Setting up a Repeater

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hfd921
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Setting up a Repeater

Post by hfd921 »

Looking for some input on setting up a repeater.

I guess first I should explain what I’m trying to accomplish, which would be to utilize portable radios flawlessly with in a 4-5 mile radius of the tower site(Believe me I know that’s asking a lot). Often at times the users will be briefly mobile on the go, in vehicles most likely restricting their signal strength but still need to be able to communicate. The area covered is fairly flat but does have a decent amount of vegetation and buildings, nothing over three stories.

I have the following equipment already and ready to install and put in operation.

*REPEATER:Gr300 repeater( turning down to 25 watts)

*ANTENNA: Tram/Browning 6155 UHF Antenna(Was with in the budget)

*COAX: 100 feet of LMR240 ultraflex

*TOWER: Is approximately 90 Feet tall

I’m just looking for some input and tips, everyone here on Batboards always has some great input and pointers on Dos and Do not's. Thank you

Some questions
*How high should I mount the antenna on the tower,with out creating to much loss ect?

*Is the LMR240 okay for this application?(It is what we have)
Jim202
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Re: Setting up a Repeater

Post by Jim202 »

If I can Make some suggestions without it being taken the wrong way.

1. You haven't mentioned for what service is the repeater to be used for? This goes to how you need to coordinate the frequency with and license it.

2. Once the frequency is nailed down, the duplexer will need to be tuned to that pair of frequencies.

3. Before you or anyone else jumps my case for bring it up again, I suggest that you do a search on LMR cable being used in repeater service. I'll just leave it at that.

4. The antenna is almost as important as tuning the duplexer. You sort of gave a rough presentation of what it was around you. If you have 3 story buildings and your antenna is mounted at 90 feet, there might be some shielding behind the buildings further out. The higher your antenna is, the better the coverage will be. The higher the antenna gain, the lower on the horizon your signal will be placed further out.

5. If you planning on using portables only, don't expect a whole lot of coverage with the height of your antenna.

6. Make sure you weatherproof the coax connectors well. There is all sorts of people that will be telling you how it should be done. In the cellular field, we used to put down two layers of a good electr5ical tape like Scotch 33. Then we would put down 2 layers of self fusing tape that overlapped the electrical tape. Then another minimum 2 more layers of electrical tape. Do not pull on the tape to tear it off. Use a knife so it won't migrate with time and come loose.

7. Last thing I will say is heliax type coax is the choice of cable to use on a repeater. Again I would suggest that you do a search for what others suggest for a feedline on a repeater.

Good luck on your efforts. It would help if you could find a radio savvy tech to work with you on the project. That person can act as a mentor and point you in the correct direction and save you time not making all the rookie mistakes.

Jim
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Bill_G
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Re: Setting up a Repeater

Post by Bill_G »

Image

LMR-240 is not the cable I would use either, but it may play in your favor with 6db of loss through 100ft into the standard reject only duplexer at a busy site. Not the most spectacular coverage, but usable around town. I put the antenna at 75ft with 3db gain. Hope this helps.
hfd921
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Re: Setting up a Repeater

Post by hfd921 »

Great stuff so far guys, Thank you

I apologize, I did forget to add but this will be used on commercial frequencies, all are properly licensed. The repeater is programmed and duplexer has been tuned.

I did do a search on here and else where I didn't locate much or missed it. I bought the 100 foot section of LMR240 RGX8 'N' Male Solder/Clamp Type Connectors 3M Brand Heat Shrink from the antennafarm, under the assumption that is what would work best. It was about a $100(no returns).
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Bill_G
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Re: Setting up a Repeater

Post by Bill_G »

It's all about losses, noise, and longevity.

Losses - With 6db of loss, you quartered your system power. 25W in becomes 6W to the antenna, with a similar loss on the inbound side - your 4W portables now have the range of 1W portables.

Noise - LMR is a braided shield cable that will eventually get noisy as the cable flexes. It takes years, but it will happen.

Longevity - Unless you bought the outdoor rated cable, the sheath will deteriorate in the sun, become brittle, and break off eventually. Again, it takes years.

LMR-240 is good low loss cable for indoor jumpers, mobile applications, temporary installations, or where cost is the driving factor and the losses are acceptable. Without knowing about this tower, the losses may be beneficial to you. There may be other UHF users on the site that could easily pass through the standard duplexer that comes with the GR series repeaters. A lossy cable helps cut down their potential interference.
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d119
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Re: Setting up a Repeater

Post by d119 »

As William has clearly stated, LMR series coax is not a good first choice for duplex environments due to the metallurgy of it.
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tsunami_australia
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Re: Setting up a Repeater

Post by tsunami_australia »

I'm using HFSC12D here for my VHF and UHF base antennas @33m a run (around 108ft apparently) and it has been SPECTACULAR. I upgraded from half that of RG213 and despite being double the length the improvement was indescribable, much more than I imagined.

