AIS and VHF aerial swap

[OceanSprint]

I have an AIS aerial that says it can act as a VHF radio backup aerial.

I was thinking of terminating the AIS aerial and the mast top VHF aerial in the cabin with two panel mount BNC jacks. then terminate the coax from the AIS receiver, and the coax from the VHF set, with female BNC IN-line BNC connectors.

In this way i can connect either set to either aerial.

Any drawbacks?

Many thanks

 

[prv]

Either set to either aerial - are there any circumstances under which you're likely to want to connect the AIS to the normal VHF aerial? I can't really think of any, apart from testing perhaps.

Every joint in a VHF aerial cable will degrade its efficiency by some amount - hopefully not too much for BNCs with new well-made connections onto them, but still more than an unbroken piece of wire.

Given these two points, my preference would be for each aerial to connect directly to its intended equipment, but stow nearby an adaptor (either off the shelf or two plugs on a short length of wire) to connect the AIS aerial to the VHF set in case the main VHF aerial is ever lost.

Pete

 

[OceanSprint]

Yes, i think you may be right.

But could be in a busy shipping lane in the fog when my AIS aerial failed, or was ripped off by a low flying cetacean? Not very likely i admit.

Probably keep it simple is better.

 

[William_H]

The OP idea is OK however for most of us access to the back of the VHF is not so difficult so the cable can be unscrewed. If the AIS receiver is nearby hopefully the cables will reach to eb swapped. A better arrangement than additional connectors in a change over panel. If radios are not close enough then a piece of cable with PL 259 connectors plus a PL 259 barrel (male to male or is that female to female) would extend the antenna cable. Just keep it put away somewhere and even make up 2 cables if you want. This would be better than disturbing what is essentially OK as is. If you can't easily reach the back of the VHF and or AIS then the proposed arrangement might be best. good luck olewill

 

[prv]

If the AIS receiver is nearby hopefully the cables will reach to eb swapped [...] If radios are not close enough then a piece of cable with PL 259 connectors plus a PL 259 barrel

Not quite!

For some reason, AIS receivers customarily use a BNC connection for their aerials. So even if they're side by side, you need an adapter to be able to swap the aerials over, and the extension cable (if needed) would be better off with PL259 one end and BNC the other.

Pete

 

[OceanSprint]

Salty John had solution all along.

BNC to PL259 adaptor - permanently fitted to AIS receiver.

Then PL259 plugs on both aerials.

Simples.