware support for your radio - you no longer need additional level converters like CT-62, IF-232, FIF-232, CT-17.   USB Interface III includes support for CW keying (DTR) and PTT (RTS) as well as a detector/driver for pseudo-FSK and QSK CW on the soundcard's right audio channel for use with FLDIGI on any platform. USB Interface III uses same cable as USB Interface II or DIGI KEYER.

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 Interface III box contains: device, USB A/B cable, clip on ferrit rfi filter

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. 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 USB interface III block diagram:

Microham USB interface III features:

Just one USB port for audio and Control  
Complete "Computer <-> Radio" 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
- based on FTDI chip
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

Microham USB interface III specifications:

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.)
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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