AIOC Fix DigiPi v1.9-4 (Kenwood HT)

[Andrew Strojny III]

Hello All,

First off, I wanted to say thank you to Craig - KM6LYW for such a great contribution to Amateur Radio!

I had some issues getting my setup working and wanted to post my steps to get the NA6D AIOC working on DigiRig v1.9-4. This is my first post and I'm a linux novice (just saying). I just figured I would document my problem and what I modified to the .conf files to get it working in case someone else ever experiences the same thing. I wanted to include screenshots and what my process was to get it running so that others didn't have to search around. :)

Happy Hamming!

-73-

Andy - KC8YFO

Goal

* Portable APRS iGate that I could use with my small HT as a base station for reception from my HT around wherever I happen to be where APRS coverage may be limited.

Hardware

* Raspberry Pi 4B

* NA6D AIOC plugged into the top left USB port on the pi.

* USB-C Cable with Ferrite Beads on each end

* Kenwood TH-F6A HT

Problem

* Preface: When running initialization I selected AIOC for the interface.

* Audio in always worked fine and Packetlog showed the incoming packets from my sending radio (Kenwood TH-D75A) as well as other local traffic but when it would transmit (testing using webchat) it would latch PTT to transmit and continually transmit and no audio would come through when using the AIOC located at /dev/hidraw0 3.

SysInfo

Here was a sample Packetlog on startup

Fix

Changes made to direwolf.tnc.conf | direwolf.digipeater.conf | direwolf.node.conf | direwolf.winlink.conf | direwolf.tracker.conf | direwolf.tnc300b.conf

1. I used putty to sudo remount, then used WinSCP to copy the files off of that I could easily edit them in notepad and keep the originals, saved the modified .conf files to a different folder with the same names and dragged them back to the device. Afterwords, in putty ran sudo ./saveconfigs.sh then sudo reboot
2. Bound Dire Wolf audio explicitly to the AIOC USB card by adding to each .conf file:
   ADEVICE plughw:0,0 plughw:0,0
   so that the TX/RX audio uses the same USB interface instead of the system “default.”
3. Switched PTT control to the CM108 GPIO by setting PTT CM108 3 (non‑inverted) so the AIOC asserts PTT correctly without latching.
   1. I accidentally had a "-3" which was inverting the PTT signal....so watch that.
4. Commented out the prior DCD line to avoid contention and because CM108 GPIO is not used as a DCD input in this setup.
5. On the radio side, used the TH‑F6A SP/MIC jack mode (Menu 9 “SP/MIC”), squelch open, and battery saver off so Dire Wolf receives constant audio and controls PTT/audio fully.

Modified code that is applied in the correct section for each .conf file listed above (this is from the direwolf.tnc.conf one)

Result

After these changes, startup showed the AIOC device name instead of “default,” and PTT asserted only during frames with audible 1200‑baud AFSK, confirming correct device binding. PTT and audio transmit worked perfectly.

In action in Billings, MT

[Andrew Strojny III]

Quick follow up. Has anyone had any issues with ground looping with the AIOC?

[pd2ch 2CH]

Yes, specially with the antenna mounted direct on the HT. Best use a extension coax to position your antenne a few meters away from the HT. (In my case, 1 meter did the trick).

My best 10cts,

PD2CH 

Op vrijdag 3 oktober 2025 om 17:27:58 UTC+2 schreef apstr...@gmail.com:

[Andrew Strojny III]

In my case I tried it at home with a magmount. The minute I plugged the interface in the s meter goes to 7. If I keep everything on the battery as a common ground it's a 3. 

[Doug Reed, N0NAS.]

The DigiRig is a similar common ground interface and they suggest using a USB Isolator if ground loops are a problem. In the case of the S-meter jumping, I'd think that might be a RF noise problem instead. The common ground would conduct RF noise really well. OTOH, the lower noise level on battery might indicate the noise is coming from the power line connection? If it is conductive RF you may need multiple turns of the USB cable through a clamp ferrite to reduce the level. You could possibly confirm the RF noise issue by listening to a weak (distant) repeater then connecting the interface and see if the noise on the computer audio is substantially worse.  You will be switching from the HT speaker to the computer speaker, but if the repeater audio gets noisier or the repeater drops out then you have proven you have an RF noise issue.