Converting the Kenwood TKR-820 to use with D-STAR

Converting the Kenwood TKR-820 for use with D-STAR is almost trivial. Here is what you need to do this project.

First you need a TKR-820 (or 720 for VHF) complete with duplexer, antenna, etc., tuned to your repeater pair.  These are currently available on E-Bay (repeater and optionally a duplexer) for around $250-500 as pulled from commercial service. This is a nice little repeater which can run 5W for 100% duty cycle up to around 25W at a decreasing duty cycle. (I’m running around 10 Watts.)

Image of NQMHS with DE-9 plugged In

NQMHS w/DE-9 Plugged-In

Next you need to purchase a node adapter.  I use the “Not Quite So Mini Hot Spot” (NQSMHS) board from ENIcommunications. It comes either as a kit for $80 or pre-built for $110.  I chose the prebuilt version and this post is based on using this version of node adapter.  There are others in the marketplace, but I cannot say if additional work will be required to use them with the TKR-820.

The next order of business is building the cable to go from the NQSMHS to the TKR-820.  The NQSMHS uses a DE-9 plug and the TKR-820 has a great accessory jack which is a Molex 1625-15.  I had a DE-9 socket in the junk box, and purchased the 1625-15PRT, socket and plug, from the local Fry’s Electronics.

DE-9 Image

DE-9 Example

The pinout for the DE-9 is as follows:

1 – Audio to Repeater (Modulator)
2 – Carrier Operated Squelch from Radio (Not actually used with the PA4YBR firmware, but I wire it anyway)
3 – Audio from Repeater (Discriminator Audio)
4 – Key Repeater Transmitter (PTT)
5 – Ground
9 – +12VDC (To power the node adapter, use this instead of USB power for better reliability)

Molex plug image

Molex 1625-15P Example

The Molex 1625-15P (plug) pinout:

Jumper pin 1 to pin 11.  This tells the Repeater it is being controlled by an external controller via the accessory plug (green wire in photo).  Note: if your repeater happens to have an ID-8 module, you will get a CW-ID periodically.  You want to remove or disable it.

Pin 2 is used for ground to the NQSMHS board.
Pin 3 is the modulator input (audio from the NQSMHS)
Pin 4 is the discriminator output (audio to the NQSMHS)
Pin 7 is a +12 VDC source (1 AMP – verify fusing when sourcing)
Pin 8 is the external PTT line
Pin 13 is the carrier operated squelch (COS) also documented as RUS by Kenwood.

Check all of your wiring. (DVRPTR added 9 March 2014)

Signal NQSMHS
DE-9 Pin
DVRPTR V1
Mini-DIN 6
Molex
1625-15P Pin
My
Wire Color
Modulator In 1 1 3 White/Orange
COS/RUS 2 6 13 Orange
Discriminator Out 3 4 4 White/Green
PTT 4 3 8 Blue
Ground 5 2 2 White/Blue
+12V Power 9 - 7 Brown
Jumper - - 1 to 11 Green

Please verify these pinouts against documentation for each device. These work for my configuration, but your repeater may be different. No warranty is expressed or implied. Perform at your own risk.

You will note that no conditioning of lines, such as bypass capacitors, resistors, etc. are included in these instructions. My repeater and board just play together nicely.

This should complete your cable.  If you haven’t guessed I used a piece of CAT-5 cable between the connectors. (Shielded/Stranded cable would be better – I also add some clamp on ferrite cores to this and especially the USB cable.)

Plug the DE-9 into the NQSMHS (as above), and the Molex 1625-15P into the repeater.

Image of TKR-820 with cable plugged In

Molex 1625-15P Plugged into TKR-820

Attach the antenna (or service monitor) and power, adjust the NQSMHS and the modulator for approximately 1.2 Khz deviation.  Adjust power for your use.

Using the firmware tools, insure that transmission is of the proper format (inverted/not inverted) and adjust the NQSMHS for proper detection of data coming from the repeater.

DVAR-Hot-Spot

Screen of DVAR Hotspot in operation

You can now fire up DVAR Hot Spot, with proper configuration.  With a properly registered callsign and configuration you should now be able to link to repeaters, reflectors, and other HotSpots. Note: I tried a netbook to run DVAR with this NQSMHS and it would not key PTT, I think it was a USB drive level. switching to a full size computer solved the problem.

Here is the final product for the NW7DR repeater:

Image of TKR-820 and NQMHS

This is the NW7DR Repeater in operation

My repeater is literally a classic “garage repeater.” The TKR-820 should perform in traditional repeater settings, though for such high RF installations better cabling and packaging of the NQSMHS (shielded) is probably warranted.  The NQSMHS could be mounted internally to the case, pushing the Molex socket inside and running the USB cable out the opening to the controlling computer.

