MTR3000 Repeater

[zerodayjames]

I'm not familiar with that cable. generally, for repeater installations, you want to use hardline.

35422-25

LDF4-50A, HELIAX® Low Density Foam Coaxial Cable, corrugated copper, 1/2 in, black PE jacket, phase stabilized.

www.commscope.com

Something like this would be a minimum. Depending on total length between duplexer and antenna. For runs of 30m or less, LDF4-50 would be the minimum I would recommend

Total length is about 45 ft. So shouldn’t be a problem. Hardline meaning solid core? If that’s the minimum what would be the premium? Gotta weigh out my options.

Also opinions on used vs new duplexers?

 

[MTS2000des]

LMR400/600 type cable should be avoided. LDF-4-50A is what you want. As far as used duplexers, nothing wrong with a used set of cans provided they aren't damaged. Shipping them is where that usually happens but they can be damaged internally if they take a lightning strike.

Remember that you will want to tune your duplexers with your antenna, feedline and radio once they arrive. While they can be tuned on the bench, the rest of your system can impact tuning and you can't trust that the UPS/FedEX driver didn't play package toss with your cans.

 

[mmckenna]

Hardline meaning solid core? If that’s the minimum what would be the premium? Gotta weigh out my options.

The issue with the LMR series cables is that it has an aluminum tape shield with a copper braid over it. Dissimilar metals + a bit of moisture and you have a dielectric joint that will make all kinds of interference on a duplex system.

"Minimum" is kind of hard to answer. There's a lot of crappy cables you could use that would technically work, but would be kind of silly since it will really reduce performance of your system. For a small 10 watt mountain top repeater where it's 10 feet from the repeater to the antenna, I've run 3/8" superflex Heliax.

1/2" Heliax (LDF4-50) is a manageable size cable, reasonably affordable (considering all the other money you are spending on this), and will work well.

"Premium" is also hard to answer. How much money do you have? Whats the run like? How much room do you have for making very wide bends with the cable (minimum bend radius is a thing….). I've got 7/8" Heliax on 40 foot runs for 800MHz repeaters. I've got 1 5/8" Heliax for 200 foots runs for a trunked system. You can go larger, but it gets kind of stupid at some point.

1/2" Heliax is more than sufficient for a 50 foot run on VHF/UHF for amateur use. The reduced loss of larger cables will be kind of a moot point since your antenna is so low.

Also, when looking at these cables, make sure you consider the cost of the connectors. 1/2" Heliax connectors can run you $50-$60 new, each. Installing connectors on this cable is different than braided cables, also.

 

[kayn1n32008]

Total length is about 45 ft. So shouldn’t be a problem. Hardline meaning solid core? If that’s the minimum what would be the premium? Gotta weigh out my options.

Also opinions on used vs new duplexers?

Hard line meaning solid, continous shield.

They have minimal loss, and with a continous solid shield, reduces PIM, Losses and is what should be used for repeater Instalations.

What I don't understand, is your looking at buying a decent repeater, and a decent duplexer, but you want to cheap out on feedline.

 

[zerodayjames]

LMR400/600 type cable should be avoided. LDF-4-50A is what you want. As far as used duplexers, nothing wrong with a used set of cans provided they aren't damaged. Shipping them is where that usually happens but they can be damaged internally if they take a lightning strike.

Remember that you will want to tune your duplexers with your antenna, feedline and radio once they arrive. While they can be tuned on the bench, the rest of your system can impact tuning and you can't trust that the UPS/FedEX driver didn't play package toss with your cans.

Got it. Ordered the duplexer now. Will look into the proper tuning equipment and will definitely be coming back with questions once I have hands on all the gear.

 

[zerodayjames]

The issue with the LMR series cables is that it has an aluminum tape shield with a copper braid over it. Dissimilar metals + a bit of moisture and you have a dielectric joint that will make all kinds of interference on a duplex system.

