ANNOUNCING: MorttySP – Speed Pot Accessory for the Mortty Kit

Click HERE for Photos and Details


Morse Code and RTTY Keyer

Mortty is a Do-It-Yourself construction project that provides a miniature enclosure and a computing platform for K0SM’s TinyFSK RTTY Keyer software or K3NG’s CW Keyer software. It optionally can be configured to run W1HKJ’s nanoIO software using fldigi.

Unlike the full-featured – and more expensive – hardware solutions for CW and RTTY keying that are widely available to amateurs, Mortty is an inexpensive minimalist solution that depends upon the configuration and control features incorporated in popular logging and control programs. This tiny box measures only 2 inches long and 1 inch square (50mm by 25mm). Mortty has two input connectors (a microUSB jack to connect a computer and a 3.5mm jack to connect a CW paddle) and one output connector (a 3.5mm jack that provides PTT, CW and FSK signals to your transceiver).

Designed by N8AR and K8UT, Mortty is available as a complete parts kit, or you can use this guide to build your own from “scratch.”

Key Features

  • Inexpensive, off-the-shelf, readily available components (except for the Mortty board itself)
  • Small, portable, USB-powered
  • Rugged RFI-resistant metal enclosure
  • CW Keyer emulates the widely supported Winkeyer protocol
  • RTTY FSK keying via widely supported TinyFSK protocol
  • Optional Dual-Mode Sketch CW and RTTY operation using nanoIO and fldigi
  • Construction requires only common hamshack tools

Setting Expectations

  • What’s missing from this miniature design?
    • For CW – No speed potentiometer, no macro pushbuttons, no monitor speaker
      • NEW! See MorttySP accessory if you want a CW Speed Pot on your Mortty
  • Standard Mortty v3 Single-Mode Sketch configuration, CW or FSK – but not both?
    • Mortty operates either CW Keyer by K3NG or TinyFSK by K0SM
    • Switching between modes involves: closing the logging program, unplugging the Mortty output cable, launching the Arduino IDE, uploading the desired sketch (CW or RTTY); re-inserting the output cable
      • Elapsed time for switching modes – about one minute
      • Maybe you should build two Morttys? 😉
  • Optional Mortty v3 Dual-Mode Sketch configuration using nanoIO and fldigi – both CW and FSK
    • Optional assembly configuration provides for separate PTT, CW and RTTY outputs (three wires)
    • Requires using nanoIO by W1HJK with fldigi for CW and RTTY operation
    • Switching between modes accomplished via menu selections in fldigi
  • Degree of mechanical difficulty – low (if you use the 3D printed plastic end caps)
    • The Mortty board fits very tight in the metal enclosure. You may need a file or sandpaper to adjust the Mortty board for a snug fit in the case
    • If you decide to use the metal end caps, you will need to make five holes in the enclosure end caps
      • Use this documentation or the plastic end caps as a drill guide
      • Drill four round holes for paddle input, keyed output, and two LEDs
      • Drill / notch / file one oblong hole for the Arduino Nano USB connector
  • Degree of soldering difficulty – medium
    • To achieve Mortty’s miniaturization, the components are tightly packed on the circuit board
    • There is only one surface mount part, the paddle jack. Its solder pads are as large as standard circuit board components and will be no more difficult than soldering the other components
    • You will need some type of circuit board holder and parts stabilizer to assist in soldering parts to the small Mortty board (small vice, tweezers, hemostats?)
  • Degree of computer expertise – low
    • No programming required
    • The are many excellent resources on the Internet to assist you in loading the proper drivers for the Arduino Nano and uploading the desired sketch onto the board
    • Based on your PayPal order, we will preload the Arduino Nano with your desired sketch (TinyFSK, CW Keyer or nanoIO)
Mortty v3 is not the same As Winkey v3
Mortty v3 was released in July of 2018, and uses K3NG’s CW Keyer sketch. CW Keyer emulates Winkey v2.3 operation and is a CW-only device.

In March of 2019 K1EL released Winkey v3, which is a dual-mode CW and RTTY Winkeyer. Mortty v3 does not emulate Winkey v3 dual-mode CW and RTTY operation. (see nanoIO and fldigi if you need dual-mode operation from a single Nano sketch)

Mortty v3 in its final assembly stage

Deciding Which Sketch You Need

Mortty’s behavior is determined by the program (“sketch” in Arduino-speak) installed on Mortty’s Arduino Nano. Changing sketches is not difficult, and the process is described in an on-line video on the website. BUT… to simplify your Mortty assembly, the developers will pre-install your preferred sketch before sending you the kit. After building your kit, you can always change the sketch at a later date should you decide to do so.

The CW Keyer sketch delivers a very faithful emulation of the popular and widely supported Winkeyer version 2.3. If you are a CW operator and want an excellent CW keyer (but no RTTY), this is the sketch you want.

The TinyFSK RTTY sketch is a time-proven RTTY modulator and is supported by most of the popular RTTY software and logging programs. If you want to operate accurately timed FSK RTTY (but no CW) and use N1MM, WriteLog, DXLab, Logger32, DX4WIN, MMTTY, 2Tone, fldigi… and many others, you want the TinyFSK sketch.

