DISCLAIMER: This is not an "official" NWDR project and any information is provided for your own edification and enjoyment. We will not be providing any support for what's here other than the author will answer questions in the associated forum as she feels willing and able. This is meant to be an example of what can be done, not a complete "how-to" guide to building your own.
This is a work in progress, and I will be adding to it as I finish up various pieces.
I have been working for a number of years on a combination repeater/digitpeater for doing digital protocols on a mountaintop here in Oregon. First stabs at this included gluing various D-STAR node adapters and the TNC-X to a Raspberry Pi and interfacing those to my Tait T-800 Series 1 repeater components. This required a *lot* of moving pieces and cramming a lot of electronics into the Tait chassis. I have always hoped, as a developer for NWDR, that I would one day be able to have everything I wanted on a single board. That day has now arrived with DRAWS™. The dual DIN6 inputs makes interfacing everything easy, and a single board solution doesn't take much space in the repeater chassis.
To be sure there are issues with trying to split the stereo CODEC into single mono channels for each of direwolf and MMDVM, but I'm in a good position to solve these issues and potentially contribute the solutions back to the community.
Since the hardware build is mostly complete, I'll post pictures here for people's consumption. As I proceed with the process, I'll post configuration files as examples for folks of what works for these applications.
This is the mostly empty repeater chassis waiting to be filled by creamy Ham Radio goodness:
The Pi and DRWAS will be mounted on a sheet metal plate that goes in the middle slot. The connectors will be pointed backwards for easier access to the connections.
I bought a few copper heat sinks just as a safety precaution as repeater sites aren't necessarily the most environmentally stable. I got them from Amazon: https://www.amazon.com/gp/product/B07H1718SQ/ref=oh_aui_detailpage_o05_s00?ie=UTF8&psc=1. You get three sets of heat sinks for $13, and I have plenty of Pis to use them on. The copper ones should conduct more heat and are lower profile so they don't interfere with the DRAWS™ board. These are mounted on a Raspberry Pi 3B+.
The Pi gets mounted on the sheet metal plate with the AdaFruit Standoffs and some 2.5mm screws on the bottom via holes drilled in the plate. The DRAWS™, of course, goes on the top.
It is a real pain that the ethernet connector is on what will be the top of this setup. This means that it will be difficult to plug and unplug as may be needed during setup and maintenance. I could use a right-angle cable to attach it, but that will require special cables that aren't necessarily readily available. Instead I found this adapter from Amazon that will turn the ethernet connector at a better angle.
The major part of the hardware project was running the wires from the various 15-pin D-SUB connectors on the back of the Tait repeater components to the various power and signal levels. I used a cut-in-half PS2 keyboard cable for both of the connectors into the DRAWS™ and installed terminal blocks to distribute power and ground. I plan on posting more detailed wiring diagrams here, but I have done some internal wiring on the receivers that I'd like to document for folks as well during that process. The end result looks like the following, though. There is the missing speaker panel up front as I'm trying to find some replacement 2" speakers to replace the damaged ones that were in there. You will see the Pi assembly in the center slot on edge. It's intentionally downplayed to placate repeater site operators who are computer-phobic. This way it appears to be part of the repeater itself.
I am currently in software development and testing. The main obstacle here is the splitting of the stereo channels into the mono components in ALSA so that I can run both the mmdvm software and dire wolf simultaneously. The mmdvm will be going to the right side of the repeater, which is 70cm gear. The left, which is 2m, will be going to the direwolf instance.
More updates here as I work through issues.