SignaLink Modification to Support Two Radios
How D from Western Colorado.
For the last 8 months I have been playing with digital modes and really enjoying this facet of the hobby. My main setup is an iCom IC-718 HF rig with the Tigertronics SignaLink USB sound card/interface device. The IC-718 had been my only HF rig since I was licensed in September of 2016. I have used it to make PSK31, JT-65 and FT-8 contacts so far. Then a few months back I bought a Yaesu FT-891. This is a much smaller HF rig that I use for all of my MOTA, SOTA and other remote activities. I thought it would be nice to get my FT-891 working with the SignaLink so I could run digital modes when away from the shack.
I bought the appropriate interface cable but then needed to change the jumpers inside the SignaLink. If you are not familiar with the SignaLink USB, there are two rows of 8 pins on the main board. You use the small red wires to jump across the pins so that it matches your specific radio model. The picture shown is the jumper settings for the IC-718. Upon checking the diagram for the FT-891, three of the jumpers would need to be moved. So I changed the jumpers and with a little fiddling of the settings in the WSJT-X software, I was able to make digital mode contacts on my FT-891.
So now you see the issue. If you want to use the SignaLink with more than one radio, you have to open the case and reset the jumper wires. After doing that once or twice, you realize you need a better way. I could buy another SignaLink box, which is an easy fix but I wanted to save that money for another project. I have started on a small portable Raspberry Pi/ Linux project that will run off of 12 volts, can do Digital Modes and can interface with the SignaLink. I will be posting an article on that project in the coming weeks. Digital Modes To Go.
After looking over the design of the SignaLink and the interior space, I figured I could get a switch in there. It does not have to be very big. Low voltage, low amperage and only 3 wires to switch. I ended up finding a bag of triple pole double throw (3PDT) switches on Amazon for $13.37. It is more than I need but it’s good to have some in the projects box.
I started out by printing the wiring diagrams for both radios from Tigertronics website. If you want to do this project, this is the first thing you should do before you buy anything. Your two radios might have different wiring needs. I needed to switch 3 wires but you might need to switch 4, 2 or maybe just one wire. This will determine the type of switch you need. According to the instructions that came with the patch cables, when you are using the USB version of the SignaLink, you do not need to wire for power (PWR). The unit gets is power from the USB connection. If you did wire in the Power jumper, it would pull power from the radio, if available via the pin out settings on your radio. I am not sure what would happen if you were pulling power form both directions. Probably nothing but I wonder if your radio could get any interference over that power connection? Just a thought.
Next thing was to make a wiring diagram. I laid out the jumper connection and the switch on a piece of paper, labeled the connections and then drew out how the connects needed to be made. Referring to the jumper wiring diagrams as the same time. I took a Sharpe marker and put an I and a Y on the end of the switch to remind me which side was which. Anything I could do to help me get it right the first time.
Next I had to find a spot in the SignaLink case where I could install the switch and still have clearance to slide the main board back in. I settled for a spot on the right hand side and slid the board in just to make sure. Using a spring loaded punch I made a nice dimple to give the drill bit a good starting point. I didn’t want it to wander around. If the hole was any closer to the top, the switch wouldn’t fit. You can use a regular punch to do the same but the spring loaded punch is super handy. You can get a cheap one from Harbor Freight if there is one in your area.
It looked like 15/64″ was the bit I needed but I started out with 1/8″ to give me a pilot hole and make sure it all went smoothly. Drill the 1/8″ pilot hole. Take your time and make sure you wear safety glasses. This is especially important as the small drill bits can snap off. I’d rather have a small cut on my face than a $3,700 bill from the emergency room for eye surgery! Once the pilot hole is done, chuck the bit for the final hole size. Take your time. The case is Aluminum and if you have a sharp bit, it will drill very easy and very fast.
Now that you have the hole, you need to check and make sure there are no burs on the inside or the outside. I found a few small ones on the inside. I used a small flat head screw driver to scrape them off. If it still feels rough, get a small file and clean it up. Now you need to clean out the box and MAKE SURE there is no metal pieces in that enclosure! I cannot tell you how important this is. If one of those flakes falls on the board, you will let the smoke out. You know how important it is to keep the smoke where it belongs! So double check that you have removed all the burs and there is nothing to break loose later. Then double and triple check that there is no loose flakes in the enclosure. If you blow it out, make sure you still have those safety glasses on.
A quick test fit of the switch and I am ready to start wiring. Another thing to note is to make sure you have wire that will fit into the pin holes on the main board. It is pretty thin wire and the board has push in connections. I had stranded wire that I lightly tinned on the ends so they would go in without bending. Check your wire before you start the project. You should also use a wire that is flexible. I cut my wires about 3 1/2″ long so that it would be easy for me to assemble the wiring and then install the switch in the case without the main board installed. I have fat fingers and it would be hard and frustrating to try and install the switch with the main board in the enclosure. This is why you want flexible wire. As you slide the board into the case, the wires need to move with you.
I put the switch on my diagram, started cutting the needed wires and stripped and tinned the ends before any assembly. Double check your work. I had soldered the wires on the switch and then started to push the wires into the main board when I realized I still had two more wires to cut. Not a big deal but the fewer times you have insert and remove the wires from the main board, the better.
I finally got everything soldered and the wires attached to the main board. Now is the time to break out the ohm meter. Using the wiring diagrams supplied by Tigertronics, start with one radio diagram, set the switch for that radio and then test the resistance across the appropriate connectors on the main board. My Icom says the SPK connection should go to pin 1. Go through the three connections for each radio and make sure you have continuity across the correct pins. Everything looked good. Time to install the switch, slide the main board back in and make some digital contacts.
This is where I realized how important it was to have flexible wire. I had the correct wire but even so, one of the wires popped out of the main board as I was sliding it back in. I reattached it, made sure everything was secure and that nothing would snag as I finished assemble.
In my case, the switch is down for IC-718 and up for FT-891. I will add some labels later on. With everything connected I made a few contacts using FT-8 on 20M with the iCom. Then I flipped the switch, connected to the FT-891 and made a few more FT-8 contacts. Everything is working and I am really happy with the results. Not a complicated or hard project by any means. Like any project though, it was very satisfying when I was done. Only cost me a few dollars in parts and I can now take it on the road with my FT-891.
If you decide to make the same changes for your setup, please consider that this may void any warranty you have on the SignaLink unit. It doesn’t make any physical changes to the main board, so it might not. You just never know.
I hope you got something out of this little project, whether that is to make these changes to your SignaLink or just some ideas for other projects in your shack.
73, JohnnyF, WJ0NF, 100WAAW ID: 1849