Radioguy7268

Those Midland/Retevis repeaters have a very small internal duplexer that can barely create any decent isolation when the repeater is cranking more than 5 watts. There is no magic bullet. You are never going to find a good, cheap, compact duplexer that passes 95% of your transmitter power and still gives you 90+ dB of isolation. It doesn't exist. Every rookie with a wattmeter wants to get the MAXIMUM possible output power out of their repeater. I mean, 50 has to be better than 5, right? In my opinion, the MOST important spec in a repeater system is the isolation between transmit and receive. Especially if you're using portable radios out in the field that can talk back in with 4 or 5 watts of transmit power. What good is it to key up your repeater with 10 or 15 watts of power when you introduce 3 or 4 dB of desense into the system? 3dB of desense on the receiver just made your 4 watt portable into a 2 watt portable, and how well is that going to work? Better isolation = a better repeater. Want to have a cheap repeater? You will get what you paid for. Cheap is rarely good.

Either I'm not understanding what you're saying, or there's an issue I'm not seeing. You seem to be saying that you cannot get the MTR to key (and pass audio) from a portable, but in one of your posts, you state "I can key the MTR from a radio, the "receive" light comes on and stays solid until I unkey the radio. The received audio (in BASE station mode) does not get passed the controller, into the transmitter." When that receive light comes on (I'm assuming we are talking about the Rx LED on the MTR2K) - does your MTR also have a Transmit LED? To me, "keyed" means transmitting. What I do see is that your homemade cable does not appear to be strapped for PTT. You probably need to provide me with a diagram of your cable pinout (both sides) in order to diagnose what you're doing wrong. C10 needs to be pulled to ground to key the MTR in Base mode. You also need to properly map the Wireline Audio via RSS in order to get audio to pass when using the wireline audio - and by doing it that way, you can use the MTR's internal PL/DPL. Wireline audio is the way to go. When you say that you've "attempted to adjust the audio" for the Wireline according to the Station Alignment - what did you end up with for levels? And, what did you use to input the 1000 Hz tone? There's really no attempting - you either set the levels or you do not, and you need to have a way to read exact deviation levels on the output.** I have never needed to use any external amplifier to drive the input audio on an MTR2000. The station itself is plenty sensitive and responsive. **I have found that you need to lie a little to the MTR during the wireline Station Alignment when giving the levels measured in order to actually achieve full deviation. ie: You need to understate the deviation values actually measured by a few hundred Hz when inputting your results - so that the MTR will slightly "over-drive" and give you the full deviation you desire.

When the MTR2K is in "Base" mode, you need to have a signal to actually key the machine to act as a repeater. It will not automatically repeat just because you've got a PL/DPL or CSQ light on. I'm not seeing that you have anything strapped to C10. It appears that you need to strap Pin3 from your URIx to C10 on the J5. C10 needs to be pulled to ground in order to key the MTR2K when it's in Base mode.

Again, if you want to use DMR for Digital simplex, the FCC already offers you a service for this choice. Go get a part 90 license, talk on DMR simplex all day long. Make sure you license it as an MO6/FB6 Private Carrier, and then all your friends and family (plus anyone else you want to count as a 'subscriber' under your license) can join along for one 10 year term. As a bonus, you can use encryption, run a repeater, and even pump out more than 50 watts. There are no GMRS Part 95 radios that will do Digital today, so unless you want to wait for a possible rule change, wait for manufacturers to respond to the changes and build GMRS digital radios, you would end up using Part 90 equipment anyway. I really don't understand the resistance to using what's already available today. If you want to use DMR, then use DMR - it wasn't like you were going to be using it to talk with existing analog GMRS users anyway.

Using the Wireline audio is the way to go if you want the MTR2K to do the PL/DPL. There is a procedure to follow to set up the levels on the wireline audio if it was never before configured. That requires test equipment and some know-how, but the procedure is in the manual. Go read up at repeater-builder.com : https://www.repeater-builder.com/motorola/mtr2k/more-mtr2k-int/mtr2000-interfacing-followup.html According to the "Installation and Operation manual", System Connector pin C10 (External Tx. keying signal) states: "Grounding Ext. PTT pin causes Tx to key. 5.0Vdc on pin when Tx is not keyed. Note: To transmit signaling code (PL / DPL) by external PTT, it should be mapped (via RSS) to Wireline, and external modulation input should be routed to wireline." They should have made the language a bit stronger, as this information MUST be followed exactly in order for this to work. On the "Personality", "Channel Information", "PTT" page, set the "External PTT mapping" to "Wireline". IT WILL NOT WORK IF YOU DO NOT MAP THE AUDIO!! This is the only option that will pass external audio and internal PL/DPL. Make sure you UNCHECK the box next to "Wireline" in the "PTT Timeout Timer" area so the station doesn't time out when the external repeater controller keys it.

You also have the issue that while DMR is a basic digital standard, every manufacturer has their own flavors that they have built on top of the standard to add features for their user base. So when one repeater owner decides to add Restricted Access for Security, and then another one wants to add enhanced Privacy/encryption, another will decide to implement GPS Location. Good luck trying to them all on board with your DMR dream. As already mentioned before - go get yourself an FB6 Private Carrier license on Part 90 if you want to do DMR. If you're determined that it needs to be done on GMRS frequencies - then go write up a petition for rule change & wait around for 5 or 10 years to see if the FCC responds.

