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.)
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 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 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.
| Signal | NQSMHS DE-9 Pin |
Molex 1625-15P Pin |
My Wire Color |
|---|---|---|---|
| Modulator In | 1 | 3 | White/Orange |
| COS/RUS | 2 | 13 | Orange |
| Discriminator Out | 3 | 4 | White/Green |
| PTT | 4 | 8 | Blue |
| Ground | 5 | 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.
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.
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:
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
Good luck with your conversion!
Well done on a easily understood, and step by step explanation, superb,
Regards
David G6OCD GB7HD Repeater Keeper UK.
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
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
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
As anyone modded a kendecom / MR4 Series repeater for Dstar I have several new ones with the cat 250 controler installed
Ernie G4LUE
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
Some TKR-820s will not move to ham frequencies. Research the repeater you are buying to make sure you can get it on frequency.
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
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
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
Wondering what is needed to narrow band the 820?
Dave N2KTO
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.
Would like to utilize a TKR820 that is being taken out of service thanks for the explanation.