My plan is to move this repeater over to G4ULF’s G2 compatible gateway software after release.  I have a lovely 1U Linux server just waiting to replace the surplus Windows/XP tower currently attached to the NQSMHS.

[UPDATE]

I am currently running Jonathan Naylor’s ircDDBGateway, to support STARNet Digital, along with the GMSK repeater in pcrepeatercontroller.

You can see the Dashboard at NW7DR

[/UPDATE]

May 15th, 2013

I currently recommend the DVRPTR V1 board to drive the TKR-820.

Narrow Band Parts

Component Model
CF-1 CFV 455G V
XF-1 NDK 21F7.5C DN21
R35 1.2K CHIP RESISTOR

Good luck with your conversion!

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39 Responses to “Converting the Kenwood TKR-820 to use with D-STAR”

  1. Well done on a easily understood, and step by step explanation, superb,
    Regards
    David G6OCD GB7HD Repeater Keeper UK.

    • John says:

      David,

      Thanks for your kind words. I hope it will be useful to others who want to attempt a conversion to D-STAR.

      73,

      John

  2. Derek VE5DR VE5SD says:

    Awesome job on the conversion and explanation. I am a newbie on Dstar and want to set-up Dstar on a TKR850 repeater. With the appropriate pinout for my machine, this same set-up should work for our machine. Question, will this set-up work out at a remote location just to pass the Dstar data, voice to other users? At some point we will be adding an internet connection and adding the hotspot, but for now we want to experiment. I have on order the DV-Adapter 2.0 for the Kenwood TS2000, so patiently waiing to start experimentation with that on Dstar. Any help is appreciated! Thanks, Derek – VE5DR

    • K7VE says:

      Hi Derek,

      I’m glad you found my article of use. Yes, with properly selected node adapter and firmware, you should be able use this as a standalone repeater as well, passing anything that is in the DV (Digital Voice, which includes a 1200 bps bit pipe) stream. DUTCH*Star has a pre-release version of their firmware that does a standalone repeater (no computer necessary) and I believe Satoshi’s firmware does as well.

      There are a lot of choices for software to run at the repeater site. I am now on NI-STAR by G4ULF and it is working FB and provides full D-STAR functionality as well as supporting DPLUS and other common applications (D-PRS, ircDDB, etc.) and I would recommend looking at the various options. (See my slides from the DCC here on the blog.)

      As far as Internet connectivity, I am pretty excited about a new family of products from Ubiquiti networks, see NB-5G22 (There are a couple of different models for 5.8 and one for 2.4 ghz), though I haven’t obtained a set yet.

      Keep me advised on your project!

      73 – John

  3. As anyone modded a kendecom / MR4 Series repeater for Dstar I have several new ones with the cat 250 controler installed

    Ernie G4LUE

    • K7VE says:

      Hi Ernie,

      For D-STAR you would throw the CAT-250 controllers away. The control is done by the node adapter, connections are DISC OUT, MOD IN, PTT (and optionally COR).

      This article is a good starting point — let us know if you convert one of the Kendecom repeaters.

      73 – John

  4. K7VE says:

    Some TKR-820s will not move to ham frequencies. Research the repeater you are buying to make sure you can get it on frequency.

  5. HAKAN GUNER -TA2LJ says:

    Dear John,
    I am intend to order two NQSMHS-2 . We have one TKR720(VHF) and one TKR820(VHF) for our club actually working two different sites.
    Can we use those repeaters ”standalone” with NQSMHS-2?
    How can we link those two repeaters in the diffent locations? We also thought about 5.8 GHz linking:) But do we need PCs on repeater locations in this case?? As you imagine we do not prefer this beause of interfence and possible booting problems after power failures.
    If you can propose or advice us what will be the proper solution for linking repeaters?

    Thanks in advance,

    73’s de Hakan GUNER TA2LJ

    • K7VE says:

      Selamlar Hakan GUNER,

      The ability to run “standalone” is dependent on the firmware. I believe that DUTCH*Star (http://www.dutch-star.eu/ — who also sells node adapters) firmware, which is used on the node adapter, has this capability in newer beta code (contact DUTCH*STAR to get the beta – I use it in my repeater). You will need to power the device separately from the USB connection, which is advised regardless of whether you have an on site computer or not (see updated pin out in the article).

