Cable suggestion for Icom IC-T70A


I am looking for a cable suggestion for the Icom T70A HT IC-T70A HD Dual Band FM Transceiver - Features - Icom America. It appears that the default Digirig unit in the store should work for this model radio.

Rob, K4BCN

From the looks of a compatible HM-131 accessory, the connector appears to be a K1 type, similar to that used with Kenwoods and Baofengs, however when I lookup the pinout the online results show it like this:


This is different from Kenwdood/Baofeng:


At this time I don’t have a cable with this ICOM pinout so this would have to be a custom build. It is pretty straightforward though.

Let me know if you need any additional information or post your results if you decide to go for it.

And yes, you can use any Digirig configuration with it.
The configuration only matters if you use Digirig with a CAT enabled radio and connect serial port.

Thank you for the answer! It would be awesome if you had them available because your craftsmanship appears to be much better than my own but I would imagine that your production is based off of demand, not desire.

Going off of the information you provided, I have ordered a HM-46 Handheld Speaker Microphone from Amazon that claims to have the 2AT connector and I have TRRS cables at home that I can modify. So I will just snip the ends off both and do some soldering. Based on the ICOM 2AT diagram, what should the connections to the TRRS look like?

Sounds like a plan. Please report on your progress.

Here’s the pinout:

3.5mm TRS tip (Speaker) β†’ 3.5mm TRRS tip (RIG_AFOUT)
2.5mm TRS tip (Mic/PTT) β†’ ring1 (RIG_AFIN)
3.5mm TRS sleeve (Ground) β†’ 3.5mm TRRS sleeve (GND)

SMD resistor on Digirig connector, capacitor is internal to Digirig and not needed
3.5mm TRRS ring 2 (PTT) β†’ 3.9K β†’ 3.5mm TRRS ring 1 (RIG_AFIN)

Ground between transceiver connectors (optional)
3.5mm TRS sleeve (Ground) β†’ 2.5mm TRS sleeve (Ground)

Thank you very much for the pinout. Just to confirm, on the line that reads β€œ3.5mm TRRS ring 2 (PTT) β†’ 3.9K β†’ 3.5mm TRRS ring 1 (RIG_AFIN)”, the 3.9K is a resistor? If that is correct, is there any specific wattage, tolerance, etc. that I should be looking for? I will need to order this part and looking at the Digi-Key website, I only have 843 choices for a 3.9 kOhms resistor! LOL!!!


It’s by no means a requirement, but to fit on the back side of the connector I would use 0805 size surface mounted resistor.

There is not going to be much current flowing at that resistance level and voltages involved so wattage is not a factor, neither is tolerance. You could stick there 1K and it would still be fine.

Hi K4BCN, Have your parts arrived? Looking forward to seeing your cable.
I am also looking at doing the same for the Icom ID-31Plus.

Good Luck.
Kevin JJ1PJI

Ok, I got a cheap speakermic and built one of these cables:

I’ll try to find an HT to test it locally. Stand by for the report.

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