"Minimum" is kind of hard to answer. There's a lot of crappy cables you could use that would technically work, but would be kind of silly since it will really reduce performance of your system. For a small 10 watt mountain top repeater where it's 10 feet from the repeater to the antenna, I've run 3/8" superflex Heliax.

1/2" Heliax (LDF4-50) is a manageable size cable, reasonably affordable (considering all the other money you are spending on this), and will work well.

"Premium" is also hard to answer. How much money do you have? Whats the run like? How much room do you have for making very wide bends with the cable (minimum bend radius is a thing….). I've got 7/8" Heliax on 40 foot runs for 800MHz repeaters. I've got 1 5/8" Heliax for 200 foots runs for a trunked system. You can go larger, but it gets kind of stupid at some point.

1/2" Heliax is more than sufficient for a 50 foot run on VHF/UHF for amateur use. The reduced loss of larger cables will be kind of a moot point since your antenna is so low.

Also, when looking at these cables, make sure you consider the cost of the connectors. 1/2" Heliax connectors can run you $50-$60 new, each. Installing connectors on this cable is different than braided cables, also.

1/2" Heliax sounds like the way to go. I will have to get some new lightning arrestors as the ones I have currently are PL259 and I want to minimize as many type N adapters as I can. Sheesh 1 5/8" Heliax sounds intense! I'm an electrician and that stuff sounds like getting into the 500 MCM type runs. Heavy duty stuff but yes, overboard if you don't require it. My run is 35 ft. from the antenna to the lightning arrestor, then another 10 ft. from the arrestor to the duplexer.

 

[zerodayjames]

Hard line meaning solid, continous shield.

They have minimal loss, and with a continous solid shield, reduces PIM, Losses and is what should be used for repeater Instalations.

What I don't understand, is your looking at buying a decent repeater, and a decent duplexer, but you want to cheap out on feedline.

I don't want to cheap out on the feed line. I was actually asking about the "premium" grade of hardline as to not settle with "minimum." As far as lightning arrestors, are there any specific types/brands that have less loss? Or ones that should be avoided?

 

[mmckenna]

1/2" Heliax sounds like the way to go. I will have to get some new lightning arrestors as the ones I have currently are PL259 and I want to minimize as many type N adapters as I can. Sheesh 1 5/8" Heliax sounds intense! I'm an electrician and that stuff sounds like getting into the 500 MCM type runs. Heavy duty stuff but yes, overboard if you don't require it. My run is 35 ft. from the antenna to the lightning arrestor, then another 10 ft. from the arrestor to the duplexer.

Most of the commercial gear you will see is going to be N connectors. It's good to get rid of the UHF connectors if you can, especially if this is going to be a UHF repeater.

1/2" Heliax sounds like the right stuff for you. You may even want to consider their "superflex" product for the 10' connection.

 

[kayn1n32008]

1/2" Heliax sounds like the way to go. I will have to get some new lightning arrestors as the ones I have currently are PL259 and I want to minimize as many type N adapters as I can. Sheesh 1 5/8" Heliax sounds intense! I'm an electrician and that stuff sounds like getting into the 500 MCM type runs. Heavy duty stuff but yes, overboard if you don't require it. My run is 35 ft. from the antenna to the lightning arrestor, then another 10 ft. from the arrestor to the duplexer.

There should be ZERO PL-259/SO239 connectors in your repeater system. And ZERO N<->PL259/SO239 Adaptors either.

PL259's have no place in a properly built repeater system.

 

[kayn1n32008]

I don't want to cheap out on the feed line. I was actually asking about the "premium" grade of hardline as to not settle with "minimum." As far as lightning arrestors, are there any specific types/brands that have less loss? Or ones that should be avoided?

Polyphaser. With N-Female connectors.

Premium cable? I mean 1-5/8" hardline, but at 50', it's overkill for a back yard repeater. 1/2" hardline will work just fine.

 

[zerodayjames]

And for the connections from the repeater to the duplexer? Will 3 ft. runs of RG400 suffice?

