Motorola maxtrac install help

[nwalker77]

Motorola maxtracs that operate on 151.820 MHz and 151.880 MHz. I have installed two on atvs and one in my truck ( for a base station) so we can keep track of the kids while they are out riding in the national forest in south west Missouri. Ive had a break down 4 miles from the trail head before, so we were worried about something happening to the kids and we wouldnt know about it or know what trail they were on. Anyway my current set up just isnt working but maybe a half a mile or so and im not rally sure what the problem is. Ive been told my first mistake was cutting the antenna cable down to about 2 foot long. Then ive been told that my other problem is a ground plane problem. They are installed in plastic dry boxes and the 18 inch 1/4 wave antenna installed on the top of the box. So im told that since there hardly any metal on the atv except for the frame, that is messing up the range on the radios. So like i said, any advice would be very appreciated. And i also need help finding a better antenna that isnt going to cost a fortune. Thanks!!!

 

[NeFire242]

You can buy antennas that do not require a ground plane. If looks are not important and you install it safely you could always consider a 5/8ths wave antenna which would give you 3dB more gain.

Something along these lines:
http://www.maxrad.com/product_overview_detail.cgi?id_num=10928

 

[stevelton]

The above poster makes a good point. Use a 1/2 wave antenna (which will be about double the length than your current antenna). 1/2 waves dont need to be electrically attached to ground planes, as it can use the earth as a ground. I would say that will be more of your problem than coax length. Some say that coax length will change the impedence enough, and that you have to cut it in odd numbers of 1/4 wavelengths, I would worry about it, Ive never had a problem.
One thing you could do is get a metal plate and attach the antenna to that. For VHF this would need to be as big as you can fit on the ATV, no less than 18x18 inches. Then you could use the 5/8 wave the other poster mention.

Here is an antenna that I think would work really well, for both the ATVs and your base.

http://www.alanmarcum.com/jpoles/jpole.html

These are friends of mine, and they will custom cut these antennas to your frequencies

Steven

 

[n8emr]

Motorola maxtracs that operate on 151.820 MHz and 151.880 MHz. I have installed two on atvs and one in my truck ( for a base station) so we can keep track of the kids while they are out riding in the national forest in south west Missouri. Ive had a break down 4 miles from the trail head before, so we were worried about something happening to the kids and we wouldnt know about it or know what trail they were on. Anyway my current set up just isnt working but maybe a half a mile or so and im not rally sure what the problem is. Ive been told my first mistake was cutting the antenna cable down to about 2 foot long. Then ive been told that my other problem is a ground plane problem. They are installed in plastic dry boxes and the 18 inch 1/4 wave antenna installed on the top of the box. So im told that since there hardly any metal on the atv except for the frame, that is messing up the range on the radios. So like i said, any advice would be very appreciated. And i also need help finding a better antenna that isnt going to cost a fortune. Thanks!!!

Unless you have turned the power down on the maxtracs, those frequency would not be legal on that radio. Both the licensed iternerate and license free MURS have power limits. Also I am not sure I want a 45watt mobile into an antenna a few inches from my body. RF exposure is going to be pretty high.

Now the antenna issue. I would build up a bracket and mount to the frame of the ATV then run the coax to the box. Also keep in mind with a legal power of 2-5 watts depending on service and a 1/4 antenna blocked by a human body dont expect a large range. Even worse if your in treed areas. You 1/2 mile may not be to far off the proper range. You can look at no ground plane antenna's but I dont think thats going to increase the range month.

 

[firetaz834]

Why not get you and your family members licensed for 2m (good family adventure, getting licensed), then you can get the maxtrac's programmed on a simplex 2m frequency and then you can use alot more power to communicate on.

 

[nwalker77]

How much would that cost for each person?

 

[kb0nly]

$14 testing fee, and a little to buy a study guide and have at it..

The Tech class ham radio license isn't that hard to get, but believe it or not i have seen some fail the test, it is possible despite what some say.. I'm a VE, volunteer examiner, if anyone is wondering how i have seen it happen.

 

[kb0nly]

Unless you have turned the power down on the maxtracs, those frequency would not be legal on that radio. Both the licensed iternerate and license free MURS have power limits. Also I am not sure I want a 45watt mobile into an antenna a few inches from my body. RF exposure is going to be pretty high.

Now the antenna issue. I would build up a bracket and mount to the frame of the ATV then run the coax to the box. Also keep in mind with a legal power of 2-5 watts depending on service and a 1/4 antenna blocked by a human body dont expect a large range. Even worse if your in treed areas. You 1/2 mile may not be to far off the proper range. You can look at no ground plane antenna's but I dont think thats going to increase the range month.

I was going to ask that question as well, proximity of the rider to the antenna, but you have to make due on such an install. I have seen plenty of motorcycle installs with the antenna on the top of the luggage compartment on the back, basically the antenna is right behind your head, so exposure is an issue.

I know, put tin foil inside your helmet.. LOL.. Just kidding, don't really try that.

 

[Josh]

What are you using on your base end? I have an antenna mounted at about 27', it's a 5/8 wave VHF antenna.

If you're getting a half-mile, you should be getting much more. Although I live in a suburban environment, I have no trouble receiving a portable radio running at 1 watt from a couple miles away, you shouldn't either, regardless of foliage.

Tell us about your base station end.

 

[ipfd320]

maxtrac issues

you also have to remember the grounding is the big issue...just like c.b or anyother radio if theres no ground to the antenna the output finals will heat up and eventually blow the radio along with high swr which will drastically reduce the radios output and range....by cutting down the antenna the swr definately increased...if u are using a hi powered radio i would suggest the bracket idea like posted and have it all tuned to the proper swr / freq range...good luck