Emergency VHF antenna

[Guest]

My VHF radio is flush mounted. Can I fit a splitter in the main antenna co-ax so that, if the worst happens and I have to use the emergency antenna, I can plug it in without dismantling the boat, or should I move my radio so that I have access? Help please.

 

[Guest]

Trevor Dont fit a splitter, you will lose signal strength both on receive and transmit, you could fit a 50ohm coaxial switch in the existing coax cable. The switch will probably cost £15-20 you must make sure that it is ok for VHF use and suitable for transmitter switching, any local radio amateur shop should be able to help, above all make sure that the coaxial connectors are properly soldered. Remember if you are using the switch in an emergency it is another thing to deal with but certainly more convienient than swopping cables.

Good luck

 

[Guest]

Trevor Dont fit a splitter, you will lose signal strength both on receive and transmit, you could fit a 50ohm coaxial switch in the existing coax cable. The switch will probably cost £15-20 you must make sure that it is ok for VHF use and suitable for transmitter switching, any local radio amateur shop should be able to help, above all make sure that the correct coaxial connectors are used and are properly soldered. You will probably need to fit the switch in some kind of plastic box to prevent corrosion. Remember if you are using the switch in an emergency it is another thing to deal with but certainly more convienient than swopping cables.

Good luck

 

[Guest]

Re: Emergency VHF antenna and splitters

If you mean can you put in an additional, breakable, connection then this is the preferred possibility but you would have to be able to get at the cable run. Your question seemed to imply that you could not get at the rear of the radio nor the cable. You will need to get hold of some good quality 50 Ohm connectors to suit your coax.

If you mean can you put in a fixed power splitter in the antenna feed then this is another possibility.

BUT, in a properly designed 50 Ohm system you will lose 3dB, half power. Not only that but, if your normal radio is rated at 25W/1W you will have to have a splitter capable of these power levels. You would then have to have both antennas connected (probably not a good idea) or dummy loads.

 

[Guest]

On the whole I'd suggest an alternative of having a hand-held - far more likely that the VHF or coax/antenna will fail than you'll lose your mast (unless you're particularly kak-handed about rigging)

 

[Guest]

Does your Setup have a deck plug? If it does put a similer plug on your emergency antenna. The other way is to split the cable at a suitable place and put in a male-female BNC connector, with another similar connector on the emergency aerial. Maplin do the plugs, and many chandlers do to, but more expensively!

 

[Guest]

Best idea is to route a section of cable from the transmitter to a location where you can get at things and have the two antenna connections come to the same point. Then when the occasion arrises, just unfasten the connection from one and connect the the other.

 

[Guest]

Westmarine do a VHF switch from one TX to two aerials. I have one fitted on my boat, and with the use of an SWR meter, have found insignificant loss. One leg goes to the main aerial on top of the mast, and the other goes to a suction mounted emergency aerial that can be mounted on top of the cabin hatch in case of mast aerial failure or at the worst, mast failure. Look in the Westmarine catalogue under Antenna Switch.

regards, Philip