Power for a mobile radio to use as a repeater on top of a building and other questions related to the same!

[WRZF693]

Hi Again folks.. 

Question for some of you technically oriented folks..

I can't hit any repeaters where I live. They are like 35 plus miles away and there are many woods and forests and factories and such in the way. So, I want to be able to talk to my buddy and try to extend the range for both of us. He has a really tall building downtown in my small town that I can use as he's given me permission to do so. 
I'm thinking I'd like to use a mobile 50 watt radio as a repeater. Do I need two of them? Does anyone make a mobile type radio that has a duplexer in it for such use? 
How hard would it be to setup two radios at 50 watts to use as a repeater? 
Is it possible to use a solar panel to power such radios ? 
Any help would be most appreciated. 
If you've done this, please let me know and tell me about how well it worked.. Even if not 50 watts and just a simple repeater. I'm also considering just using a much better antenna and two 5 watt radios in an ammo can or something with a tall antenna.. I just don't know how well it would work.. ? ? ? 

Thanks folks... Great forum! 
Be well and be safe. 
Tim

[SteveShannon]

Welcome to the site!

Technically it is possible to do this, but practically it isn’t a great solution.

It would require two radios, a controller, and a duplexer.  You would have to ensure the two radios are well shielded from each other.  Buying a purpose built 2nd hand repeater will almost certainly be less expensive.  Don’t go cheap on the duplexer either, or the transmission line or antenna.

Solar power could be used to keep a battery bank charged up.

But it is possible.

There are all in one repeaters that are only five watts or so from Retevis that include a duplexer.  If you have line of sight you might be able to use one of those.

[WRYZ926]

Going with advice read on the forum, I suggested to the club to invest in a Bridgecom repeater or better versus trying to run two KG100G's for our repeater. We already have Motorola repeaters setup for 70cm and I'm not sure what the 2m repeater is.

We lucked out and the tower is 900 foot tall. Plus there are some abandoned antennas as either 400 or 600 feet that will work great for GMRS. We tested the antennas and hard line and got  a SWR of 1.3 on GMRS frequencies.

We did a test yesterday using a MXT500 and MXT575. I am 21.5 miles from the repeater and the base of my Comet CA-712EFC is about 18-20 foot above the ground. We had no issues talking to each other on simplex and low power settings.

[kidphc]

You could use a repeater radio = $$$. Or 2 kg100g with repeater cable, less $$$. Or old commercial radios and configure them as a repeater less $$$ (like kenwoods).

You would need a duplexer. Price will depend on if you choose a cheap Chinese brick duplexer or something like a 5 cavity duplexer.

Plenty of youtube videos on different configurations.

Depending on topography and antenna height. The repeater may not make 35 miles straight line.

Most of the repeaters around me (d.c area) will generally have an 18 mile radius. These repeaters are usually minumum 100' with no obstructions using all commercial gear. From the repeater (like a quantar), antenna (lots of comwaves) to heliax feed line using cavity duplexers (for the isolation, and power handling).



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[tcp2525]

44 minutes ago, Sshannon said:

Welcome to the site!

Technically it is possible to do this, but practically it isn’t a great solution.

It would require two radios, a controller, and a duplexer.  You would have to ensure the two radios are well shielded from each other.  Buying a purpose built 2nd hand repeater will almost certainly be less expensive.  Don’t go cheap on the duplexer either, or the transmission line or antenna.

Solar power could be used to keep a battery bank charged up.

But it is possible.

There are all in one repeaters that are only five watts or so from Retevis that include a duplexer.  If you have line of sight you might be able to use one of those.

Good points. I'm finding the VX-4207 radios are well isolated and shielded. I bumped power up to 20w for testing and still getting good range without affecting recieve. This is with a Tram 1486 on the side of the tower at 30' above ground fed with 50" 1/2" Heliax. If I get my antenna situation optimized where I can some altitude then I will just buy a commercial made repeater.

