I just bought a used TDL 450H, so i no longer have to rely on the internal radio in my R6-4. I had to order a cable for it and was surprised to see the fuse that came with it is 15 amps for powering it all from an external battery. My external battery cable for my R6-4 has a 3 amp fuse. Won't the base be powered by the 15 amp fused cable through the radio? If so i am wondering won't i be risking damage to the base if it' supposed to have a smaller fuse on it's power source? Should i be using a smaller fuse instead of the 15amp, if so what size do you recommend?
TDL450 will draw up to 15A peak inrush so normally needs that fuse.
Once settled down, at 35W TX it's drawing about 10A and down to about 2A at 2W TX.
It won't blow anything up, just means your base could frizzle a lot if something goes wrong as it may not blow the fuse.
If you are worried about it and TX at a lower power, you could go for a lower value fuse, or get a second fuse installed for the base cable. However, note it also has the battery still in there to feed into a fault anyway so you may not really be achieving that much.
We just paid for a rebuild on an r10 for this very reason. Keep the r6 and 450 on different cables or solder a second fuse holder after the 'Y'. Running your base with that fuse is asking for trouble.
Make sure to update your FCC radio license to go up to 35 watts now. Remember, even GNSS internal radios require a broadcast license from the FCC.