Multiple VHF and Multiple PA Horns

[jwag956]

I have an ICOM at the helm, and an ICOM on the FB. Both have Fog/PA capability.
I have a PA horn facing forward and another one mounted aft.
Right now, each VHF is connected to a (different) PA horn.

Questions:
1) can one connect both horns to both radios with a simple splice?
2) is it best practice to have both horns active? (I presume so).

TIA

 

[Bmarler]

I have an ICOM at the helm, and an ICOM on the FB. Both have Fog/PA capability.
I have a PA horn facing forward and another one mounted aft.
Right now, each VHF is connected to a (different) PA horn.

Questions:
1) can one connect both horns to both radios with a simple splice?
2) is it best practice to have both horns active? (I presume so).

TIA

Pretty sure you’d need a switch to separate the radios. The output from one acting on the other might damage something. Those speakers are designed to be mics too, so no telling what might happen if you overload the mic input circuit.
The other issue is speaker impedance. Parallel speakers cuts impedance in half.

 

[ranger58sb]

2) is it best practice to have both horns active? (I presume so).

Not particularly, at least that I know of. One horn has been sufficient for us in fog...

-Chris

 

[MYTraveler]

I believe two PA's could share one horn, with in-line diodes to prevent the power of one unit backfeeding the other. But a switch is the more conventional approach (with a dummy load so that if transmission is attempted when the switch is in the other position, no harm will be done.

I faced this same question in commissioning my boat, which has 3 VHF units, each with a remote command mike, so there are 6 locations from which one can transmit: Pilot house, fly bridge, tower, cockpit and Portuguese bridge (port and starboard). For redundancy and simplicity, I chose separate horns for each. It admittedly looks a little crappy to have horns all over the place, but it is my belief that since my boat was built with a particular mission in mind (fishing anywhere from Panama to Alaska), form must follow function. In some systems, we implemented unnecessarily complicated solutions, which I now regret.