MTR3000 Repeater

[zerodayjames]

@MTS2000des
Yes I was also looking into the coordination requirements which are recommended but not required. I am a technologist and want to learn and experiment. I also understand the legalities and have respect for the airwaves and do not plan on putting up a rogue repeater that is going to interfere with other HAMs and businesses that are already in place. I feel this goes without saying, but thought I would mention it anyway.
As with all my other expensive hobbies... this is proving to be the most expensive and extensive. The expensive part not so fun but extensive is exciting as it's another never ending rabbit hole like cyber security. I will never be bored, just need to balance time for kids and other responsibilities lol

@mmckenna
Initially I wanted the versatility of two antennas so that I can more easily swap around frequencies without having to tune a duplexer but it's proving more difficult considering my location space. I will be taking the duplexer route.

Thanks. Agreed. Self hosted experimental will be the path for now at least so I can get familiar and maybe get a raise before considering 3rd party hosting on the mountain.

40 - 50 ft. is my safest max height taking power lines into consideration. I would love to throw up a 200 ft. crank up but you can't have it all.
Man I guess I'll keep looking around for more affordable repeaters and duplexers. Can't seem to find anything better than those prices online right now.

@kayn1n32008
Yep these Wouxons suck. I was following Randy's build on YouTube (notarubicon) but should have done more research before pulling the trigger. And here we are, doing more research... I'll stick with a duplexer and use my other tower for HF maybe. Haven't gotten into that world just yet.

 

[rneals]

Also I am not seeing any MTR3000s for better than $2000.00... Any resources to used radio sellers would be awesome.

I was surprised to see a report of people buying MTR3000 for a maximum of $800.

The best price I've achieved is $1100 in a public auction with a sample size of having bought 5 at various times.
On eBay they are typically listed around $2500-$3,000 (I said listed, not what would be a good price to pay)
An important note on the MTR2000.. The high powered VHF MTR2000 is widely found in the 150-174 MHz split, but the lower split best for the 2M ham band is now like finding a unicorn. Some are being sold on eBay as being modified. I think what this means is that they installed a jumper and told the microprocessor it is the other split, but whether they made any RF changes is unknown.

The 30/40 watt VHF MTR2000 are capable of supporting the entire 138-174 band.
Watch for DC powered repeaterd in the 30/40 watt versions, and watch for 12V volt vs 24 volt - they dont mark it on the repeater, so you have to consult part number and the manual. 24v into a 12v MTR2000 does not always turn out well.

The MTR3000 is also broadband supporting entire 138-174 band.

 

[mmckenna]

Can't seem to find anything better than those prices online right now.

With Motorola gear, you are always going to pay a premium to have that brand name.
With used Motorola gear, you are competing against people that really want the brand name and are willing to pay extra for it.

You can get brand-spankin-new Kenwood DMR/analog repeaters for $2200 list (probably less if you shop around) and you don't have to deal with some 20+ year old cast off. There are newer Kenwood models that are out now (NXR-1700/1800) that are similarly priced.
No reason to pay a premium for a Motorola repeater that requires an old laptop to program. You can get stuff from this century cheaper.

 

[zerodayjames]

@rneals
Yeah I'm not finding that great of prices either. And I don't think that can only be written off to "inflation"...

Yes that 2 m 100W MTR2000 is truly a unicorn. Fortunately I decided to go UHF as I was getting better results when running tests in my location on the 70 cm band as opposed to 2 m.

@mmckenna
I hear you. All these Motorolas are listed top dollar which is crazy because some of them have been up for months and nobody took the bait.

I'm going to look into Kenwoods and some other new model options. It would be nice to not have to use a dinosaur computer and old documentation to maintain and support. Worst case though I can just spin up a virtual machine.

 

[kayn1n32008]

Watch for DC powered repeaterd in the 30/40 watt versions, and watch for 12V volt vs 24 volt - they dont mark it on the repeater, so you have to consult part number and the manual. 24v into a 12v MTR2000 does not always turn out well.

100w=24v low powered should be 12v AFAIK.

 

[jeepsandradios]

Fortunately, that's NOT the way it works in Illinois and the nine surrounding states.

www.ilra.net

But thats not law. He can do as he feels fit as long as he doesn't interfear.

 

[kayn1n32008]

I want to look into the ability to pass AES 256 encryption.

Steer clear of any sort of MMDVM board/RPi based DMR solution. Do gooder hamsters don't support encryption in the hammy digital boards.(Brandmeister ect.)

 

[kayn1n32008]

But thats not law. He can do as he feels fit as long as he doesn't interfear.

Where I live, after the inevitable 'No pairs available' reply to a coordination request, we will do our own research and figure out an actual unused pair and tell them were using it. Some places are still stuck on 30kHz channels on VHF and 25kHz channels on UHF

 

[Ubbe]

@MTS2000des
I will be taking the duplexer route.

What's important are a notch filter for the TX frequency on the RX antenna. Having the antennas separated should work when using a much cheaper notch filter than a complete duplexer. You can probably let PAR Electronics do a $100 filter for you to try.

/Ubbe

 

[zerodayjames]

I’ve been monitoring pairs for the last few days and will continue as I zone in more towards which antenna/duplexer to run with. I did find this duplexer and had a couple questions.

https://www.talleycom.com/images/pdf/SINQ301GC-1.pdf

1. I’ve been advised to ensure that it is capable of band pass/band reject. This one does not indicate that. But will it still do the job?

2. The listing I found is for a cabinet enclosed model. It is pretty big so I will have to find a proper location for it. Will putting it in the attic be an issue as far as heat in the summer? Summers get up to 106F sometimes so I can only imagine how hot it is up there.

 

[Ubbe]

1. I’ve been advised to ensure that it is capable of band pass/band reject. This one does not indicate that. But will it still do the job?

The diagram show two wide bandpass ranges and two sharp notches, so it is a normal duplexer.

My experience are that all filters needs a fine tune at the site to get it perfected. But if you do not have at least a signal generator and a 30-40dB T-attenuator and a dummy load then you will have to trust the original off-site tuning to be close enough.

/Ubbe

 

[MTS2000des]

2. The listing I found is for a cabinet enclosed model. It is pretty big so I will have to find a proper location for it. Will putting it in the attic be an issue as far as heat in the summer? Summers get up to 106F sometimes so I can only imagine how hot it is up there.

You can bet your bottom dollar duplexers will detune in presence of wild temperature swings, this is why equipment is typically located in temperature controlled shelters. Not to mention, most of the upper operating limit of most FNE is 140F and most modern gear will fold back output power or just shut down altogether in overtemp.

 

[kayn1n32008]

I’ve been monitoring pairs for the last few days and will continue as I zone in more towards which antenna/duplexer to run with. I did find this duplexer and had a couple questions.

https://www.talleycom.com/images/pdf/SINQ301GC-1.pdf

1. I’ve been advised to ensure that it is capable of band pass/band reject. This one does not indicate that. But will it still do the job?

2. The listing I found is for a cabinet enclosed model. It is pretty big so I will have to find a proper location for it. Will putting it in the attic be an issue as far as heat in the summer? Summers get up to 106F sometimes so I can only imagine how hot it is up there.

That is a BpBr duplexer. Look at the ResLoc series from Sinclair. 4 cavities on UHF will work just fine.

 

[zerodayjames]

@Ubbe
Normal duplexer, as in it is BP/BR?
I am looking into the necessary equipment to properly tune now. I saw the Rigol DSA815-TG which is a bit pricey but I figure it will be a proper investment in the long run. I understand that I will need two dummy loads or just one? Also I did not find any info on using a T-attenuator when tuning. What does this do/what will I need it for? Is this a base line of the equipment I will need?

@MTS2000des
Yep. Max temp on this thing is 140F. I will find a better location than the attic.

@kayn1n32008
If this one is BpBr then I might roll with it. Found a brand new open box one for around $700.

I am officially at a crossroads now. I can either purchase the radio and duplexer separately and learn to program the radio and tune the duplexer and invest in all the equipment to set it up and maintain. Or I can just buy it as a package deal, pretuned and cross my fingers that it doesn't get messed up during shipment and install.

 

[Ubbe]

You have some good instructions in this thread.
I believe all site radio technicians are following those exact steps in that instruction.

