Dfishin Posted April 21, 2015 Share Posted April 21, 2015 Does anyone know if you can mount two VHF aerials close to each other like mounted side by side? Without them interfering with each other? If so what are the minimum clearences? Maybe the fella from road runner parts could tell me Dave Link to comment Share on other sites More sharing options...
NaClH2OK9 Posted April 21, 2015 Share Posted April 21, 2015 (edited) I believe you need to get space between them. I've seen both 19" and 2m quoted on different sites. . Vertical separation ( one antenna above the other with the lower inverted) is practiced on some sail boats I believe but not practical on smaller boats. Why do you want 2 antenna? You can get radios that monitor multiple channels. Edited April 21, 2015 by NaClH2OK9 Link to comment Share on other sites More sharing options...
batfishing Posted April 21, 2015 Share Posted April 21, 2015 I actually don't know the answer, but am happy to check with a couple of our Aerial suppliers. My advice would always be to seperate them as much as possible, preferably opposite sides of the boat. To back up what Steve said on the 500mm separation, I did search this one. http://www.jpole-antenna.com/2013/07/28/how-close-can-i-mount-two-vhfuhf-antennas/ Sent from my iPad using Tapatalk HD Link to comment Share on other sites More sharing options...
Dfishin Posted April 21, 2015 Author Share Posted April 21, 2015 I thought this would get asked. I already have an aerial on each side of the boat ( one each side of the cabin symetrical ). port side has 27 Mhz starboard has VHF. The reason I am adding a VHF to have 2 is a few reasons. Mainly because of the distances we are travelling out to sea ( well beyond the shelf out to 1000 - 2000 fathoms maybe more if needed ) a second VHF would be wise as one could fail, Also in the comps we fish if you lose radio contact with base you must retire and head straight back to port.. Also to monitor 2 channels. If your talking about dual watch this is not what im looking for as it will only monitor 16 and another chosen channel. I know I can run the second radio off an aerial splitter but I think If I am installing another VHF I would rather keep it on its own Aerial. If I run a splitter and have an aerial issue causing no transmission this will then disable both radio units. Dave Link to comment Share on other sites More sharing options...
NaClH2OK9 Posted April 21, 2015 Share Posted April 21, 2015 Fair call Dave. I'm sure Ian will get the definitive answer for you but worst case you could run with a splitter and install a second antenna for backup but leave it unplugged. I'm interested to see where this goes. Link to comment Share on other sites More sharing options...
Dfishin Posted April 21, 2015 Author Share Posted April 21, 2015 I just had I thought. Ian! Can I get a splitter that will run VHF and 27 MHz eg VHF aerial with a VHF / 27 Mhz splitter. If so I'll change the port side aerial to a VHF aerial and run 1 VHF off it and the 27 meg rarely will get used anyway. Link to comment Share on other sites More sharing options...
batfishing Posted April 21, 2015 Share Posted April 21, 2015 27 and VHF are different bands, different aerials. Personally I would put an aerial each side, and remount a 27Mhz where you can. The bigger issue you will find is when transmitting on one, is it will come through the other one strongly, you may want to be able to reach the off switch or volume quickly. There is also a triple watch, 3 channels available. Im in a meeting most of tomorrow, but will research further Sent from my iPad using Tapatalk HD Link to comment Share on other sites More sharing options...
Dfishin Posted April 21, 2015 Author Share Posted April 21, 2015 Yeh I looked up the splitter which I cant do. and yes I was just reading the radio booklet and noticed the triple watch function which is handy but I will still be Installing the second VHF If I mount the second VHF aerial on the same side as the 27 Mhz. With the 27Mhz swithched off will the two aerials then not interfere with each other? So Mostly I would have the 2 VHF swithed on out at sea ( aerials on opposite side of boat ). If I want to run the 27Mhz ( Only very minimal use when im on the water with a few friends that only have 27) I can swith off the VHF which is attached to the aerial on that same side and if I want leave the existing VHF on? Thanks Ian Dave Link to comment Share on other sites More sharing options...
batfishing Posted April 21, 2015 Share Posted April 21, 2015 Yeh I looked up the splitter which I cant do. and yes I was just reading the radio booklet and noticed the triple watch function which is handy but I will still be Installing the second VHF If I mount the second VHF aerial on the same side as the 27 Mhz. With the 27Mhz swithched off will the two aerials then not interfere with each other? So Mostly I would have the 2 VHF swithed on out at sea ( aerials on opposite side of boat ). If I want to run the 27Mhz ( Only very minimal use when im on the water with a few friends that only have 27) I can swith off the VHF which is attached to the aerial on that same side and if I want leave the existing VHF on? Thanks Ian Dave Yes, yes Basically the aerials will only be an issue when transmitting, so you could have the 27 and the VHF on. Separating the two VHF antennas will give you the cleanest operation. I think you can get a splitter / switch to run two vhfs thru one aerial. But..... That doesn't protect your redundancy if the aerial fails 2nd ly every post forum I have read in regards to splitters etc, everyone reports a drop in performance, which is the last thing you want with the distance off shore your operating I understand your reasoning for two radios, my next boat, when I upgrade from the sportscruiser to a flybridge it will be fitted with 2 radios. When we bought the Luhrs back down from Queensland two weeks ago, I through in a hand held radio purely as redundancy as the boat only had one VHF fitted Sent from my iPad using Tapatalk HD Link to comment Share on other sites More sharing options...
locodave Posted April 21, 2015 Share Posted April 21, 2015 (edited) If that is your concern, which is great to have a back up, why dont you just remove the 27 meg and have two vhf? Edited April 21, 2015 by locodave Link to comment Share on other sites More sharing options...
fragmeister Posted April 21, 2015 Share Posted April 21, 2015 I believe you need to get space between them. I've seen both 19" and 2m quoted on different sites. . Vertical separation ( one antenna above the other with the lower inverted) is practiced on some sail boats I believe but not practical on smaller boats. Why do you want 2 antenna? You can get radios that monitor multiple channels. If I recall correctly from my early radio trades apprenticeship (man that was a long time ago!) Marine radios operate around 160Mhz which gives than a wave length of a little under 2 meters. However, the minimal separation for the aerials in the same plane is one quarter wavelength of a little under 500mm. This probably accounts for the two different figures you have found. I have to say that my tutor for this subject was an antenna geek and it was such a complex subject... so much so that I can hardly believe a coat hanger antenna for the car radio antenna would work at all! Link to comment Share on other sites More sharing options...
Dfishin Posted April 22, 2015 Author Share Posted April 22, 2015 If that is your concern, which is great to have a back up, why dont you just remove the 27 meg and have two vhf? Would like to leave it. Some of my family and friends only have 27 MHz . Only really use it inshore and estuaries. Link to comment Share on other sites More sharing options...
NaClH2OK9 Posted April 22, 2015 Share Posted April 22, 2015 I've not heard of issues with vhf and 27 causing issues. Only multiple vhf being too close. Link to comment Share on other sites More sharing options...
Guest 4myson Posted April 28, 2015 Share Posted April 28, 2015 You'll only get interference if both radio are transmitting at the same time . Since your saying that you'll only 1 or another depending on wher your fishing ( inside or out ) you'll have no issues .... Link to comment Share on other sites More sharing options...
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