Built by WA1PB - Peter Busha
Overview:
The Kenwood TM - 281 digipeater build required a modification to the radio. This modification was to establish a 6 pin mini din cable to allow the radio to be used with digital modes.
I recently had been playing around with the Digipi software for the Raspberry Pi and have wanted to expand the APRS network here in VT. I already had most of the basic pieces for this build but spent some time researching how to use the Kenwood for this project. My research led me to this YouTube video which outlined the simple process for adding the cable to my radio.
Material List: (Clickable Affiliate Links)
- Kenwood TM-281 2 meter radio
- Raspberry Pi Zero 2w
- TOADS Digital Interface Board
- TOADS DB6 Daughter Board
- Digipi software for Pi
- Mini DIN 6 Pin Male to Bare Wire Adapter Cable
- USB to Micro USB Adapter
-
Uxcell 10 Pcs Black UF90B 9mm Dia Clip On EMI RFI Noise Ferrite Core Filter
Procedure:
Watch the YouTube video from above a few times….
Step 1: Drill hole in back of radio. I found a drill bit that was just about a perfect match for the cable that I purchased. I carefully drilled out a hole through the back of the case. Once the hole was drilled, I used a zip tie on the inside of the radio to prevent the cable from being pulled back through.
Step 2: If you buy the cable that I did, the pin out looks like this. You can consult the
literature by Temporarily Offline for their pin out of the daughter board if needed. I used four wires, brown, green, black, and red. (editors note: verify cable colors before soldering)
Step 3: Solder wires. Again, see the video for this. The red cable is ground and is soldered at the rear of the radio near the entrance cable.
The brown cable is soldered to the DTMF pad. To me, this was the most difficult task of the entire project because there is no solder there and the via is very small! Take caution here!!
The black and green cables get routed up into the face plate. There are two small clips located underneath that get pried out with a small flat head screwdriver. The video does a nice job explaining where these get soldered. Green is our PTT and black is audio in.
NOTE: in the picture below you will see a red and yellow wire going up into the faceplate. I initially made a mistake with how I was reading the pin out and discovered that I needed to be using the green and black wires.
Step 4:
Configure Digipi software. I am going to assume that the person reading this is familiar with how to do this and or can watch KM6LYW’s YouTube channel to get this done. The current version has a choice for the TOADS DI board!
Step 5: Tune radio to 144.3900 Mhz and start digipeating! Good luck.
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