Built and tested a NinoTNC N9600A3

Recently I bought a PCB, ordered the components, and built myself a NinoTNC N9600A3. Just curious how it would work and perform compared to several old TNCs and the more modern soundcard modem software.

The building instructions are very clear and comprehensive. Anyone with a little bit of soldering skills can easily build one. After building and some basic testing I noticed the firmware was a bit outdated already. Nino is releasing updated versions fast it seems. Therefore I’ve updated the version to the latest version available at the time of building (2.51).

Now it was time to do some testing and comparison for operating on CB (1200bps AFSK only!). It seems to perform very average overall but is slightly performing less with weaker / more noisy signals compared to some old-skool TNCs with a TCM3105 or AM7910. As expected it’s nowhere near the RX decoding results you get with a piece of soundcard modem software like Direwolf (1.5) or UZ7HO’s Soundmodem (1.0.5).

The NinoTNC also seems to suffer a bit due to RF getting into the dsPIC microcontroller. Placing the (optional) inductors didn’t have a satisfying effect and on a regular basis the dsPIC totally ‘stalled’ or the program counter was getting corrupt somehow. I noticed the PCB design doesn’t have any groundplanes I thought incorrectly the PCB design didn’t have any groundplanes but that doesn’t seem to be the case. Using a metal case, properly connected to the NinoTNC’s ground was my best option to get rid of this problem. I’ve just placed it for testing in a small metal case and didn’t see the dsPIC ‘stall’ a single time again.

It was a nice little project to build and test but I don’t think I’m going to use the NinoTNC a lot. More like another ‘nice to have TNC’ for my collection.

2 thoughts on “Built and tested a NinoTNC N9600A3

  1. Dave,
    The NinoTNC is a 4-layer board with a flooded ground-plane.
    As of late October there is an improved AX.25 receiver, but v2.51 should perform better than the TCM3105 modem. Also AGC allows a much wider range of voltages than the TCM3105. I don’t understand why it isn’t working for you. Please try v2.81. What bootloader mechanism are you using? 2.81 has a nice receive volume alignment feature. The CRC-Bad LED flickers if the receive audio is out of range. You can lower squelch, turn up the volume and then set the volume to the maximum where the LED does not flicker.
    Have you checked out the Operation and History documents on the web site? http://tarpn.net/d
    Sorry for the trouble — de Tadd KA2DEW

    1. Hi Tadd,

      I just rectified the statement about the groundplanes. The n9600a seems to be (very) sensitive for EMI/RFI and I didn’t see groundplanes on top and bottom layer. Only saw just traces without being enclosed by a groundplane at the top and bottom.

      Although AGC allows a wider range of voltages I noticed it seems to have more trouble decoding less clean / noisy audio from weaker signals compared to a TCM3105 based TNC. With more clean signals it’s performing very similar as most TNC2 type TNCs with a TCM3105. Overall performance with real usage seems to be very average from what I’ve seen. Maybe I’ll do some controlled testing and measurements with the n9600a and several other modems one day, but for now it was just a build for fun and to have one in my collection of modems.

      I will give the 2.81 firmware a try with the RX volume alignment feature. For upgrading the firmware I’ve used the Python script from Github at the time.
      The Operation and History documents I’m checking frequently, just to see if there’s done some improvement on the RX part.

      73! Dave

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