You could use male and female 50 ohm BNC connectors. Just make sure they are listed to work with the type of cable that your antenna cable is made from. Here is a connector that works for RG 142 coax cable https://www.amazon.com/Eightwood-10pcs-Female-Connector-LMR195/dp/B074167HK8/ref=mp_s_a_1_2_sspa?keywords=rg142+bnc&qid=1554261050&s=gateway&sr=8-2-spons&psc=1
You will also need a crimp tool like this https://www.amazon.com/rmsdeal77-Connector-Crimping-RG-174-Connectors/dp/B00LV5V17E/ref=mp_s_a_1_fkmrnull_2_sspa?
A little heat shrink tubing also helps to provide a strain relief and makes the connector look professional.
I'll try to get some pictures of my project up tomorrow, but I just finished removing the ribs from my wings and pulling fiberglass off the tanks that the builder applied. In my case, the builder did not sand the tanks and the top fiberglass pulled up easily but the fiberglass was adhered very well to the spars and bottoms of the tanks. Pulling the ribs off is fairly easy but plan on them not being usable and making a whole new set. The Hysol epoxy softens with a heat gun and I used a sharp chisel to remove the epoxy while being careful not to damage the spars. I am not able to see your photos right now but if you're worried about the insides of your tanks, there is a website where someone cut and removed the tops of the tanks and coated the insides with epoxy. They then re-fiberglassed the tank tops back on. I'll see if I can find a link to that site.
Here is the link to that site: https://www.google.com/url?sa=t&source=web&rct=j&url=https://www.nvav.nl/images/stories/kitfoxresealingtanks.pdf&ved=2ahUKEwjnt4OKsYjhAhVr04MKHVReCGMQFjAAegQIAhAB&usg=AOvVaw3pFOfH7IRFtn2CVNmzT0Y7
I found a source for 2.5" diameter 0.083" wall tubing and they would be happy to sell you 13' 6" lengths. Unfortunately, they charge $4,432 for an 8' length https://www.twmetals.com/catalog.html?cid=tube-aluminum&id=44887-8
I was thinking maybe they have the decimal in the wrong place, but all of their prices are that high. They cater to the aerospace industry, so maybe that's the going rate for their customers.
You guys made me curious what the markings on the spars mean. Some of the markings on my spars are not legible. I tried piecing as much of the writing together and here is what I came up with: ALCOA 6061-T6 WW-T-700/6 AMS-4082 ASTM-B210
The 6061-T6 is the alloy and temper WW-T-700/6, AMS-4082, and ASTM-B210 are standards that cover aluminum drawn seamless tubing
I agree with Jim that the extruded tubing would probably be fine, but the factory used drawn seamless tubing and the cost difference is not that significant. I wouldn't take the chance on the cheaper tubing.
I am also looking for tubing to extend my spars. From what I have found, the tubing is available as extruded or drawn. Both types are extruded, but the drawn is pulled through a die which increases the strength and makes the tubing more uniform and straight. I will be going with the drawn tubing for my extensions.
A guy in the EAA chapter I was in had a Viking 110 in a Sonex that he was building. He was really excited about the engine and was saying the Viking 130 has even more power with similar weight. As Ronin commented though, I think the disadvantage is weight. Isn't the 912 bare engine weight closer to 130 lbs?
The diagram shows the correct way to wire it. I was thinking you were intending to measure the return current through the fuselage to the battery, and that is why the ground wire was connected to the shunt. Whatever you do, make sure you protect that positive battery lead. Unfused wires make great arc welders.
Yep. There is no voltage drop across the shunt the way the it is wired. Your fuselage ground should go to the shunt terminal on the right and the battery negative should be connected to the shunt terminal on the left.
If you zoom in on the first picture, you can see the cable going through the top of the rib tail. It looks like the aluminum tube in the trailing part of the wing tip bent up and in. He might be able to bend the tube back down but if it bent in as well, there will be less tension on the wire and the whole wing trailing edge will be floppy. He will definitely need to check that before flying again.