Fixed VHF & Antenna, No Console

[jondavies]

I occasionally take my 15' Avon across to Catalina (25 miles each way) and though I think I'm pretty well covered for emergency communications (6 watt handheld VHF, SPOT, handheld EPIRB and a cell phone) I'm considering adding a fixed 25 watt VHF and antenna to provide greater range.

My boat is set up with for tiller steering so I will be mounting the VHF and antenna on a SS bracket on the transom.

I'm wondering if anyone with a similar arrangement has any tips or pics that I could draw upon for inspiration.

Cheers,

Jon

 

[0976claxton]

Re: Fixed VHF & Antenna, No Console

i'm bumping this one back up to the top. i'm curious about this as well.

 

[jondavies]

Re: Fixed VHF & Antenna, No Console

I should have closed the loop on this thread.

I went ahead and made a transom bracket from 1/8" stainless. I mounted the radio underneath and the antenna on top. The hard part was bending the stainless steel accurately but I know a guy with a machine shop and he did it for me on his press/brake.

I mounted the bracket using the existing U bolt that you can see just behind the radio, so I didn't have to drill any new holes in the transom.

One thing to note is that being so close to the motor, it picks up a little bit of static when the motor is running but I don't plan on using it when the boat is underway (the motor is so loud that it wouldn't be very practical anyway). It's really there as another safety/emergency option and but it's nice to know it's there if I need it.

 

[0976claxton]

Re: Fixed VHF & Antenna, No Console

Jon - Did you draw inspiration from a few sources before deciding on this? Just curious. I commend you on the safety factor. Especially if you are making long runs. I'm hoping to buddy boat to the Channel Islands in the future when the conditions are just right. Still, a good VHF would be handy for many other applications as well.

 

[jondavies]

Re: Fixed VHF & Antenna, No Console

I didn't really get any specific feedback - I just improvised (though I already had a smaller aluminum bracket on the other side of the transom for the fishfinder/GPS).

Let me know when you're planning a crossing to the Channel Islands -- I'd be interested in buddy boating if I'm available.

(Contact me via gmail -- 1jondavies)

 

[LippCJ7]

Re: Fixed VHF & Antenna, No Console

Uh guys, if I may add a word of wisdom, while its pretty apparent that you guys are having issues finding a suitable place to locate your equipment I would caution you that if your mounting the antenna to the helm I would not stand to close to the antenna. While the VHF frequency band does not get absorbed by the human body very well you could feel some effects from side spurs put off by the radio, Should you get a head ache or your eyes start to hurt something like that. It is important that you know that RF(the power output of the radio) is non ionizing radiation which means it does not change the molecular structure or body molecules it just excites them causing them to heat up and therefore the way to combat this is to stop transmitting and allow the body to naturally cool down which it does very effectively.

Not trying to scare you guys but staring down an antenna putting out 25 watts of power you should know the whole deal. From my experience I don't think you will feel anything but some are more sensitive then others to these effects and Marine VHF transmissions are usually short which will decrease the exposure the body takes.

I climb towers for a living where antennas can put out more then 1000 watts on much higher frequencies that are absorbed by the body, much more then VHF and I get heated up pretty regularly, its not a huge deal but food for thought.

In case you were wondering the reason why this is not a factor with hand held radios is because the FCC limits hand held radios to under 5 watts which is not enough power to hurt a fly. Cellular phones put out less then 1 watt.

 

[jondavies]

Re: Fixed VHF & Antenna, No Console

Thanks for the words of caution. That's definitely something to bear in mind.

I have a 6W handheld radio that will be more than sufficient for my communications needs 99% of the time (even then, I'm not exactly chatting up a storm -- I've only used the radio once since I got the boat, not counting radio checks).

The purpose of the fixed VHF radio is to provide another means of communications for those occasional times when I plan to go on extended trips and may be out of handheld range of the CG/Vessel Assist/other boaters.

I hope to never need it but the more communications options I have, the more comfortable I feel making those kinds of trips. More to the point, I can tell my wife I've taken all reasonable precautions

 

[waterinthefuel]

Re: Fixed VHF & Antenna, No Console

Uh guys, if I may add a word of wisdom, while its pretty apparent that you guys are having issues finding a suitable place to locate your equipment I would caution you that if your mounting the antenna to the helm I would not stand to close to the antenna. While the VHF frequency band does not get absorbed by the human body very well you could feel some effects from side spurs put off by the radio, Should you get a head ache or your eyes start to hurt something like that. It is important that you know that RF(the power output of the radio) is non ionizing radiation which means it does not change the molecular structure or body molecules it just excites them causing them to heat up and therefore the way to combat this is to stop transmitting and allow the body to naturally cool down which it does very effectively.

Not trying to scare you guys but staring down an antenna putting out 25 watts of power you should know the whole deal. From my experience I don't think you will feel anything but some are more sensitive then others to these effects and Marine VHF transmissions are usually short which will decrease the exposure the body takes.

I climb towers for a living where antennas can put out more then 1000 watts on much higher frequencies that are absorbed by the body, much more then VHF and I get heated up pretty regularly, its not a huge deal but food for thought.

In case you were wondering the reason why this is not a factor with hand held radios is because the FCC limits hand held radios to under 5 watts which is not enough power to hurt a fly. Cellular phones put out less then 1 watt.

As a HAM radio operator with permission to go 1000 watts at my house, I can say that you won't feel 25. Well, at least I don't know anybody that would. That would require you constantly transmitting at 25 watts, nobody does that. Most transmissions last less than 5 seconds. While the word of caution is certainly true, I think it's a bit much. 25 watts isn't enough to hurt a fly. My radio in my truck puts out 50 watts through an 18" antenna. It gets too hot to touch but you don't feel anything standing near it when it's transmitting.

 

[LippCJ7]

Re: Fixed VHF & Antenna, No Console

Well its up to you guys I just would hate for someone to get burned and then wonder what happened, up to you guys. Either guys be safe and have fun!!

 

[Chris-R]

Re: Fixed VHF & Antenna, No Console

Back in the "old days", guys would stand near radar antennas on ships to get warm but that's a long time ago and a lot of wattage. I had a girlfriend a long time ago whose father worked at Raytheon about 45 years ago. Raytheon "invented" the microwave oven accidently. A guy was holding a candy bar in his hand during a small microwave antenna experiment and the candy bar melted all over him. Viola! The microwave oven. Remember the Amana Radar Range? That was the first microwave oven and originally a Raytheon product. I don't know if Amana is around anymore.