VHF / FM splitter

[arguzin]

I've just fitted a Lowrance VHF radio on my 16' Sleekcraft and connected it to the VHF fibreglass antenna on the boat. I also intend to install a marine FM stereo on board. Would you recommend a VHF splitter for the FM stereo aerial? Or would they damage/interfere with each other? Would it make sense in the first place, since the range of frequencies is different? Would a piece of ordinary cable attached to a metal rod of the boat suffice?

 

[UncleWillie]

Re: VHF / FM splitter

... Would a piece of ordinary cable attached to a metal rod of the boat suffice?

New radios commonly come with just a Simple Wire Antenna that you route inside the hull.
Cheap but effective.
The splitter work just as well, but costs more.

If the signal is too weak, A Dedicated Antenna may be the only solution.

 

[jhebert]

Re: VHF / FM splitter

Arguzin--Since you are in Malta, could you tell me what frequency the commercial FM broadcast stations use?

 

[joed]

Re: VHF / FM splitter

The concern I would have with a VHF transmitter and an FM radio sharing an antenna is how to prevent the output from the transmitter from damaging the input of the receiver with its transmit output power.

 

[stevecur]

Re: VHF / FM splitter

I used a splitter on my last boat. It worked fine for me But, most of the areas where I fish the radio signals are weak no matter what antenna you use.

 

[UncleWillie]

Re: VHF / FM splitter

The concern I would have with a VHF transmitter and an FM radio sharing an antenna is how to prevent the output from the transmitter from damaging the input of the receiver with its transmit output power.

They are more than just two cables soldered together.

Without getting heavy into the magic of the Splitter/Directional Coupler
Keeping the Transmit Power out of the Receiver is exactly what they do best.

The Transmit Power goes to the Antenna ONLY and the returning Receive Signal is split up to both radios.
There is an equivalent circuit inside the Radio/Transceiver to keep the Transmitter from smoking the front end of the Receiver.

 

[arguzin]

Re: VHF / FM splitter

Arguzin--Since you are in Malta, could you tell me what frequency the commercial FM broadcast stations use?

They range from 88.7 to 106.6mHz. The national channel is on 93.7mHz.

 

[jhebert]

Re: VHF / FM splitter

They range from 88.7 to 106.6mHz. The national channel is on 93.7mHz.

Thank you for the information on the FM Broadcast band in Malta. It appears to be the same allocation as in the USA.

Not being familiar with the regulations of Malta, do you happen to know what polarization is used for transmission of the FM commercial broadcast signals in your country? Here in the USA the FM Broadcast Band has historically used horizontally polarized antennas for transmission, but in the last few decades many FM Broadcast stations in the USA are now using elliptically polarized signals, contain some vertical and some horizontal polarization in a mix. If in Malta your stations are primarily using horizontal polarization, it would not make much sense to use a vertical antenna to receive them. Trying to receive signals with a cross-polarized antenna often reduces the signals by a factor of 100.

If you can let me know what is the standard polarization for FM Broadcast Band signals in Malta, I could make a recommendation for an antenna.

In general, I do not recommend trying to share the antenna for your VHF Marine Band radio with your commercial FM Broadcast receiver. I consider the VHF Marine Band radio to be part of the safety gear of the boat. I would not compromise the safety gear for the purpose of getting some radio entertainment.