Antenna Location

[jpmurphy]

I am in the intitial stages of rebuilding a 1987 15' alum Gregor. I am planning to install a stereo, CB and a VHF Marine Radio. I'll be using the boat 99% for fishing and want to eliminate as many casting obstacles as possible.

My first thought is to mount all three antennas next to each other at one corner of the transom. Then I think about interference issues.

Should any of the antennas, or all of them, be placed a minimum distance from one another ? And, should I consider elect interference from the outboard while running ? And, after readin 90% of this forum; it would be best to use one common ground for all three antennas yes ?

 

[tashasdaddy]

Re: Antenna Location

using the correct spark plugs will eliminate motor interference, QL plug. stereo use one of those rubber antennas. your VHF and CB should be separated. i see not need for a CB in a boat.

 

[pvanv]

Re: Antenna Location

TD is right on the money. If you use resistor-type spark plugs, you won't suffer much ignition interference.

As for the antennas themselves interfering with each other, yes, to a degree, the VHF (around 150 MHz) and FM (about 100 MHz) will "talk" to each other somewhat. However... You can run a single VHF antenna, and for the cost of a decent marine FM antenna, get the Shakespeare 4357 splitter, which lets you connect the FM radio to the same antenna. It's basically a notch filter, so transmitting on the VHF won't spill into the FM receiver. We use one on our sailboat, with great results. The FM reception is much better than the short "rubber ducky" antennas. There used to be two different models of the splitter -- one for the short, sailboat antennas and a different one for the longer powerboat antennas. Shakespeare has recently come out with one unit that works for both applications. If you go for the splitter, and it's been on the shelf a while, be sure to get the correct unit.

The CB (about 27 MHz) won't "talk" too much to the VHF (except for harmonics, which any decent radio should be filtering out anyway), but should be separated -- say on the opposite corner of the boat. If the antennas are bare stainless whips, you will at a minimum want them far enough apart that they don't ever touch each other.

Who uses CB on boats these days?

 

[tashasdaddy]

Re: Antenna Location

yes i looked into the splitters, they get really expensive, that is why i went with the rubber am/fm antenna. http://www.iboats.com/Prospec_Am_fm...32627936--**********.225854234--view_id.39439

 

[Expidia]

Re: Antenna Location

I too went through the same decision as my rig is just short of 15 feet.
Originally I was planning on mounting it to the right of the console but then read it would be too close to the VHF on my size rig so I opted to mount it on the transom.

I trailer so I have to put it down anyway so I just drop it down when fishing or using my down rigger.

No need in my opinion too for a CB. Why not just use your cell phone to call a friend who is on the water too.

Before I bought the 8 foot VHF antenna for the stereo I first used an antenna that I found in an auto store for about $20. It's powered off the battery and works great (when there are stations close by). It's a strip that sticks along the underside of my dash. But I found on the waters where I go there are not that many stations due to all the mountains.

I also have an Ipod that plugs into the stereo and that was OK for a while but it's not a waterproof setup.

I also purchased that VHF/FM/AM splitter that others noted above when I ordered the 8 foot antenna, but never even opened the package (paid about $39 for it on the web) because I went with the ultimate way to go in my opinion, which was to mount a tiny puck antenna on the bow in front of my GPS antenna and simply transfer and plug in my Sirius radio from my car to the boat whenever I'm on the water. Once you go that route you won't want to leave the boat. For $13.95 I get crystal clear radio commercial free on most stations, news and entertainment channels from "any" body of water. There will be those that say "Why would anyone need a radio on a boat?" To each his own opinion. I love slow trolling at 1 mph for Lakers on an 80 degree sunny day while listenening to classical music tunes and a chilled bottle of Beer or Chardonay in the cooler! And sometimes a fish even takes my lure which breaks up my routine but I take a pic and toss him back quickly so I can get back to jus do'in nuth'in again.

The Sirius antenna is now right in front of the GPS antenna

Here is a pic of the Sirius suction cupped to the windshield

 

[jpmurphy]

Re: Antenna Location

Many thanks for these 3 replies. And, I suppose the thought of a CB is/was probably over kill. I'm just trying to cover all bases while still in the design stage. Hate to get everything all nailed down and then go opps, what about that other thingie I was thinkiing about.

I hate to back step. Too many years in uniform I suppose.

At this point I'm leaning towards an AM w/the rubber ant ontop of the console, just in front of the windshield and a VHF Marine w/8' ant mounted on one corner of the tansom. This seems to be the logical approach and I'll be sure to use the correct plugs as well.

Thanks guys. This site is a life saver.

 

[tashasdaddy]

Re: Antenna Location

if you do any trolling you may hate it. although, unless broadcasting, it will recieve in the down postion, not as well but a boat in trouble close enough for you to help, you will hear. i have a center console pontoon, am/fm one side of console, vhf other side.

 

[jpmurphy]

Re: Antenna Location

if you do any trolling you may hate it. although, unless broadcasting, it will recieve in the down postion, not as well but a boat in trouble close enough for you to help, you will hear. i have a center console pontoon, am/fm one side of console, vhf other side.

May hate what ? The transom mount ?