Shielded power feed to VHF radio?

[Nick F]

Bought my 1974 GB42 in June.

I have been tracing out the wiring and discovered that the VHF radio has a dedicated power feed coming from engine room in a shielded 2-conductor cable. This shielded cable is relatively new. It has an inline fuse in the ER (I dislike having inline fuses hidden all over the place).

Has anyone else seen this (dedicated shielded feed)? Any comments on its necessity? (I like things simple)

I have temporarily changed the VHF power feed to be together with the rest of the instruments, fed by a breaker in the main DC panel - to see if the radio functions the same or not.

Comments?
Nick

 

[C lectric]

Nothing wrong with it other than the inline fuse. Ideally the shield should be grounded to the boat - side so any collected energy from local radiation sources will be bled away and kept to minimal.

Maybe the PO had an interference problem or had suffered an interference problem from an unshielded VHF power cable. More common an older gas engined boats and alternators but who knows now..

Note the shield should be grounded ONLY at the source -. Do not connect the shield at the VHF or anywhere else or you may get some other problems.

 

[Nick F]

Thanks C-Letric.
The shield is indeed only connected at the source.
My desire is to do away with this dedicated (extra) cable (and its hidden fuse).

Nick

 

[psneeld]

After being a professional marine electronics installer (yep a long time ago, but have read of any changes that differ in best practices)....I know of no good reason to have a shielded wire all the way to the engine room as we never installed one.

Other than twisting the power wire pair to eliminate interference with magnetic compasses, I would wonder what was on the boat to cause enough interference to have shielded power wire.

One can argue that a separate, independently charged power source (read battery) placed in a nearby area to helm station electronics well AWAY from house banks and engine rooms as an emergency power source is a good idea. It used to be and I bet still is required by the USCG on commercial fishing vessels.

Shielded antenna wire and data cables, but shielded wire from the engine room to a single radio? Can't imagine why..... but I am eager to learn a reason for it.

 

[Nick F]

Can't imagine why..... but I am eager to learn a reason for it.

I, too !

 

[Bob Cofer]

Just a wild guess here but perhaps at one time there was a SSB radio on board causing interference and this was a misguided effort to eliminate it. People sometimes do crazy things chasing issues.