[OffRoaderX]

Using two radios like the KG1000G is not a great solution. It is a good way to learn about how stuff works, but it is not good, long-term option especially if you want many farz - its also fairly expensive.

I would recommend getting a used commercial UHF repeater like a Vertex 7000 or something like the Retevis RT97 - both will perform better than two KG1000Gs and will cost less.

Unlike many of the other responses you will get, I have actually used all 3 of these setups - The Vertex works best with a max range of about 70 miles.. The Retevis RT97 gets about 40 miles and the KG1000G setup, even though it has more power than the other two struggled to get ~20 miles... There are many technical reasons why the two KG1000G setup does not work as well that I wont get into, but trust me, and others will confirm, its not a good solution.

The RT97 will be much easier to run on a battery and solar power than any of the others.  I have also done this, and the RT97 lasts far longer because it uses much less power.

[SteveShannon]

1 minute ago, tcp2525 said:

Good points. I'm finding the VX-4207 radios are well isolated and shielded. I bumped power up to 20w for testing and still getting good range without affecting recieve. This is with a Tram 1486 on the side of the tower at 30' above ground fed with 50" 1/2" Heliax. If I get my antenna situation optimized where I can some altitude then I will just buy a commercial made repeater.

Some of the better quality radios like vertex, Motorola, etc., are well shielded (based on posts from some of the experienced radio technicians here). 

[WRZF693]

3 hours ago, Sshannon said:

Thank you Steve.. I'll check out the radio you mentioned.. 
Regards kind sir~!
Tim

 

Welcome to the site!

Technically it is possible to do this, but practically it isn’t a great solution.

It would require two radios, a controller, and a duplexer.  You would have to ensure the two radios are well shielded from each other.  Buying a purpose built 2nd hand repeater will almost certainly be less expensive.  Don’t go cheap on the duplexer either, or the transmission line or antenna.

Solar power could be used to keep a battery bank charged up.

But it is possible.

There are all in one repeaters that are only five watts or so from Retevis that include a duplexer.  If you have line of sight you might be able to use one of those.

 

[WRZF693]

2 hours ago, OffRoaderX said:

Thank you Randy.. I of course want as many Farz as I can get..  I need to get if possible around 40 miles because I will be doing some shooting and camping in an area that is really out in the middle of no where, but it's hilly and has a straight line of site to the building I'd want to put the repeater on except a hospital is blocking it.. So, I have no idea how much this will matter.. 
Thanks again sir! 
Be well and safe Randy!

Tim

 

Using two radios like the KG1000G is not a great solution. It is a good way to learn about how stuff works, but it is not good, long-term option especially if you want many farz - its also fairly expensive.

I would recommend getting a used commercial UHF repeater like a Vertex 7000 or something like the Retevis RT97 - both will perform better than two KG1000Gs and will cost less.

Unlike many of the other responses you will get, I have actually used all 3 of these setups - The Vertex works best with a max range of about 70 miles.. The Retevis RT97 gets about 40 miles and the KG1000G setup, even though it has more power than the other two struggled to get ~20 miles... There are many technical reasons why the two KG1000G setup does not work as well that I wont get into, but trust me, and others will confirm, its not a good solution.

The RT97 will be much easier to run on a battery and solar power than any of the others.  I have also done this, and the RT97 lasts far longer because it uses much less power.

 

[AdmiralCochrane]

Height = farz.   In my opinion, 40 isn't very likely unless you can get up 300 400 ft. 

[WRWE456]

It may be helpful to know how far it is from your place to your buddies tall building? Is said building where he lives? If it is maybe he can just put up an antenna on the roof, that may be all you need. If not then a repeater may be the answer. Also is there power there that you can just plug into?

[Radioguy7268]

40 miles is quite a stretch for a 4 or 5 watt portable to reach back to the repeater in most real world situations. I'd question why you think you might need 50 watts in order to reach 40 miles out, but you're not worried about the other half of the path - the repeater's receive side. If you need lots of power to reach out, how's that 4 or 5 watt portable going to answer back?

