M1225 Repeater?

SOC · Post by **SOC** » Sat Jan 06, 2007 6:42 pm

Hello,
Im have a time with building myself a repeater.Can i take two M1225 Uhf mobiles and make them into a repeater? and do i need a duplexer? Or can i get by with two antennas?Please help!!

Thanks
Andy

emsbuff3240 · Post by **emsbuff3240** » Sat Jan 06, 2007 7:04 pm

Sure you can do this.

Unless you have approximately 40 feet of vertical seperation or, more isolation from the two antennas, you will experience RX desense making the repeater very inefficent, and your performance will degreade.

It is best to have a duplexer.

You also need a controller unit. This can be a R.I.C.K or just a simple cable, I have seen the 16 pin repeater cables on ebay for $10.

It is also a good idea to have good coax, LMR400 or Heliax if your really serious in order to minimize loss in the cable.

You probably also need atleast a 15 amp power supply for enought amps.

And of course a liscense to operate on the frequency.

If you have any questions you may contact me by PM for my aim screen name or phone number. I just finished setting up a GMRS repeater using one of these radios.

-Jon

HLA · Post by **HLA** » Sat Jan 06, 2007 7:08 pm

are these going to be uhf or vhf or what?

emsbuff3240 · Post by **emsbuff3240** » Sat Jan 06, 2007 7:13 pm

SOC wrote:Can i take two M1225 Uhf mobiles and make them into a repeater?

SOC · Post by **SOC** » Sat Jan 06, 2007 7:19 pm

The repeater is going to be UHF GMRS setup, i just got my license, i thought $85 was well worth it.As far as cable goes i purchased Superflex 3/8 Coax Hardline 10meters with type-N-males, but the same guy has LMR-400 listed as well, should i reconsider my purchase and go with the LMR? I have RS-20 Astron power supply, and as far as a duplexer what do i look for? ebay is my favorite......can i hopefully find one on there?
Thanks for the help guys.
Andy

Post by **HumHead** » Sat Jan 06, 2007 8:58 pm

I would definitely stick with the hard line. There has been a fair amount of discussion regarding problems with LMR, when used in duplex service, developing noise issues from the shields over time.

Some people think you can get away with LMR, some people are dead set again it. (Personally, I'll use LMR on a repeater for temporary duty, but not for permanent installs).

SOC · Post by **SOC** » Sun Jan 07, 2007 9:10 am

Here is a VHF/UHF duplexer i found on ebay, is this what im looking for?

Thanks

http://cgi.ebay.com/OPEK-VHF-UHF-DUPLEX ... dZViewItem

J.Sanor · Post by **J.Sanor** » Sun Jan 07, 2007 11:57 am

No, that will not do it. You will need something more like this

http://cgi.ebay.com/Celwave-UHF-6-Cavit ... dZViewItem

Doug · Post by **Doug** » Sun Jan 07, 2007 12:10 pm

SOC,
What you are looking at on ebay should actually be called a diplexer, here's a brief link with an explanation
http://en.wikipedia.org/wiki/Diplexer
A duplexer for repeater use is something completely different. Basically duplexers for repeaters are tunable cavities for isolation purposes and unfortunately not all duplexers are created equal.
I'm going give you another link and I'm going to warn you that before you start reading the information, make sure your comfortable and that you have some of your favorite beverage handy.

http://www.repeater-builder.com/rbtip/
Enjoy reading
Doug

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