 

[Ubbe]

1/2" with copper foil and a solid core are what are used in most installations. When doing installations for a customer you would want the best components and not anything that suddenly will need you to replace a coax that have gone bad after a couple of years that will create downtime for a crucial system. For personal use you can accept to use cheaper stuff and might even be beneficial as you have to diagnose issues and solve them, making you improve your skill and experience level. But if you plan to rent out airtime then you of course will want it to run as problem free as possible.

/Ubbe

 

[mmckenna]

And for the connections from the repeater to the duplexer? Will 3 ft. runs of RG400 suffice?

That's commonly used for jumpers.

 

[kayn1n32008]

And for the connections from the repeater to the duplexer? Will 3 ft. runs of RG400 suffice?

The shorter the better. RG400 is fine.

 

[zerodayjames]

Thanks for all the guidance guys. I was able to find a new Sinclair 6 can duplexer and a Motorola MTR3000 that was pulled from a school. Got both for just over $2200.00 total. If it wasn’t for y’all I would have dropped WAY more money on these two components previously. 🙏🏼

 

[zerodayjames]

Am I on the right track here regarding my feed line?

Coax:

CommScope - 1/2" 50 Ohm Superflex Coax Cable - FSJ4-50B

CommScope - 1/2" 50 Ohm Superflex Coax Cable - FSJ4-50B The Andrew FSJ4-50B 1/2 inch 50 Ohm coax cable is superflexible and less prone to kinks because of its spiral copper corrugated outer conductor. The superflex cable features a 1.25 inch bending radius. This coaxial cable transmission line...

www.venus-comm.com

Connectors:

CommScope - 1/2" Superflex - N-Male Captivated Connector- F4PNMV2-HC

CommScope - 1/2" Superflex - N-Male Captivated - F4PNMV2-HC ANDREW N Male Connector for FSJ4-50B superflexible cable. Hex head, captivated center pin. Silver body & gold plated Pin. Version 2. RF Connector N Male RF Connector Body Style Straight RF Impedance 50 Ohms Outer Contact Attachment Type...

www.venus-comm.com

Arrestor:

PolyPhaser - Flange Arrestor, N/F - IS-50NX-C0

PolyPhaser - Flange Arrestor, N/F - IS-50NX-C0 POLYPHASER 1.5-400 MHz general coverage flange mount protector. 50,000 amps surge <10mJ throughput energy. Power rating based on frequency. N female connectors. Mount Type Flange Frequency Range 1.5-700 MHz Turn On Voltage 600 VDC Nominal Insertion...

www.venus-comm.com

Only concern was the my current setup utilizes a grounding bushing on the arrestor. This one does not.

 

[a417]

Only concern was the my current setup utilizes a grounding bushing on the arrestor. This one does not.

This should help you...

 

[mmckenna]

Am I on the right track here regarding my feed line?

Looks good to me.

Only concern was the my current setup utilizes a grounding bushing on the arrestor. This one does not.

That Polyphaser has a bracket that is part of the module. That usually gets bolted to a ground buss at the cable entrance. If you don't have that, you can run a piece of 6 gauge wire with a ring terminal to it and use that to connect to ground.

 

[zerodayjames]

Looks good to me.



That Polyphaser has a bracket that is part of the module. That usually gets bolted to a ground buss at the cable entrance. If you don't have that, you can run a piece of 6 gauge wire with a ring terminal to it and use that to connect to ground.

Gotcha. I saw others pictured with the bracket, just wasn't sure if this one had it. My #6 is already routed there I'll just need to find the right size ring terminal.

 

[prcguy]

There should be ZERO PL-259/SO239 connectors in your repeater system. And ZERO N<->PL259/SO239 Adaptors either.

PL259's have no place in a properly built repeater system.

But that's what Motorola has supplied on their UHF duplexers for many years and they work just fine. A typical UHF Motorola 1500 series and its replacement have six PL-259s and seven SO-239s.