On that, how does HFSC12D compare for loss? I got mine at a fire sale and never really found much paperwork in my searching of it's loss and actual real RRP price.
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Bill_G
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Re: Setting up a Repeater

Post by Bill_G »

tsunami_australia wrote:I'm using HFSC12D here for my VHF and UHF base antennas @33m a run (around 108ft apparently) and it has been SPECTACULAR. I upgraded from half that of RG213 and despite being double the length the improvement was indescribable, much more than I imagined.

On that, how does HFSC12D compare for loss? I got mine at a fire sale and never really found much paperwork in my searching of it's loss and actual real RRP price.
HFSC12D spec sheet

That would be a big improvement over RG213. About a third of the losses, and much quieter.
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Bigred
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Re: Setting up a Repeater

Post by Bigred »

And somebody better tell him to chuck the repeater and acquire one that's legal.
Lots and lots of watts...
Jim202
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Re: Setting up a Repeater

Post by Jim202 »

Bigred wrote:And somebody better tell him to chuck the repeater and acquire one that's legal.


He didn't say where he is located, so that question hasn't been addressed yet.

Not sure if wide band is legal or if he needs to be operating under narrow band rules. Depends on what country he is in.

Jim
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Bill_G
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Re: Setting up a Repeater

Post by Bill_G »

Jim202 wrote:
Bigred wrote:And somebody better tell him to chuck the repeater and acquire one that's legal.


He didn't say where he is located, so that question hasn't been addressed yet.

Not sure if wide band is legal or if he needs to be operating under narrow band rules. Depends on what country he is in.

Jim
See map above. Dem rulz aeply, ya hear?
Satelite
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Re: Setting up a Repeater

Post by Satelite »

Hello:
Am I missing something ?
A GR300 uses as one example the GM300 mobiles as rx and tx and the GR300 was made in narrow band also.
So wouldn't he be legal on commercial narrow band freqs using the GM300 narrow band mobiles to do a repeater setup in a GR300 ?
One of the GM300 narrow band mobiles model number as an example is M44GMC09C3A which is 438 to 470 MHz 12.5 narrow band at 25 to 40 watts (16ch) or say the GM300 narrow band model number M44GMC00C3A which is the 8ch version.
Satelite
hfd921
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Re: Setting up a Repeater

Post by hfd921 »

Loving the input on the coax. Thank you.

I'm not sure what Bigred is talking about, It's 100% legal, did I miss something. This GR300 unit is 12.5 narrowband, was planning on upgrading to a pair of CDM750s if all go well to replace the GM300s but no need to right now since everything is legit.
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escomm
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Re: Setting up a Repeater

Post by escomm »

Bill_G wrote:Image

LMR-240 is not the cable I would use either, but it may play in your favor with 6db of loss through 100ft into the standard reject only duplexer at a busy site. Not the most spectacular coverage, but usable around town. I put the antenna at 75ft with 3db gain. Hope this helps.
Your attachment is borked
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Bill_G
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Re: Setting up a Repeater

Post by Bill_G »

Yeah. This site doesn't autofit images. I had my choice of thumbnail or humongous. Chose the latter.
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Bigred
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Re: Setting up a Repeater

Post by Bigred »

The OP mentioned turning down the power to 25 watts. The only narrow UHF GM300s I've ever had my hands on were M04's set at 2 watts for LPI service. High power units are much rarer. If they are indeed factory narrow radios, then I capitulate.
Lots and lots of watts...
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escomm
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Re: Setting up a Repeater

Post by escomm »

Bill_G wrote:Yeah. This site doesn't autofit images. I had my choice of thumbnail or humongous. Chose the latter.
It's not even showing up. Just the word image. Likely you have it cached on your computer so it seems OK. The rest of us can't see it.
tvsjr
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Re: Setting up a Repeater

Post by tvsjr »

escomm wrote:
Bill_G wrote:Yeah. This site doesn't autofit images. I had my choice of thumbnail or humongous. Chose the latter.
It's not even showing up. Just the word image. Likely you have it cached on your computer so it seems OK. The rest of us can't see it.
Not quite. He cross-linked it from Communications.Support... if you're set up to auto-login over there (and not running in private/incognito mode) it works fine. Otherwise, their server returns an HTML page with "Invalid Attachment", which your browser doesn't know what to do with (since it's expecting a JPG/BMP/GIF/etc.)

Bill - it's generally bad practice to link images from other forums. At best, you get issues like this. At worst, the admin of the other site swaps the image out for some Tubgirl, 2G1C, etc. (if you don't know what these are, I would *not* suggest googling them...)
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Bill_G
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Re: Setting up a Repeater

Post by Bill_G »

escomm wrote:
Bill_G wrote:Yeah. This site doesn't autofit images. I had my choice of thumbnail or humongous. Chose the latter.
It's not even showing up. Just the word image. Likely you have it cached on your computer so it seems OK. The rest of us can't see it.
That explains Jim's comment. Ok. Thanks.
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