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) → 3.5mm TRRS tip (RIG_AFOUT)
2.5mm TRS tip (Mic/PTT) → ring1 (RIG_AFIN)
3.5mm TRS sleeve (Ground) → 3.5mm TRRS sleeve (GND)

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

Ground between transceiver connectors (optional)
3.5mm TRS sleeve (Ground) → 2.5mm TRS sleeve (Ground)

Thank you very much for the pinout. Just to confirm, on the line that reads “3.5mm TRRS ring 2 (PTT) → 3.9K → 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.

1 Like


Thank you for the quick shipping on the prototype cable. It arrived Saturday and I started testing yesterday with the Icom T-70A. So far it appears to be working well. Today I am going to try a Winlink connection between this HT and another radio. Will continue to update … is there anything specific that you are looking for as far as an evaluation?


1 Like

Thank you for the confirmation. If you can get audio in and out and the software keys up the radio then we are all set. What works for one digital mode will work for the rest. Please share a few pics of the working setup if you have a moment.

I’ll get this cable on the order. General availability at some point later this year.

1 Like

Denis et al,

I have attached three photos of the prototype cable in use. The first just shows the cable connecting the Icom T70A to the digirig Audio port and then to the computer.

The second shows the radio attempting to connect to a “local” Winlink packet station by using the SoundModem by UZ7HO software TNC.

The third picture captures the computer and interface keying up the radio as indicated by the bar at the bottom of the screen.

I still have some settings to manipulate to get everything working right in Winlink and SoundModem. Currently, I can connect to another Winlink station but it drops the connection before transferring data. End goal is to use the HT connected to a computer to send a Winlink message through another radio set up for crossband repeat to a Winlink Gateway station. Use case is for EMCOMM operations where the operator is set up inside a building such as a shelter, POD (Point of Distribution), etc. but there is no access to the roof to mount antennas. This will allow the operator to transmit from within the building to a go-box outside and send that message to another station or Winlink gateway via the crossband repeater function on the outside go-box.

Rob Hiltner


Thank you for the confirmation. I’ll work on adding this cable to the store.
Anybody interested, please signup for the email list on the website to receive availability updates.

1 Like

Hi Denis,

I am looking to connect my IC-V85 and ID-52, by the look they seem to have the same plug, can you advise if they have the same pinout too? I will for sure buy some from you if have them.


Not finding any pinout info to compare side-to-side these two radios. Looking at ebay listings for speaker mics there isn’t a single listing that claimed the support for both. The two compatibility groups appear to be:

  • IC-DPR3, IP100H, IP500H, SK-2000, ID-51E and ID-31E
  • IC-F3, IC-F10, IC-F11, IC-F12, IC-F14, IC-F15, IC-F16, IC-F4, IC-F20, IC-F21, IC-F22, IC-F24, IC-F25, IC-F26, IC-F33, IC-F34, IC-F43, IC-F44, IC-F3000, IC-F3001, IC-F3002, IC-F3003, IC-F3011, IC-F4000, IC-F4001, IC-F4002, IC-F4003, IC-F4011, IC-F3021, IC-F3022, IC-F3023, IC-F3026, IC-F4021, IC-F4022, IC-F4023, IC-F4026, IC-F3031, IC-F3101, IC-F4031, IC-F4101, IC-V8, IC-V80, IC-V80E, IC-V82, IC-V85

From this post we know that the cable discussed here should at least fit the first group.
Based on my low-grade analysis of the pictures, the spacing of the connector appears to be the same.

Pinout might be same of different. Do you happen to have a speaker mic for your IC-V85? We can derive the pinout by peeking inside and doing some continuity testing on it.

[UPDATE] The cable has Baofeng programming pinout :frowning:

[ORIGINAL]Unfortunately I dont, all I have is one of those 8in1 programming cables which one fits the plug, I will try to connect it tonight and give it a shot. I will keep you posted.

The pinout and cable works fine with the ICOM IC-V85.

1 Like

Any video or photos of how you put the 0805 size surface mounted resistor on/in the cable?

Kevin JJ1PJI

In the prototype I build I ended up using TH resistor because there was enough room for it inside screw-on sleeve. I’ll take picture/video if I end up building another cable.

1 Like

The cable is now available in store: