Repeater Antenna Selection

[WRZM243]

I am preparing to activate a Motorola GR1225 repeater in my area and would like input on an antenna recommendation.  The antenna will be placed on the end peak of a two-story home approximately 35 feet in height.  This is a small residental area in a rural community with a lot of farm land.  It is in the Willamette Valley centered between our coastal and cascade range.  Generally speaking, this small town has what I could consider a "normal" amount of trees you would generally associate with a residental area.  Other than that... the land is relatively flat between the start of our coast range on the west side and start of the cascade range to the east which is approximately 30 miles wide.  Thanks, Steve

[Sshannon]

6 minutes ago, tcp2525 said:

I watched the video and yes, I agree with you. But.... If someone is using SO-239s at 460 Mhz they're really not too concerned about a fraction of a db loss. What did he say, 3db loss through 10 connectors? So, using two in your system is going to be minimal. I have loads of old silver plated Amphenol connectors and happy with them because they are just good connectors. Everything I do on UHF goes through an N-connector if I can help it. I know hooking up the spectrum analyzer to measure return loss on a duplexer I can see the loss change as I tighten the N connector until it's fully seated.. That said, the ones DXE is selling are nickel plated brass and probably aren't that much better than Mr. Chung's nickle plated brass ones. I'm not knocking Amphenol's US made connectors, but you can easily reach the point of diminishing returns for hobby radio. If I were budget limited, I would rather invest in good feedline and use a marginal connector. The most loss is in long lengths of cheap coax.

He has a video comparing N connectors to UHF connectors too...  The differences were less stark than in these angle connectors, but he wasn’t testing at UHF frequencies. I prefer N connectors.  They’re just better connectors and more resistant to moisture penetration.

[OffRoaderX]

I use a Tram 1486 on my repeater.. Its not very expensive, it has a very low wind-profile and it does not look like some kind of space-antenna on the roof.

EDIT: .. and it is very easy to tune for GMRS.

 

Edited December 8, 2023 by OffRoaderX
added the tuning part

[BoxCar]

You aren't going to cover a large area with an antenna that's that high off the ground. The Tram is a decent choice, but the antenna needs to be tuned to the frequencies your repeater will be using for best results.

[tweiss3]

I used a Comet GP-6NC at a similar height. It worked decently, however, it snapped in half in a high wind storm.

[gortex2]

I use the DB404 and 408 but those are a bit big for your application. The TRAM is the economical way to get it up but requires tuning and care on installation. I like the Laird FG Series of antennas for applications like yours. The FG4605 is a solid LMR antenna and you only connect the cable and install. No tuning and no radials to worry about. I used the FG4603 and FG4600 on my Motorohome for years. 

https://www.digikey.com/en/products/detail/te-connectivity-laird/FG4605/3519995

 

[Flameout]

I have both a Comet 712 EFC and a Commscope DB404 and my repeater is a Motorola GR500 (I also have a few GR1225's) I don't understand why, but the Comet is performing better but either of those would be a good choice. Both so far have held up to some good winds. Some gusts over 50mph

 

[WRZM228]

Looking good. How many feet total. BTW I use to be in my moms roof and so as friends over 100 times. My new house, I don't think I can do it anymore. Signs of times. I'll probably end up renting a man lift.

 

[gortex2]

Feedline is another important consideration. If your going to be under 50' good LMR400 with the proper connectors will work well for your application. You want cable to be minimum length needed to get to the antenna and surge arrestor and not use adapters. 

[tcp2525]

23 hours ago, OffRoaderX said:

I use a Tram 1486 on my repeater.. Its not very expensive, it has a very low wind-profile and it does not look like some kind of space-antenna on the roof.

EDIT: .. and it is very easy to tune for GMRS.

 

Using the 1486 as well mounted to the side of the tower at the 30' level fed with 50' of 1/2" Heliax. I'm getting 5-7 miles usable range, which is good for the terrain I'm on. This covers all my fishing spots on the river using the HT. I would really like more range, but that's not going to happen until I get a better antenna and more height. So, no real complaints as I have realistic expectations for what I'm using.

[Flameout]

14 hours ago, WRZM228 said:

Looking good. How many feet total. BTW I use to be in my moms roof and so as friends over 100 times. My new house, I don't think I can do it anymore. Signs of times. I'll probably end up renting a man lift.

 

I have 50' of Wireman CQ1000 running to the Comet 712EFC and for the DB404, I have 25' of Andrew Heliax Ldf4-50a coupled with about 12' of Andrew Heliax fsj4-50b 

I'm still experimenting to see what works best, but with the limited gmrs activity in my area, it's tough to get feedback. 

[WRZM228]

8 hours ago, Flameout said:

I have 50' of Wireman CQ1000 running to the Comet 712EFC and for the DB404, I have 25' of Andrew Heliax Ldf4-50a coupled with about 12' of Andrew Heliax fsj4-50b 

I'm still experimenting to see what works best, but with the limited gmrs activity in my area, it's tough to get feedback. 

I wanna get the similar LMR-400 especially the solid core. I end up getting the LMR-240 for my initial setup because I know I will be going back and forth making adjustments. So as soon as I ironed the whole setup and I'm happy, that will be the time I will guy the best cable I can reach. But honestly I should be okay in this category or the highest RG8 since my setup is not even 50 foot cable. My antenna will be sitting right on top of our bonus room. The other nit pick the j-poles female connector is not really as rigid. It will be a big fight to muscle an LMR-400 and connecting it with minimal stress. Right there on just my test connection with the J-pole antenna sitting on my window pane. I can easily hit the repeater from my house really clear. Cant wait to get antenna mast and put it up soon.  When I adjust my radio to full power, I get exactly 50 watts but that's only 4 feet of RG-8 mini from my old SWR meter. I can hear the power supply really working as I key up after 3 minutes even its a 30 amp.

  

[Sshannon]

9 minutes ago, WRZM228 said:

I wanna get the similar LMR-400 especially the solid core. I end up getting the LMR-240 for my initial setup because I know I will be going back and forth making adjustments. So as soon as I ironed the whole setup and I'm happy, that will be the time I will guy the best cable I can reach. But honestly I should be okay in this category or the highest RG8 since my setup is not even 50 foot cable. My antenna will be sitting right on top of our bonus room. The other nit pick the j-poles female connector is not really as rigid. It will be a big fight to muscle an LMR-400 and connecting it with minimal stress.

  

Use an angle connector to take the stress off but be sure it’s a high quality one like this Amphenol. Don’t be lured into buying a cheap nickel plated one. This is the good stuff:

https://www.dxengineering.com/parts/aml-83-1ap-2

[WRZM228]

22 minutes ago, Sshannon said:

Use an angle connector to take the stress off but be sure it’s a high quality one like this Amphenol. Don’t be lured into buying a cheap nickel plated one. This is the good stuff:

https://www.dxengineering.com/parts/aml-83-1ap-2

Amphenols are always great. I had a slide-in PL-59 (non-threaded) and they worked really great for mobile / home setup with sliders. I'll end up buying that if I need it. As I follow the recommendation of the builder, he's explaining alot of things that he learned upon building the antenna. I even spoke to him in lightly painting or coating the antenna with a non metallic paints. Its all all in here but I couldn't find much time yet to sit down and concentrate on it. Its quite difficult doing all these things while working and taking care of other stuffs. They get in the way sometimes. Here is  the video....

http://www.jpole-antenna.com/2011/01/04/painting-the-j-pole-antenna/

[tcp2525]

21 hours ago, Sshannon said:

Use an angle connector to take the stress off but be sure it’s a high quality one like this Amphenol. Don’t be lured into buying a cheap nickel plated one. This is the good stuff:

https://www.dxengineering.com/parts/aml-83-1ap-2

I'm not doubting your expertise, but at $47.00 for two nickel plated brass Amphenols from DXEngineering, I'll stick with a nickel plated brass one from the south side of China for a quarter of the price. I don't think either of us will be able to pick out the Amphenol 100% of the time in a double blind test.

[OffRoaderX]

Just now, tcp2525 said:

I'll stick with a nickel plated brass one from the south side of China for a quarter of the price. I don't think either of us will be able to pick out the Amphenol 100% of the time in a double blind test.

As an unlicensed H.A.M. for over 40 years, I can tell you that you are 100% correct.

[Sshannon]

1 hour ago, tcp2525 said:

I'm not doubting your expertise, but at $47.00 for two nickel plated brass Amphenols from DXEngineering, I'll stick with a nickel plated brass one from the south side of China for a quarter of the price. I don't think either of us will be able to pick out the Amphenol 100% of the time in a double blind test.

Watch this video before you make up your mind, please. The difference is very measurable. It’s not an issue with SWR; it’s a problem with attenuation, aka insertion loss:

And I agree that without stressing your system you might never notice the difference. 
There are places that sell new old stock ones for $15 each or so. RF Parts or American Radio Supply appear in google searches. 
I was fortunate to inherit a few of the old silver plated ones from Amphenol. I absolutely understand the hesitation to spend $47 for a pair of these. 
 

[WRQC527]

52 minutes ago, tcp2525 said:

$47.00 for two

$65 (!) shipped to southern California. In some cases, I've had generic connectors fall apart or not seat correctly. Those are the two (rare) problems I've had with cheap connectors. The vast majority have been trouble-free.

[tcp2525]

1 hour ago, Sshannon said:

Watch this video before you make up your mind, please. The difference is very measurable. It’s not an issue with SWR; it’s a problem with attenuation, aka insertion loss:

And I agree that without stressing your system you might never notice the difference. 
There are places that sell new old stock ones for $15 each or so. RF Parts or American Radio Supply appear in google searches. 
I was fortunate to inherit a few of the old silver plated ones from Amphenol. I absolutely understand the hesitation to spend $47 for a pair of these. 
 

I watched the video and yes, I agree with you. But.... If someone is using SO-239s at 460 Mhz they're really not too concerned about a fraction of a db loss. What did he say, 3db loss through 10 connectors? So, using two in your system is going to be minimal. I have loads of old silver plated Amphenol connectors and happy with them because they are just good connectors. Everything I do on UHF goes through an N-connector if I can help it. I know hooking up the spectrum analyzer to measure return loss on a duplexer I can see the loss change as I tighten the N connector until it's fully seated.. That said, the ones DXE is selling are nickel plated brass and probably aren't that much better than Mr. Chung's nickle plated brass ones. I'm not knocking Amphenol's US made connectors, but you can easily reach the point of diminishing returns for hobby radio. If I were budget limited, I would rather invest in good feedline and use a marginal connector. The most loss is in long lengths of cheap coax.

Forgot to add, according to DXE specs the body of the connector is made of Zamac which is basically pot metal. The real question, does the Chinese adhere to the metallurgical formula for ZAMAK and does it really matter after it's nickel plated?

[WRQC527]

5 minutes ago, tcp2525 said:

If someone is using SO-239s at 460 Mhz

Pretty much every mobile GMRS and ham radio comes with SO-239s on the radio, in spite of their lossy nature on VHF and UHF. I have heard of folks changing the connectors on the radios to N, but most people I know just use what's there. My 2m, 440 and 1200 Mhz repeaters, with their associated duplexers, circulators and antennas, are all N connectors.

[tcp2525]

3 minutes ago, WRQC527 said:

Pretty much every mobile GMRS and ham radio comes with SO-239s on the radio, in spite of their lossy nature on VHF and UHF. I have heard of folks changing the connectors on the radios to N, but most people I know just use what's there. My 2m, 440 and 1200 Mhz repeaters, with their associated duplexers, circulators and antennas, are all N connectors.

Agree. I'm not that anal were I'm going to change the connector on the radio.

[Sshannon]

16 minutes ago, tcp2525 said:

Agree. I'm not that anal were I'm going to change the connector on the radio.

I absolutely agree, but if I ever must change the connector on the radio I’ll put on an N female.

M&P advertises that their PL-259 connectors are nearly as good as N males.  I haven’t seen test data, but again they’re not cheap.

[CudjoeCane]

Back to the original topic.

Our GMRS club here in the Florida Keys has purchased three Comet CA-712EFCs for southernmost repeater sites.  The first one went up in Marathon and has performed reasonably well.  I also have one at my base, where I am able to hit a Miami repeater 75 miles away fairly often - though definitely not 100% of the time.

   

 

[tcp2525]

6 hours ago, Sshannon said:

I absolutely agree, but if I ever must change the connector on the radio I’ll put on an N female.

M&P advertises that their PL-259 connectors are nearly as good as N males.  I haven’t seen test data, but again they’re not cheap.

 

I thought about it, but I'm too damn lazy!

Just the inherent design of the PL-259 it will never be as good as an N connector.

[WRKC935]

Yeah, there have been 800Mhz radios that were produced with PL-259 connectors.  Sure there is some loss.  The N connector is a better option, but it's a situation where the performance difference isn't significant enough to matter in most real world situations.  There are people that believe that little bit of loss is going to keep them from being able to communicate, or give them an edge on getting some rare DX contact in the case of the ham radio guys.  But the truth is you would never notice.  But I will say that installing PL259 connectors on RG-8 sized cables is a pain as opposed to an N connector.  We use the Times Microwave LMR400 / LMR600 EZ connectors and that specific cable at work as a standard unless heliax is used, and the connectors go on quickly with the proper prep tool.

 

[Sshannon]

2 hours ago, WRKC935 said:

Yeah, there have been 800Mhz radios that were produced with PL-259 connectors.  Sure there is some loss.  The N connector is a better option, but it's a situation where the performance difference isn't significant enough to matter in most real world situations.  There are people that believe that little bit of loss is going to keep them from being able to communicate, or give them an edge on getting some rare DX contact in the case of the ham radio guys.  But the truth is you would never notice.  But I will say that installing PL259 connectors on RG-8 sized cables is a pain as opposed to an N connector.  We use the Times Microwave LMR400 / LMR600 EZ connectors and that specific cable at work as a standard unless heliax is used, and the connectors go on quickly with the proper prep tool.

 

For all its imperfections, the PL-259 is much more durable than the N connector. That alone might make it worthwhile living with the disadvantages.  I have seen the tiny brass fingers on an N female connector broken, presumably because someone attempted to plug in a PL-259.  And whoever adopted the same thread diameter and pitch for both should be chastised.  I would love to know that history.