Need some clarity please

Good day all. I have recently acquired a 2004 380 Sundancer and it's equipped with all the original electronics. I have a couple issues and questions. First for the equipment. RL80C, RN300, Smartcraft, Autopilot. My first issue is the infamous "no fix" issue. I found a video on you tube that explained of the 3v battery inside the antenna could be dead. I tested the battery and it was dead so I replaced it with a new battery and within ten minutes I had a SD fix and everything seemed to be working. 30 minutes later and "no fix' again. So I retested the battery and it's good. Any ideas? My other question is does the rn300 receive gps and act as a repeater to the RL80C? I also wanted to know does the RN300 have its own internal antenna and if so cant I just use that? Any insight would be greatly appreciated

The rn300 should feed gps to the chart plotter via hsb cable. The antenna should be connected to the rn300 via the old school screw on connector. No internal antenna back then. What says no fix the rn300 or the Rlc80?

The original factory install of those items was to use a passive gps antenna (no smarts, no battery) connected to the RN300. The RN300 then took that raw satellite data and processed it into gps data. It then passed that onto the RL80c using Raymarine's Seatalk bus. But in 16 years previous owners could have changed some things. If you have a battery in your antenna then it's most likely a Raystar 125 "smart" antenna which processes the received data and passes it as ready to go gps data to the RL80c. Usually when someone did this they just stopped using the RN300 (some, like me, just took it off the boat and donated it), or they set the RN300 into repeater mode.

I have had something similar and making sure all connections were solidly made solved my issues.