Better coverage

emsbuff3240 · Post by **emsbuff3240** » Sun Sep 03, 2006 7:31 pm

Im looking for better coverage in the GMRS band iI have 3 portables MTS2000, CP125, TK360. I was looking into getting a base, however I read on a website that on the GMRS band antenna height is the biggest factor. Would it be better to adapt one of my portables to a roof antenna, or to buy a base and put it on a roof antenna. I would rather adapt the portable because it is more economical, but I was wondering what everyones thoughts were on this.

Rayjk110 · Post by **Rayjk110** » Sun Sep 03, 2006 7:50 pm

Well, if you use a mobile, you obviously get more power out, and have the convenience of still having a readily avaliable portable, whereas using a base with 1, you loose one to use. If $$ isn't a huge factor in this, I would recommend a CM300/GM300/MaxTrac at 25w should do, depending on how far you want to talk. LMR400 or higher coax should do.

HLA · Post by **HLA** » Sun Sep 03, 2006 11:48 pm

aren't those frequencies limited on power? but it would definately help you if you got your antennae outside of your vehicles and up as high as possible. you could apply for a license and get your own frequency for higher power or frequencies if you were to upgrade to a repeater.

emsbuff3240 · Post by **emsbuff3240** » Mon Sep 04, 2006 5:19 am

Jeff, I do not need mobile, in vehicle radios, just a base to portable and the "General" GMRS Frequencies are limited to 50watt power. I would eventually like to upgrade to a repeater but for now a base to portable operation is fine.

HLA · Post by **HLA** » Mon Sep 04, 2006 10:41 am

yes but you are only as strong as your weakest link, and that's the portable inside a vehicle and that's only going to be good for a couple blocks in the line of sight. but if you get that antennae outside the vehicle you will do alot better. what kind of range are you looking for?

WA3VJB · Post by **WA3VJB** » Mon Sep 04, 2006 12:48 pm

Jon, antenna height is your biggest factor in a simplex system where mobiles talk directly to a base station.

Do your best with antennas at both ends. You can get an experimental sense of range by taking a magnet mount UHF antenna, putting it dead center on the roof of your car, and connecting it to your portable inside the car.

At the base end, getting the antenna as high and in the clear is a good start, but you must feed it with the best coax you can find, preferably "heliax" if you're serious, or, Belden RG-213 or eqivalent if this is a trial.

What's nice about your efforts now is that they also guarantee you the best range into a repeater system when that day comes.

Paul/VJB

emsbuff3240 · Post by **emsbuff3240** » Mon Sep 04, 2006 1:29 pm

Thanks everyone, I am probably going try using one of my portables as a base downstairs and run the cable to the attic with a UHF antenna that would sit outside the window, any antenna suggestions.

motorola_otaku · Post by **motorola_otaku** » Thu Sep 07, 2006 8:27 am

emsbuff3240 wrote:any antenna suggestions.

Any fiberglass omnidirectional antenna will work. Just to pull a number out of a hat, look at the Maxrad MFB-4503. As far as using a portable as a base, well.. it works, but it's more of a hassle in the long run to keep having to connect and disconnect it from the outside antenna when you want to carry it around. Plus, you're putting strain on the antenna connector on the radio having a length of cable connected to it. Motorola Maxtrac mobiles in the 450-470 range are supercheap on Ebay these days ($30-70 range), so really there's no excuse not to put a dedicated radio in for your base station.

emsbuff3240 · Post by **emsbuff3240** » Sun Oct 22, 2006 5:05 pm

Just a follow up here...

I decided to set up the repeater since I had the cash, everything is at the radio shop right now getting set up/tuned

For an antenna I have a Tram from this ebay auction(works great):
http://cgi.ebay.com/ws/eBayISAPI.dll?Vi ... &rd=1&rd=1

My TX radio is an M1225 listed here:
http://cgi.ebay.com/ws/eBayISAPI.dll?Vi ... &rd=1&rd=1

My RX radio is an SM120 listed here:
http://cgi.ebay.com/ws/eBayISAPI.dll?Vi ... &rd=1&rd=1

This is the duplexer I got, although I bought it from a board member not this guy:
http://cgi.ebay.com/UHF-50W-6-CAVITY-DU ... dZViewItem

The antenna is mounted 10 feet above the top of the second story of my house. It has approcimately 60 feet of Belden RG-8 coax cable going to it. I would have gotten better but it was totally free and brand new. It gives me a very good coverage area. As soon as I can get adaptors for my portables to a mini UHF for the antenna on the top of the vehicles I think my coverage area will be increased even more. I am operating on GMRS( I have my license)

If anyone has one of these adaptors drop me a PM, I need one for a CP125 and an MTS2000(SMA).

I just have a cheap cable with no actual "controller" yet.

This all runs on a radio shack 15 amp power supply. When I get it all back I will post pics.

Thanks to Bayfire300 for all his help with this.

Also thanks for all your input.

Josh · Post by **Josh** » Sun Oct 22, 2006 6:28 pm

Keep in mind that those radios have tiny heat-sinks and using the repeater a lot will cause them to get hot in a hurry.

Also, 60' of RG8 cable is really bad you're losing a couple decibels right in the cable, similar sized LMR-400 cable loses less than 1/4 decibel in the line. I'd definitly recommend upgrading, you'll see a lot of improvement there alone.

-Josh

emsbuff3240 · Post by **emsbuff3240** » Sun Oct 22, 2006 6:34 pm

I will probably upgrade the cable and antenna eventually. But right now it works fine.

As far as the heat sinks go, this repeater is going to be used very very little, only for communicaion of my family. I am planning to build a custom bracket and attach a fan.

emsbuff3240 · Post by **emsbuff3240** » Mon Dec 18, 2006 1:49 pm

Here is my mobile setup:

lol, i doubt that that is a sufficent ground plane

these were taken with my cell phone, sorry for the bad quality.

And the base setup, since the pic was taken i put my cat5 block in and added the base mic.

sadly, the RG-8 will not fit out the window, i have to run it up into the attic and out by the sattelite dish.

Hopefully upgrading the Transmit radio to a maxtrac(with MDC features) or if i have the cash a CDM1250, and also, maybe the feedline.

Thanks all again for your help!