Version 1.21

Parts list



C1 and R6 are optional components. Whether you need them or not depends from the type of microphone you want to connect to your Icom radio through the 3.5mm jack. C1 for example is needed when you want to connect a dynamic microphone. It’s not needed when you use an electret microphone.

R6 is needed when you need “phantom power” between 0v and 8v. (

You don’t need to install these components if you already can use your microphone directly with your rig.

Version 1.00

Parts list


Version 1.20

Parts list


What is it, and why would you need it?

A (voice, CW, RTTY) keyer is a tool to record and play back messages. When you are calling CQ, you don’t have to endlessly speak or send morse, the keyer can do that for you.

Many Icom radio’s like the IC-7300 have a built in voice keyer with 8 memory slots. However, you can only activate these via the touchscreen when you are in the keyer menu (obviously).
This keyer menu takes up 50% of the display, and prevents you from viewing other interesting screens, such as the extended waterfall or the audioscope.

With an external keypad we can recall up to 4 out of the 8 memory slots, without having the keyer menu on display. An additional advantage of an external keypad is that you can install it in a spot that is best accessible to you. In case of a contest e.g.: just next to your PC keyboard.

Connector Cable

For information about the connector cable, check out this blogpost: Icom External Keypad Connector Cable


Creative Commons License
This work is licensed under a Creative Commons Attribution-NonCommercial-NoDerivatives 4.0 International License.

Need help?

If you have any questions regarding the design, or how you can manufacture the PCB, feel free to let me know in the comments, or send me an email (can be found on
Interested in having an external keypad for your Icom radio, but you are not in the possibility to make it yourself, for whatever reason: don’t hesitate to send me an email.

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2 Replies to “Icom External Keypad Project”

  • Hello, in version 1.21, Resistor R6 and capacitor C1 What values do they have to have?
    What is the purpose of these two components?

  • Hello Juan Carlos,

    The C1 capacitor blocks the voltage to the mic element. This can be needed when you want to connect a dynamic microphone to your Icom. You can find more info about this on the website of Heil Sound. (

    The R6 resistor is foreseen in case you want to connect an electret microphone that needs some voltage between 0V and 8V. The value of the resistor needs to be chosen based on the voltage you need.

    Both C1 and R6 are optional components that are specific to the microphone you want to connect via the 3.5mm jack on the keyboard. They both can be bypassed by setting jumpers (or not).

    If you only want to connect the keyboard between your Icom mic (or any mic that you already can connect directly to your rig) you dont need these two components.
    And you also don’t need them if you use a condenser mic like this for example:

    73 de ON5IA

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