Flip-flopping like a politician

So, I've decided it is the radar acting up again; not a small burr on the connector, not the batteries, but the Raymarine 2KW radome itself.

I may flop back again, but that's where I am at with it right now.

When we took the cat up earlier this week I took the opportunity to go out and take a more in-depth look at the problem. I had become convinced (erroneously, it turns out) that the radar had failed to work on our most recent sail due to low battery voltage... low voltage that should not have been there considering they've had several months on AC shorepower to soak up juice. This theory was formed when the unit failed to function while we were under sail (resulting in a "No Data" message on the radar display of our C80 chartplotter), but fired up immediately when we turned on the engine (consequently engaging the alternator to supply electricity), and was reinforced when I checked the voltage the next day and found it hovering around 10.5v... fully discharged in a 12v system.

Turns out that it was my multimeter that should have been "discharged" since when I took Graebel's much better device out, together with a specific gravity tester, they both showed the house bank at nearly full charge. Moreover, the radar wouldn't engage either off the house bank or when the engine was on and the alternator putting a full 14v into the system. Same "No Data" message (which isn't, incidentally, covered anywhere in the Raymarine documentation that I can find).

I checked all the connections on the low side of the system again. I verified that the C80 unit is putting out 12.5v through the radar cable connector, and I tested the impedance on the necessary data pair as shown in the Raymarine troubleshooting document, and it comes in at 113Ohms, lower than the 160 they specify. I think that is better, isn't it? But nothing I tried could get it running, and nothing I tested on the deck end showed any trouble.

Someone is going to have to go aloft and check the internal connectors at the radome. Hmm... I wonder who?

I'm a little nervous about it, actually; the only way to test the power at that end is to actually have the system powered up, which is usually not recommended. It is possible to have the system powered, but not in transmit mode, which will save the tester on any RF exposure, but if I recall correctly, the default startup state is "transmit." So, say it's not working, she accidentally wiggles whatever wire is causing the problem, and it fires up? I'll probably have to call Raymarine and see what they recommend.

Anyway, this is my number one problem at the moment. I am relieved that the batteries are in good shape, but no radar, going onto the rocky west coast, coming into the month known affectionately as "Fogust" by locals, is not a pleasant prospect. It need not be dangerous; we will simply have to sail in good weather and our options will be impeded by that requirement.

That said, the intermittent nature of the outages leaves me with some hope that this is simply the result of a loose connector somewhere, and hopefully it will be something easy for Mandy to spot once she gets up there and gets the lid off the radome.