microHAM USB-III: CAT- and Sound Interface with soundcard

USB-III Interface

The USB-III CAT interface contains an own soundcard, which is connected via USB to the computer. So you don't need separate audio cables to the computer anymore, the original sound card of your computer remains free for other applications. The sound card of the USB-III device offers two distinct advantages over standard cards: a lower noise level and a higher dynamic range (typ. 87dB). This makes this sound card much more suitable for demanding amateur radio applications. All connections to and from the computer and radio are isolated either by transformers or optically. Control lines exist for CAT, PTT, CW/FSK and Squelch.

The USB-III interface works with all computers with USB connector. Drivers are available for Windows 2000/XP/Vista/Win7 32/64-Bit, as well as Apple G4 with OS-X 10.4 or later, and for up to date Linux distributions. Windows 98/98SE is not supported. Windows 7 64 Bit is supported since version 7.6.1.

What is Pseudo-FSK/Pseudo-CW?

For 'real' FSK keying one would normally require a true UART chip in the computer (parallel to serial converter, COM-Port). With a virtual COM port such a device is simulated by the USB driver, but only with some problems. Depending on the load of the computer the timing of keying can vary (jitter) or be delayed (latency). This leads to not very clean telegraphy keying. With RTTY/FSK the characters might be illegible on the receiving side due to timing errors.

Now some multi mode programs (e.g. fldigi) have found a good solution to this USB driver issue. Instead of toggling a handshake line of the virtual comport, an audio signal is sent (or not) to the right channel of the soundcard output. An additional hardware decoder within the USB-III interface detects the presence or absence of the tone and uses this information to key the FSK or CW line to the radio.

This leads to a much more precise timing with FSK and CW. Especially when using high speed telegraphy or QSK this is very beneficial. When using RTTY/FSK you can be sure that all characters are sent with the proper and consistent baudrate.

Of course the radio must support FSK keying to use this function with RTTY. When using AFSK this problem does not exist.

• No COM or LPT port necessary, just one USB port
• Complete "Computer <-> Radio" electrical isolation
• Integrated computer control port for all radios CI-V, FIF-232, IF-232, RS-232
• Squelch input for signaling to computer
• No external power adapter required
• Strong RFI immunity
• Quick change connectors
• Two controls for TX and RX audio
• Pseudo-FSK, Pseudo-CW keying for certain programs (fldigi)
• LEDs for easy visual feedback of CAT, CW, PTT, SQL
• Metal/Aluminum case, powder coated and silk screened
• Free, time unlimited firmware/software upgrades via internet

• USB: USB 2.0 Full speed , USB 1.1 compatible
• CAT RXD, TXD, max. 57600 Bd
• CW: open collector, driven from DTR, max 30V/400mA
• PTT: open collector, driven from RTS, max 30V/400mA
• FSK: open collector, driven from DTR (requires EXTFSK from MMTTY. or pseudo FSK from fldigi)
• SQL input: close to ground or high (two inputs) to activate. Wired to CTS
• Size: 103mm x 28mm x 101mm (BxHxT)
• Weight: 220 gr (without cables)

• USB-Interface II
• CD-ROM with driver software, manual
• USB cable (A/B)

Important: Cable to radio needs to be ordered separately!

USB-III Interface

USB-III Interface

DB15-IC8 DB15-IC13 DB15-TS6 DB15-TS9 DB15-TSMINI6 DB15-FT450 DB15-FTMINI8 DB15-FT736 DB15-FT847 DB15-FT890 DB15-FT920 DB15-FT950 DB15-FT990 DB15-FT1000M DB15-FT1000D DB15-TT-OM DB15-EL-K2

List of cables for microHAM "digiKEYER", "USB-2" and "USB-III" interfaces

DigiKEYER List of cables and schematics

Other cables for Elecraft, TenTec etc. on request.