      In practical terms, I highly recommend putting a “PC” on site and running either G4ULF’s software or that from G4KLX (his node adapter code is still being debugged). The addition of the “PC” and an Internet connection brings you into the worldwide D-STAR community and can also help with disaster communications. I prefer higher specification boards, but a very low power option people have had success with is the Alix 3D3 (http://www.pcengines.ch/alix3d3.htm) board. It has a compact flash socket and the required software can fit on a 2GB flash drive. With Linux, remote management is quit easy.

      If you are on the network, the repeaters will have to a callsign which is different from the user callsign. If you are running a split site, you will need to bridge the two or have separate callsigns.

      I have not used them, but these look like good Ethernet linking devices: http://www.ubnt.com/nanobridge

      Linking is best done digitally.

      Contact me via email if you need more advice.
      73 DE K7VE

      • HAKAN GUNER says:

        Dear Ken,

        Thank you for your prompt reply. If you can give me your mail I will send you a message,

        Best 73’s de TA2LJ Hakan

  6. Dave Hubbell says:

    Wondering what is needed to narrow band the 820?

    Dave N2KTO

    • K7VE says:

      Hi Dave,

      Narrow banding involves replacing a crystal filter (XF1), a ceramic filter (CF1), and a chip resister (R35). Kits are available, and the best price I have found is for the ZKIT-820NB at http://wirelessrepairsandbatteries.com/zkit-820nb-p605373.html

      (I purchased one only to find a previous owner had already done the modification, so I have a reserve kit.)

      On transmit you will want to pull the deviation down, for example, to +/- 1.2 Khz. for D-STAR.

      If using for D-STAR you will probably also want to remove capacitor C22 and replace with a jumper (Kenwood service note LSB-0208) — I saw an improved reported BER after this modification.

      • John,

        Did my conversion – and looks like everything’s up and running – thanks for sharing your experiences and publishing them – that’s what ham radio is about!

        I still have to perform the narrow-banding conversion – but the kit link you provided is no longer alive. Got a place that you can recommend – or the specific parts needed for the conversion? I’ll have it done while the repeater is in the shop getting it’s cans tuned.

        Zack

        • K7VE says:

          The parts list is right at the end of the article.

          Component Model
          CF-1 CFV 455G V
          XF-1 NDK 21F7.5C DN21
          R35 1.2K CHIP RESISTOR

  7. Would like to utilize a TKR820 that is being taken out of service thanks for the explanation.

  8. [...] that hams always seem to come up with. That’s when I discovered K7VE’s post on “Converting the Kenwood TKR-820 to use with D-STAR“. These desktop Kenwood repeaters could be had on the secondary market for under $500.00, and [...]

  9. W1MSG says:

    After reading this I decided to build one myself using a Raspberry Pi for the computer. I cant wait for all the parts to get here ! Thanks, Great write up !

  10. Craig says:

    Just cant seem to get mine working with a MoenComm card ?? Made sure the cable was set up correctly just cant get the NaTools RF Test to work ??

    • K7VE says:

      Visit gmsk_dv_node Forum on Yahoo! and describe your specific configuration and what you have done to test.

      A few checks to make:

      1. Rcv and Tx inversion
      2. If you are seeing key up, but not hearing anything its usually deviation.

      — John

      • W1MSG says:

        When we run NATools and do the RF Check we dont see anything at all. I’ll post it up on a couple of the forums. Not sure why I am not getting anything out. We had to adjust the RX pot on the modem to get the RX Light on the modem to light up but still nothing ???
        Thanks, I hope I can get this figured out.

        • W1MSG says:

          In your instructions you are using Pin 3 on the repeater but my pin breakout says that pin is used as external CTCSS tone encoder injection input and should not be used for anything else? Is there a difference in the TKR-820 accessory ports ??

  11. W1MSG says:

    Thanks John ! My saga continues, and it appears I have some computer issues. Has nothing to do with the repeater. Hopefully I will figure the computer end of it out today and get the GMSK modem set up properly. Thanks for the Great Article !

    • K7VE says:

      One other thing, make sure you have the ‘beta’ software from DUTCH*Star, 1.00F will have issues.

      • W1MSG says:

        It was an alignment issue with the repeater, I have a different one that a friend aligned and it works perfectly. Thanks for all the help and doing the hard work setting one up!

        73 Craig

  12. Steve KD2OM says:

    Great article, I am planning on converting out TKR-820. Does it have to be narrow banded to use on DStar?

    73
    Steve KD2OM

    • K7VE says:

      Steve,

      You do not need to narrowband. However, it improves selectivity on the receiver for better results. The D-STAR signal is only 6.25 Khz wide, so if you can find the parts or a kit, it’s not a big project.