If there's power in the building, it's probably 10 times easier to just use that. I don't think I've ever put a repeater cabinet outdoors on a building rooftop. Even if they didn't want to have us penetrate the roof, we could always find a way to wall mount the repeater inside & then sneak a coax cable out onto the roof. I have had to use non-penetrating sleds and find interesting ways to hide antennas so that the building architecture was not 'damaged' by the sight of an ugly exposed dipole. But solar power on top of a building that already had existing service? Nope.

[WRYS709]

On 11/6/2023 at 7:43 AM, WRZF693 said:

Hi Again folks.. 

Question for some of you technically oriented folks..

I can't hit any repeaters where I live. They are like 35 plus miles away and there are many woods and forests and factories and such in the way. So, I want to be able to talk to my buddy and try to extend the range for both of us...

If chatting with your buddy is your primary objective and you can be line of sight with that altitude, get a couple of 50 watt Wouxuns and high-gain Yagi antennas aimed at each other and chat Simplex on the High Power channels.

[nokones]

On 11/6/2023 at 9:50 AM, Sshannon said:

Some of the better quality radios like vertex, Motorola, etc., are well shielded (based on posts from some of the experienced radio technicians here). 

I'll confirm that two Wouxun are not a good solution based on my personal experience. What did I learn from that experience, do not go cheap if you want it to work and have others enjoy your efforts to support the GMRS hobby and be one of the Kool guys on the spectrum with a repeater.

[WRWE456]

The last 2 posts I think are talking about two different applications of the KG-1000G's. WRYS709 is talking simplex (radio to radio) while nokones is thinking of building a repeater with them. Correct me if I am wrong. 

[WRZF693]

Thanks everyone for the answers. I tried to add reactions to everyone, but the forum software said I'd used up all my reactions.. Strange.. Anyway, it's 4 miles to my buddies house, but we have some property out in the country we want to be able to talk to which is about 33 miles away from the building as the crow flies.. Hence the reason for wanting the repeater. I may do what someone on here said and just get a 50 watt mobile radio.. I think that might be a better answer.. I'm not even sure then I can reach that distance, but it will be fun trying! Thanks again.. I'm learning here slowly! 

[WRZF693]

On 11/7/2023 at 4:58 PM, WRWE456 said:

It may be helpful to know how far it is from your place to your buddies tall building? Is said building where he lives? If it is maybe he can just put up an antenna on the roof, that may be all you need. If not then a repeater may be the answer. Also is there power there that you can just plug into?

Hi.. From his building to my place is only 4 miles and the HT's do fine, but we have property that is about 33 miles away and on top of a pretty big hill for this area.. The property is.. Only one hill any taller in the area, so it should I would think reach with even just a good radio and tall antenna.. I can get to his downtown location easily with my 5 watt beufeng radio.. It's 4 miles away in an urban area or partially and partially wooded, and down a hwy with lot's of businesses. So, I'm thinking with a tall antenna and a repeater of any power I should be able to reach the remote property since it's on top of a hill for this area and pretty rural.. Not a lot in the way except tree's and open space.. That said it's up in the air and with an antenna there up high I would think it would be possible, but that's just an uneducated guess on my part.. 
Thanks for the reply. Really appreciated.. 
Tim

[WRWE456]

UHF radio wave are mostly line of sight. As long as nothing is in the way distance can be very far with the curvature of the earth being the limiting factor. Altitude is the best way to remove obstructions from the path. If you can get hand held radios on top of hills with nothing in between you may be able to talk 100 miles or more. Hook them up to mobile antennas in cars is even better. It's when things start getting in the way that more power helps to penetrate forest's and buildings etc. You want to keep the antennas in the clear as much as possible.

Radio require a fair amount of just you experimenting to learn what works for you in your situation.

Good luck and have fun.