The fldigi nanoIO sketch offers something that the other two cannot – the ability to switch between RTTY and CW modes by a simple menu choice in fldigi. This requires, of course,  that you have chosen the fldigi software as your digital program. If you are an fldigi user; if you want to be able to switch instantaneously between RTTY and CW, then you will want the nanoIO sketch. Furthermore, if you do not use the Windows Operating System, fldigi’s multi-platform software for Mac and Linux users will support Mortty in a non-Windows world.

Differences Between Mortty Sketches

Mortty v3 uses a 4 conductor output jack.

With the traditional one-at-a-time CW or RTTY sketches (TinyFSK and CW Keyer), three of those conductors are GROUND, KEY/FSK and PTT. The fourth conductor is used internally to “see” whether the user has an output cable inserted. If the output cable is inserted, Mortty launches in Operate mode – ready to listen to a logging program and talk to a radio. If the output cable is not inserted, Mortty launches in Program mode and is listening for a sketch upload from the Arduino IDE. The advantage to the user is that they can change sketches by unplugging the cable, uploading a new sketch, and plugging the cable back in. No disassembly required.   The nanoIO sketch supports both CW and RTTY keying. With nanoIO, Mortty now requires all four conductors for outputs: GROUND, RTTY FSK, CW KEY and PTT. A nanoIO Mortty loses the ability to use that fourth conductor to “see” if a cable is plugged in, and thus loses the ability to switch from Operate to Program mode by simply unplugging the output cable. Furthermore, we need to reroute some signals on the Mortty printed circuit board to get the RTTY and CW signals to the right conductors. As a result:

  1. Page 20 of the Mortty manual describes the mods you need to make to the Mortty PCB: cut one trace, add two solder bridges. Simple. Easy.
  2. To put a nanoIO Mortty in Program mode to change sketches (which should be a rare event with nanoIO because it already supports both modes) you must disassemble Mortty and separate the Arduino board from the Mortty board
  3. If you decide to revert to the CW Keyer or TinyFSK sketch, you will need different cables and a soldering iron to un-solder the two bridges and re-solder the initial trace

Different Mortty Versions Use Different Sketch Upload Methods

Arduino IDE Settings

Don’t forget to set the IDE >Tools menu for Board = “Arduino Nano,” Processor = “ATmega328p (old Bootloader),” and Port = (PC USB port) – before you compile and upload to Mortty!

  • If you have a newer Mortty v3 running the CW Key or TinyFSK sketch, you can switch between Operate and Program mode by simply unplugging the cable that goes to the radio. Unplug the cable for Program mode, upload your new sketch; reinsert the cable, and Operate.
  • If you have an older Mortty v2, you must open the case and remove the Program/Operate jumper to install a new sketch in the Nano. Open the case, remove the jumper for Program mode, upload your new sketch; reinstall the jumper, close the case, and Operate.
  • If you have a newer Mortty v3 running the nanoIO dual-mode sketch, you must remove the Nano from the Mortty board to be in Program mode. Open the case, remove the Nano board from the Mortty board, upload your new sketch; reconnect the Nano board to the Mortty board, close the case, and Operate.
  • If you are changing between nanoIO and CW Keyer or TinyFSK operation, see the manual about the necessary hardware changes.

Order Info

The Mortty CW and RTTY Keyer Kit includes all of the items listed in the Assembly Manual Parts List page: the Arduino Nano, the case, the USB cable, the Mortty printed circuit board, and all components to be installed on the Mortty board. You will need a cable to connect to your radio and the tools listed in the Mortty – Assembly manual. Everything else is included in the kit.

IMPORTANT: As a convenience for first-time Arduino users, we pre-load your preferred mode on the Arduino Nano. Please purchase the CW, RTTY, and/or nanoIO versions of the Mortty kit (or kitS – 2 RTTY? 2 CW? one of each?). Of course, you can always replace the installed sketch later using the Arduino IDE.

Purchase and Check-Out


Close-up view of an assembled Mortty v3 circuit board with its 22 components

VERY IMPORTANT: The developers use some creative assembly tricks to squeeze all of Mortty’s features into this small enclosure. Please read and carefully follow the kit instructions in the sequence presented in the manual.

Mortty v3 assembly instructions can be found on the Downloads page HERE

The final version of the previous Mortty v2 assembly instructions is also available on the Downloads page

Mortty v3 kit prior to assembly

In addition to the Assembly Manual, the MP4 Video on the Mortty Downloads page describes (see Errata note below!) the steps necessary to Connect, Download, Install, Compile, and Upload the software associated with Mortty.

Mortty Video Errata
The Mortty Preconfiguration directory described in this video has been deleted from the K3NG CW Keyer download file. You must select which Mortty sketch you want to load by making a simple edit to one of the files. Read the Assembly Instructions for further details.

The website links referenced in the video:

CH341G driver:
K0SM TinyFSK Sketch:
K3NG CW Keyer Sketch :
W1HKJ nanoIO Keyer Sketch:
Arduino IDE Program:


If you have problems assembling or using Mortty, the developers suggest that you look for answers on the Mortty reflector. You do not need to register, or login, or even have an account to search for a solution to your problem. (Although you will need to register if you want to post a new question.) can be found HERE.

The developers:
     Steve N8AR and Larry K8UT

Mortty – Schematic Diagram

A sharper image can be found on the Downloads page  HERE

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