External memory buttons
these are used to playback the recorded audio, CW or RTTY messages.
I followed the design given in the ICOM manual however in my case I brought the connections through to an inline 8 pin socket, so that the unit can be connected in line with the microphone.
I also added a 0.5 MFd blocking capacitor in the plug to the rig so that I can use my dynamic microphone with the IC-7300 without it being damaged by the phantom power that ICOM need for their cheap ceramic insert microphone.
Note: When recording the voice key audio clips, (see chapter 7 in the full manual) you need to use the ICOM supplied microphone to make the recordings, other (e.g. better, Dynamic) microphones will not work with the recording software. Eight audio clips can be stored in the IC-7300 (onto the SD Card you supplied) but only the first four can be played using the external keypad.