      73 – John

      • Steve Sykes says:

        Thank you John. Yes it doesn’t look too difficult. I will try to find the parts, but will probably get the repeater running as a hotspot first.
        I also have an old crystal controlled Tekk 2 watt data radio we used for 9600 packet in the 90’s. I am also going to try making that into a home hotspot as well.
        73
        Steve

  13. KG9DW says:

    Can you tell me which software packages you run on a Linux box to make the repeater work with a dvrptr board? And does it then support all of the features of an icom repeater?

    I have a tkr820 up as an analog repeater. It is a solid little unit! I’m hoping to be able to acquire another one for a d-star repeater.

  14. K7VE says:

    The repeater controller software for the DVRPTR board can be found at:

    Documentation at https://groups.yahoo.com/neo/groups/pcrepeatercontroller/files/Documentation/
    Software at https://groups.yahoo.com/neo/groups/pcrepeatercontroller/files/Beta/

    The gateway software is at:

    Documentation at https://groups.yahoo.com/neo/groups/ircDDBGateway/files/Documentation/
    Software at https://groups.yahoo.com/neo/groups/ircDDBGateway/files/Beta/

    This will enable you to run a D-STAR gateway. It is a bit different than the Icom G2 software (which only works with the Icom controller), but you will be able to link to repeaters and reflectors with more features than the Icom G2 software.

    Read: http://k7ve.org/blog/2013/01/gateways-for-d-star/ and http://k7ve.org/blog/2013/02/icom-g2-gateway-ircddb-plugin-or-ircddbgateway/

    You will also find helpful advice at the pcrepeatercontroller and ircDDBGateway Yahoo! Forums.

    You can run the entire repeater and gateway on a computer as modest as a Raspberry Pi.

    For full functionality, you will need to register a club callsign for the repeater at http://regsrv.ircddb.net/index.htm for credentials to interconnect with the network.

    • KG9DW says:

      So the big difference then between the G2 software and ircDDBGateway is the fact that I won’t be able to callsign route unless the repeater where the destination user is on is running ircDDBGateway or the plug-in for G2?

      • K7VE says:

        Yes, this is essentially correct.

        One other item, if someone is using DVDongle/DVAP to link directly to your computer over DPLUS protocol, they may have to use software other than DVTool, or make some configuration change

  15. KG9DW says:

    Hey John –

    I posted this over on the yahoo group for the DVRPTR_V1, but I wanted to share it here too…

    It’s ALIVE! The KD9AKF homebrew D-Star repeater is on the air in Heyworth, IL!

    My DVRPTR from Bruce arrived on Saturday…the TKR-820 arrived from eBay today…and since I had already built the interface cable and loaded the software on my Raspberry Pi, the entire system was up in running in under 15 minutes. Yes, I did a lot of work ahead of time – loading the image on the Pi, configuring the software, registering the club callsign…but absolutely ZERO issues getting this up and running!

    Thanks Bruce for making the boards available. And a special thanks to you John, K7VE, for giving me the inspiration to do this project. It was great to be able to assemble this system and have a working repeater after spending less money that what some would spend on a mobile rig.

    The next step will be to get the internet connection up and running at our tower site, and then a few hours to move the system to its permanent home. We’ll have the system up about 250′ on the plains of Central Illinois.

    73
    KG9DW

  16. Dean says:

    While I wont be making any D-Star mods, I am curious how easy these repeaters are to convert to a 70cm repeater?

    • K7VE says:

      Yes, you need to program these synthesized repeaters to your frequency pair (takes special programmer, you may have to ask around to borrow one, they are quite hard to come by on the used market and command a good price on eBay).

      There are some minor tuning steps after it is on frequency.

  17. Zack says:

    John,

    I’m planning on doing the same thing – have a MoenComm GMSK board and just acquired an beautiful TK-820 – so off to do the conversion – I’ll report back. Thanks for publishing this information.

    A question, your 12v source is a requirement of your DVRPTR board (as I don’t believe the MoenComm board requires that – 5v from USB is enough)?? So the supplier is supplying the 12v out?

    Zack – N8ZAK

    • K7VE says:

      Zack – have fun building your repeater.

      I find that sourcing 12V to a node adapter provides more stability than trying to run off of USB power. This, of course, depends a bit on the current available on your USB source.

      I haven’t run a Moen Board, though I think Jim does a great job as a supplier and in supporting his customers. I would seek his advice on powering his board as he has many customers and can share with you best practices.

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