Re: Too many VHF aerials?
Scott SV Tengah
Brent - Fantastic information! The distinction between an AIS antenna and a VHF antenna is subtle but important and something I didn't know.
One thing I will add is that I went for RG-8X. The reason is the minimum bend radius spec for each type of coax. The RG-58X we have from Amel is junk. Nothing more I can say about that.
I went for RG-8X because the minimum bend radius is 2.5inches / 63mm and by my rough eye calcs, that's the bend you have to make to exit the mast and enter the boat. There's no way around that I found. RG-8U has a bigger required radius and LM-400 has an even larger bend radius requirement. If you examine the routing through the base of the mast, there's almost no way you can achieve that. And my understanding is that signal attenuation shoots up dramatically when you violate the min bend radius, negating much of the benefit of low loss cable.
I also skipped the junction connector as the coax enters the boat and instead replaced the coax from antenna all the way to the VHF. I also went with proper soldered terminals. I figure if I ever need to remove the mast, I can cut and re-terminate the coax then. For now, I'll enjoy the reduced risk of signal attenuation from and additional connector.
Also, the Shakespeare 5215 that I purchased connects the rigging to bonding, which was only done by Amel on boats built after 2009. The connection was made through the PL259 connector "outer" which connects to the shielding foil, which then goes to the ICOM VHF case, which then is connected to the bonding system.This revealed a small negative leak (Mass- light) which I traced to the bow light wiring that had been causing surface rust on my rigging. That was a good find.
Caveat: I am no engineer and don't play one on TV.
2007 A54 #69