What is SUCCI

SUCCI stands for "Simple USB CAT & CW Interface". The idea for SUCCI was born at the time I realized that although I have the Microham MK2R+ orchestrating my home station, I was completely unprepared for field operation with my beloved FT-897. Of course, I could bring my MK2R on the field .. but .. you know .. such expensive items are usually the first to attract either a ball of mud or a falling hammer. The idea to have relatively cheap, portable, USB-based device that uses as much as possible pins of the serial port was born and converted to device in the beginning of 2012. As of 2013, tens of HAMs have integrated and adopted SUCCI in their setups and thanks to their feedback, the unit evolved to reach its 2nd version - SUCCIv2. In addition to the existing TTL version (now renamed to SUCCI-T), an RS-232 (SUCCI-R) version of the board was born in the middle of 2013.


SUCCI is not rich in features, but this is actually the idea behind - simple and (I believe) cheap device that you could throw wherever you want. A list of the features follows:


SUCCI-T specific features

  • CAT terminal for radios with TTL-level based control interface that utilizes RF blocking circuit

  • Jumper selectable single-wire (Icom CI-V) or double-wire (Yaesu/Kenwood style) CAT terminal output

  • Hardcoded Icom/Yaesu or Kenwood CAT mode

SUCCI-R specific features

  • CAT terminal for radios with RS-232 level based control interface that utilizes RF blocking circuit

Common features

  • USB interface towards PC/laptop with standard USB type B connector

  • Optoisolated CW and PTT open collector outputs connected to respectively the DTR and RTS lines

  • FootSwitch (FS) input with RF blocking circuit activating the DSR line

  • LED-based indicators for CAT, CW and PTT activity

Supported radios

CW and PTT functions are supported on virtually all radios that switch less than +70VDC and 30mA on their CW and PTT inputs, but not more than 100mW per input. You radio should be supported in case it was produced during the last 25 years.

Computer control (a.k.a. CAT) is supported on the following radios:

SUCCI-T supported radios

  • all Icom transceivers with CI-V interface

  • Yaesu models: FT-100, FT-817, FT-840, FT-857, FT-890, FT-897, FT-900, FT-990, FT-1000(D)

  • Kenwood models: TS-50, TS-450, TS-690, TS-850, TS-950

  • Other radios that utilize TTL voltage levels for computer control might be supported as well, please get in touch for clarifications.

SUCCI-R supported radios

  • Elecraft models: K2, K3, KX3

  • Yaesu models: FT-450(D), FT-847, FT-950, FT-1000MP, FT-1000MPmarkV, FT-2000

  • Kenwood models: TS-480, TS-570, TS-590, TS-870

  • Other radios that utilize RS-232 voltage levels for computer control might be supported as well, please get in touch for clarifications.

Theory of operation

The heart of SUCCIv2 is the well-recognized FTDI USB to UART chip FT-232RL. There are many reasons for using this specific chip, to name few of them:

  • stable drivers

  • driver availability for different operating systems - Windows, MacOS, Linux

  • adopted and recommended by most of the HAM radio software developers

  • easy to find in my own country, so I can speed up manufacturing process

The serial terminals of the chip are then connected to the respective outputs with very few supporting elements - current-limiting resistors for the CAT, TTL to RS-232 level converter (for the -R model), LC-based RFI filters for both CAT and FootSwitch terminals, optocouplers for CW and PTT isolation (in case you are going to use it on a radio with high voltage levels on these inputs). In addition to that, LEDs for CAT, CW and PTT activity monitoring are placed so you always know whether CW/PTT are going out of the USB to UART module or if your computer communicates with your transceiver. This helps you to troubleshoot PC or optocoupler/interface issues. Eventually, all the terminals are available on standard and easy to use RCA cinch and 3.5mm stereo jack plugs.

Connecting SUCCI

Connection to your PC is established through the board's USB connector. In case your computer fails to automatically install the respective drivers, these can be obtained from the following link.

Your radio's CW key input should be connected to the red RCA jack. My personal choice goes for standard stereo jack to red & white cinch cable, the tip of the red cinch on the cable is (usually) terminated on the jack's tip and the white cinch is either isolated or removed.

If your radio has cinch as PTT input, standard cinch-cinch audio cable can be used for this connection as well. If not - you'll have to do some soldering. White-coloured cinch connectors are recommended in order to keep the color scheme.

Footswitch input (the yellow one) is active when shortened, so normally it is expected that your footswitch has N.O. contact and a (yellow) cinch connector.

Important note on connecting SUCCI boards to your transceiver for radio control!!! Please read carefully!!!

Radio control (a.k.a. CAT) is terminated on a 3.5mm stereo jack for both SUCCI-T and SUCCI-R models. Please note that voltage levels between the -T and -R version differ substantially!!! Connecting improper SUCCI to your transceiver may damage both the transceiver and the board. If in doubt - please message me through the contact form!

SUCCI-T CAT connection

SUCCI-T boards make all Icom owners' life easier because (again) standard 3.5mm jack to 3.5mm jack audio cable fits perfect. Non-Icom owners should exercise their soldering skills. Selection for Icom/Non-Icom radio is done by JP2 on the board with positions 1-2 for Icom and 2-3 for non-Icom. Please note that boards that support CAT for Kenwood tranceivers are factory programmed in a way that makes it impossible to use them for Icom/Yaesu radios. Still, the jumper settings for these boards are non-Icom.

SUCCI-R CAT connection

SUCCI-R boards make KX3 owners' life easier because (again) standard 3.5mm stereo jack to 3.5mm stereo jack audio cable fits perfect. Soldering is needed to cover all other cases.

User Guide & Schematic

Both User Guide and Schematic are available as PDFs at the files section on the bottom of the page.

Obtaining SUCCI

As of beginning of 2021 SUCCI is no longer produced. Still this page will live for reference.