For all you VHF radio buffs...

waterinthefuel

Commander
Joined
Nov 15, 2003
Messages
2,728
I found out a cheap way to make a 3' antenna into an "on-demand" antenna of whatever length you choose. Simply go to a hardware store and purchase 3/4 inch male and female fittings, and 3/4 inch PVC cut to your length of choice between the mount and your antenna. Now, if you need greater range you can just hook up your "extension" and get your antenna as high as you want. When you don't need it that high, you can take it down and screw it back to the mount like normal, and just store the extension on the boat somewhere, for me it's in the strap-style rod holders.

I wanted to make my 3' the equivalent of an 8 foot, so I purchased one female, one male and one length of 5' PVC, total came to $4.53.

I am aware that it doesn't give you the gain of the true larger antenna, but it's cheaper and easier than fighting an 8' antenna constantly when you only need the additional range and reception occasionally.

Since you can cut the PVC (or in my case the hardware store sold it to me only in the length I needed) to any length you need, you can cut it to make sure it fits into the sidewell of the boat when retracted, or make sure it is long enough to clear something, if that is the case. The options are unlimited.

Hope this idea helps someone!
 

KaGee

Admiral
Joined
Aug 14, 2004
Messages
7,069
Re: For all you VHF radio buffs...

Don't know where you boat, but up here on the big lake, if there is an emergency I want my radio to get out. Thanks, but I'll stick to the known commodity.
 

ziggy

Admiral
Joined
Jun 30, 2004
Messages
7,473
Re: For all you VHF radio buffs...

i'm sure no pro on radios or antennas. but unless i ain't understanding proper. yer raiseing the height of the antenna on a piece of pvc. if that's the case. i don't think yer increaseing the leangth of your antenna. a 3' antenna is still only three feet and would perform as such. you are raiseing the hight of your antenna though. and since vhf is a straight shooting wave and goes off the cureviture of the earth. the higher it is the better range you should have....... from what i read. the antenna is the most improtant part of a vhf system. and for whatever antenna, the higher it's mounted the better.
 

Boatist

Rear Admiral
Joined
Apr 22, 2002
Messages
4,552
Re: For all you VHF radio buffs...

If you raise the antenna 5 feet really does not make that much difference.

If the 3 foot antenna mounted on a deck 2 feet above the water for a
total height of 5 feet your range would be 3.2 miles.

If you add an additional 5 foot to bring the total height of the antenna to
10 feet above the water you would increase the range to 4.5 miles.

However when do you really need your antenna to get out.
For me it if I hit another boat or a rock and am takeing on water,
Or in seas coming over the bow, Or an extream Medical emergency.

In each case I would want to get my position out and the number onboard quickly,
then try to plug the leak with something, fight the sea in a different heading,
or give emergency first aid or CPR to the victom.
Last thing I would want to be doing is trying to raise the antenna while the boat fills with water,
or the sea rolls the boat or victom dies from no first aid.

I want my antenna as high as practical so all I have to do is key the mike.
In Perfect storm they had no success in repairing the antenna to get a Mayday out.
 

arthat

Seaman
Joined
Oct 23, 2006
Messages
62
Re: For all you VHF radio buffs...

waterinthefuel,

I echo KaGee and Ziggy. In an emergency, time is of the essence there's no time to be Frigging with the Rigging! I do appreciate you being concerned with the costs we incur with boats though! Thanks for that.

Successful Boating,

Art
 

waterinthefuel

Commander
Joined
Nov 15, 2003
Messages
2,728
Re: For all you VHF radio buffs...

Oh, this isn't really for an emergency, this is only so I can talk to the base radio a couple more miles out, or over the top of a bunch of trees I just can't seem to penetrate with the little 3 footer down in the boat with me. It's 3 feet, but the mount is glued to the boat, about 6 inches from the bottom. Getting that thing up above me, out away from all the electrical noise of the electronics and above the engine has got to help.

My dad has much better reception with the identical antenna as me, mounted on top of his single story houseboat. He can pick up multiple NOAA stations and I can only pick up one, not all the time but most of the time.

As far as mucking with the rigging while underway, the original thread never said that. That's not what I was implying. If I know I'm going out I would set it up before I even left the dock, so I wouldn't have to do anything different when I got to my fishing hole; just lower the trolling motor and watch my graph! (I have a stick steer so I don't even have to get up! LOL)

It was only a suggestion. I said in the original thread it's not making a true 8 foot antenna, but height is more important than length with VHF.
 

ziggy

Admiral
Joined
Jun 30, 2004
Messages
7,473
Re: For all you VHF radio buffs...

but height is more important than length with VHF.

i'm not so sure this is wholey true. while height is very imprortant, so is leangth. this is what i understand

a 3' antenna is a 3db gain antenna. apperently half wave leagnth antenna. some of its radiated power goes up and is wasted. if you go up to a 8' antenna. it's a 6db gain antenna. radiated power is double the 3db andtenna, and the power is radiated flater with less wasted signal going up. while my figures may be incorrect. the longer the antenna. the better gain. the more power that can be radiated. also the higher the gain, the flater the signal being radiated. which is good for range. but if enough gain. can be bad as the signal is too flat. boats have a tendincy to rock. so the wave can be just shot off into space as the boat rocks. of course when ya roll back down ya get the great range untill the next swill.......i mean swell.....

i do think ya will see better range with a 3' antenna mounted higher though. you'd increase the range, by a little, by going higher. but the wave is still not as flat as the higher gain antenna and therefore will not achive the range of a longer antenna......

like i said i'm no pro so feel freely to straigten me out as i'm just tryin to learn about these vhf's myself....

have a great day folks. spring is coming..........i think......
 
Top