If you have a signal generator and a cheap $100 VNA then that's all you'll need, if you have one dummy load that can handle the TX power, a power meter and that T-connector 30dB isolator, that can be a standard T-connector with a 30-40dB attenuator on one leg that goes to the signal generator. You tune a duplexer for best bandpass of its own frequency and biggest notch of the other frequency and fine tune at the site for best sensitivity while trying to maintain a high TX power as possible without compromising RX performance.

/Ubbe

 

[kayn1n32008]

@kayn1n32008
If this one is BpBr then I might roll with it. Found a brand new open box one for around $700.

I am officially at a crossroads now. I can either purchase the radio and duplexer separately and learn to program the radio and tune the duplexer and invest in all the equipment to set it up and maintain. Or I can just buy it as a package deal, pre-tuned and cross my fingers that it doesn't get messed up during shipment and install.

That one is a BpBr Duplexer, you would want the Q301GC-4 model that covers 420-450MHz. They are an excellent choice of duplexer.

 

[kayn1n32008]

https://www.talleycom.com/images/pdf/SINQ301GC-1.pdf

The listing I found is for a cabinet enclosed model. It is pretty big so I will have to find a proper location for it. Will putting it in the attic be an issue as far as heat in the summer? Summers get up to 106F sometimes so I can only imagine how hot it is up there.

That does take up a fair bit of space because it is individual cavities, and provides at least 100dB of isolation. It is an excellent choice, but the trade off is it takes up more space than a ResLok

https://cdn.shopify.com/s/files/1/0531/8970/5898/t/7/assets/Q3330C-3-Spec-Sheet.pdf?v=1615990432

The duplexer I just linked, takes up far less space in the rack, but trade off a bit of isolation. One thing to note, I have always found Sinclair duplexers to always exceed their isolation specs when tuned.

I would suggest keeping the repeater and duplexers inside your house and increase your feedline run a bit to keep the repeater and duplexer in a climate controlled area. Do not use LMR400 or any sort of foil/braid coax. Hardline is the way to go with feed line

 

[zerodayjames]

I would suggest keeping the repeater and duplexers inside your house and increase your feedline run a bit to keep the repeater and duplexer in a climate controlled area. Do not use LMR400 or any sort of foil/braid coax. Hardline is the way to go with feed line

I can find a better location for this that is climate controlled. I think the space drawback is worth the isolation gain in my case.

I am currently using this cable:

Messi & Paoloni Extraflex Bury 13 Premium .500" Coax Cable - Custom Length (per foot)

Messi & Paoloni Extraflex Bury 13 premium coaxial cable is specifically made for direct burial and outdoor use and is a must-have for the most ambitious installations. It can be ordered in custom lengths according to your needs.

www.buytwowayradios.com

Will this work or is there a more ideal choice? I will have to purchase more cable when I extend the length of the tower anyway.

 

[zerodayjames]

You have some good instructions in this thread.
I believe all site radio technicians are following those exact steps in that instruction.

If you have a signal generator and a cheap $100 VNA then that's all you'll need, if you have one dummy load that can handle the TX power, a power meter and that T-connector 30dB isolator, that can be a standard T-connector with a 30-40dB attenuator on one leg that goes to the signal generator. You tune a duplexer for best bandpass of its own frequency and biggest notch of the other frequency and fine tune at the site for best sensitivity while trying to maintain a high TX power as possible without compromising RX performance.

/Ubbe

Thank you I'll have to get everything together and follow this thread. Would using the tools you listed, signal generator, VNA, power meter and T-Connecter be used instead of the Rigol spectrum analyzer. Just trying to wrap my head around this.

 

[kayn1n32008]

I can find a better location for this that is climate controlled. I think the space drawback is worth the isolation gain in my case.

I am currently using this cable:

Messi & Paoloni Extraflex Bury 13 Premium .500" Coax Cable - Custom Length (per foot)

Messi & Paoloni Extraflex Bury 13 premium coaxial cable is specifically made for direct burial and outdoor use and is a must-have for the most ambitious installations. It can be ordered in custom lengths according to your needs.

www.buytwowayradios.com

Will this work or is there a more ideal choice? I will have to purchase more cable when I extend the length of the tower anyway.

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