USB Programming Cable for Tait TM8110 PMR Radios

Making a USB Programming Cable for Tait TM8000 series PMR Radios to use as Ham Radio repeaters

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Date 08 September 2022
Views 7,165
Time to read 5 minutes read

We were recently asked if we could help with the setup of a local AllStar Link radio repeater for our area.

AllStar Link is a radio repeater system which uses Voice over Internet Protocol to allow distant radio hams/amateurs to communicate via a local access repeater. More details about AllStar Link can be found at https://www.allstarlink.org.

The AllStar Link software runs on a Raspberry Pi or other compatible hardware and uses a modified CM108 USB sound card as an interface to the radio.

A Tait TM8110 PMR Radio was purchased for the repeater from a local ham radio rally.

Radio
Radio

The Tait TM8110 radios have a 6-pin RJ45 connector on the front panel for the microphone and an auxiliary connector on the rear panel using a 15-pin D-Sub connector.

Programming Cable

There are commercial programming cables available for the Tait radios but the only models we could find were in America and had expensive shipping charges.

The radio uses a UART connection at 3.3V for programming and we initially tried to connect the radio to the computer using our USB MultiComms interface via the front RJ45 connector.

Prototype testing
Prototype testing

We were unable to get any response from the radio and after further investigation, we found that the Tait radios use an inverted UART signal.

After adding a logic inverter via a breadboard, we were able to communicate with the radio and the programming software.

Making a USB Programming Adapter

Once we knew that we could program the radio, Andrew designed a very compact USB to Serial interface with logic inverters and ordered the PCBs. After a couple of weeks, the new boards arrived, and the components were soldered to the board.

The interface uses an FTDI FT230X chip and a pair of SN74LVC1G04DBVR inverter chips to invert the output to the 3.3V logic the radio requires.

PCB
Finished PCB

Bill of Materials

Name / Part No Value / Description Quantity RefDes
CAP_0603 47pF 6 C1, C2, C3, C4, C5, C6
TX Red LED 1 D1
RX Red LED 1 D2
48037-0001 Molex USB Connector 1 J1
MI0805K601R-10 FERRITE BEAD 600 OHM 0805 1LN 1 L1
RES_0603 27R 4 R1, R2, R5, R6
SN74LVC1G04DBVR Texas Instruments Inverter 2 U1, U3
FT230X FTDI USB Full Speed to Basic UART IC 1 U2
Radio
Schematic

The PCB and schematic can be downloaded in Diptrace format from github.com/briandorey/USB-Programming-Cable-for-Tait-TM8110-PMR-Radios

The pinout for the RJ45 connector is:

Pin Signal name Description Signal Type
1 PRG_RX_AUD Receive audio output Analog
2 +13V8 Power supply output. Switched off when radio body is switched off. Power
3 PRG_TXD Asynchronous serial port - Transmit data. 3.3V CMOS
4 PRG_PTT PTT input from microphone. Also carries hookswitch signal. Digital
5 PRG_MIC_AUD Fist microphone audio input. Analog
6 AGND Analog ground Ground
7 PRG_RXD Asynchronous serial port - Receive data. 3.3V CMOS
8 PRG_ON_OFF Hardware power on/software-power off input. Active low. Digital

USB Sound Card: www.amazon.co.uk

USB Sound Card Modifications: allstarsetup.com/how-to-modify-a-cm108-for-allstar/

Tait TM8100 Series Programming Software: www.radiotronics.co.uk/tait-tm8100-series-programming-software

Hamvoip software: hamvoip.org

18 Comments

  • User Image

    Robin

    31 October 2022 at 11:34 am

    Is there any chance to use PL2303 or CH340 for this schematic?

    • User Image

      Brian

      31 October 2022 at 12:55 pm

      Either of these chips should work for the UART communications

  • User Image

    Petir

    02 November 2022 at 11:58 pm

    Would you please to tell me the pin of TX and RX in J3?

    • User Image

      Brian

      03 November 2022 at 9:19 am

      Hello Petir

      The pins are:

      1 - TX
      2 - RX
      3 - GND

  • User Image

    Petir

    16 November 2022 at 12:05 am

    I'm sorry that I am mistakenly mention in my question before.

    What I mean is the position of TX, RX and Ground in RJ45 pin of Tait mic's pinout

    Thank you

    • User Image

      Brian

      16 November 2022 at 10:37 am

      Hello Petir

      The microphone connector pinout is listed above

  • User Image

    Petir

    04 December 2022 at 7:19 am

    Well

    Finally, it works.

    Thank you

  • User Image

    Mohamed

    24 August 2023 at 2:26 pm

    I need Tait 8100 Software V3.09, Please help me

  • User Image

    Petir

    28 February 2024 at 10:26 pm

    Thank you. I can make the cable for tait from pl2303 and ch340 module

  • User Image

    Andreas

    09 March 2024 at 9:12 pm

    Can you provide a new link for the programming software?

    • User Image

      Brian

      09 March 2024 at 9:12 pm

      The software link is at the end of the post

  • User Image

    Pete, GW8UXL

    27 March 2024 at 11:43 am

    Hi All,
    Here is a much simpler method of making a programmer for the Tait T2000 and TM8000 series radio, I wrote an article for this programmer a few years back for a well known ham-radio magazine. Anyway I hope it helps anyone wanting to make their own programming lead, I like to make all of my own.
    If you use a 6-Pin plug it will, fit and program both the T2000 and TM8000 radios.
    Good luck and have fun guys.
    Pete, G8UXL /GW8UXL (QTHR QRZ.com).

    For reasons I do not understand I can’t post the article, if any one would like the article please email me, my address is on QRZ.COM
    (Mar 24).

  • User Image

    Pete, GW8UXL

    27 March 2024 at 11:43 am

    Hi Again,
    Sorry I just re-read the post, properly this time! and realised my programmer may not be relevant for this purpose, sorry about that.
    Thought I may be helping the less technically experienced build their own programming lead for the Tait T2000 & TM8000.
    Pete. GW8UXL. /G8UXL.

  • User Image

    sergio SA

    03 June 2024 at 10:32 pm

    ok

  • User Image

    Robert

    21 July 2024 at 8:48 am

    where can i buy the PCB from please?

    • User Image

      Brian

      21 July 2024 at 8:49 am

      There is a link in the post for the PCB files and you can then order them from any pcb manufacturer

  • User Image

    Ali Abbas

    04 April 2025 at 4:47 pm

    How can i get programming software for my tait tm8110? i have searched a lot but i am not able to find it.

  • User Image

    Moisés

    05 June 2025 at 9:49 am

    Muchas gracias por los aportes, llevo varios años intentando programar este radio y todavía no lo consigo.Pete GW8UXL podrías ayudarme por favor


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