Brothers from another mother. Who's pulling DNA samples to check? But yeah, that's kind of flaunting it. Unless the Front Range EE group is one of those old Grandfathered commercial operators under Part 95 back from the days of Class A licenses...

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.

Who are you talking to and what do they carry for a radio? I believe you said you've got relatives 15 miles away. If they carry portables - it is MUCH more important that your desired repeater can hear those 4 or 5 watt portables from 15 miles away than it is for your desired magic repeater to punch out 50 watts so you can reach them. Pay more attention to how well your repeater can receive - and you'll end up with a better system. Wouxun mobiles built into a repeater are twice as expensive and half as good as other solutions available. Search up the term desense, and you'll see what's going on.

Is there anything that limits an individual to one station? Many folks have multiple repeaters operating under one call sign. My nephew 2 states over uses my repeater (and call sign) to run his family farm.

If you are talking to 4 watt portables - who cares how much power gets through the duplexer? A "tight" duplexer tuning that loses more dB is preferable to a sloppy duplexer tune job that gets more power/less dB loss. Remember, you are using the duplexer to achieve isolation between the transmit and receive frequencies. Isolation is your key measurement - NOT power throughput. On most of these rigs built with an inexpensive notch AKA compact duplexer and 2 mobile radios, turning DOWN the transmit power will result in better overall range, less desense, and longer equipment life.

Radio waves don't know the direction in which they are heading - ie: being transmitted or received. The signal is the signal. The trouble you originally described would not be due to antenna height. Why go through the trouble of raising up the antenna, but avoid doing a simple 5 minute troubleshooting test and report on the results?

The main reason 90% of repeaters use a duplexer is because of ISOLATION, not because of power loss. As others here have said, yes you can work it with 2 antennas, but you will likely still need additional filtering. If all you can measure is wattage & SWR, you are never going to appreciate what true isolation and improved receive sensitivity (and selectivity) can do for your repeater. How's that saying, when your only tool is a hammer, every problem looks like a nail? I guess in the radio world, when all you have is a watt meter, every problem looks like a lack of power. If you have enough RF power to reach out to whoever you want to talk with, but they can't reach you back because your repeater's receiver is being drowned out due to poor isolation (likely from your own transmitter) - then what's the point? You've now got a bunch of time and money invested in a one way paging system. The point of having mobile transmitters is to allow them to talk back. I'd gladly give up 3 dB of transmit power in a duplexer if it offered 100dB of isolation. Most of the affordable compact notch duplexers will only give you about 65dB of isolation with a 5 MHz split. Add a tuned bandpass cavity or two to the receive side, you'll pick up even more isolation - and you'll still be ahead of the 45 or 55 dB isolation of a split antenna system with 20 or 25 ft. vertical spacing. Oh yeah, and if you do a split antenna system, don't use braided cable for your coax. You'll leak somewhere around 6-10% of the signal with most decent brands - even worse with the cheap knockoffs that use a loose weave for the coaxial braiding. Think about where that 6-10% of your signal is going as it travels up the tower. Even the real Heliax hardline has some RF signal leakage, but it's about as good as you can get in an imperfect world.

It's advertised as 11.9 dBi In a typical vertical collinear antenna, you can gain 3dB of gain every time you double the number of stacked elements - or you can just tell the advertising guy to add 3 more to the gain number by stating gain measured as dBi. dBi is gain measured against a theoretic isotropic antenna - which isn't the real world.

OK, now I understand a little better about what you're asking. In my world, terminology of a "base" station means you are transmitting on the lower (462.x) frequency, and speaking in simplex to other people on the same 462.x channel. A Control station is what you use to work a distant repeater, and those transmit on the higher 467.x frequencies. Then they receive on the 462.x The appearance of a Base or Control station can be the same (a mobile radio on a desktop) but the programming and functionality would differ. You're not going to work a distant repeater by transmitting on the Base (462.x) frequency. If you have a repeater using a duplexer, you're not going to be able to do what I suggested (plugging in a mic) to do what you want. If you key your Control station on a 467.x frequency that's the same as your repeater, you're going to overpower the receive side of your repeater. Not recommended.

If the two radios are not keyed at the same time, they should not interfere with each other. If the repeater and the base would be keyed at the same time, the stronger signal from the base would likely walk all over the repeater's output. Assuming you would be the one in control of the base radio, why would you knowingly create your own interference? I guess my biggest question is "why?" Other than being in love with the concept of a small 5 watt self contained repeater, you could just put in a larger and higher power repeater using the existing antenna & line that you've already got in place, and then plug a mic into the repeater so you could use it as a dispatch point. Pretty much every mid-range commercial repeater offers that option, especially if they're made from two mobile radios - like a CDR700 for example:

Microwaves were invented during Roman times - Emperor Nero cut off some dude's fingers & left him with only his thumbs. That same guy (Digitalis Minimus) went on to invent the UHF PL-259 connector, for hams who were 'all thumbs'. True story.

Double check your programming on both sides (repeater and mobile/portables). I'd think that it's more likely a fat-fingered typo than a problem with the antenna & line. It's either that, or you're describing a de-sense issue in a unique way... The suggestion of testing in simplex with another radio hooked up in place of the repeater is a real good test for basic troubleshooting. If a portable works just fine in simplex mode, then there's likely a problem with the repeater or duplexer. If you experience the same problem when testing with a portable - then you know you're looking at a coax/antenna issue.

Assuming you don't need to hire a climbing crew to install that new antenna & hardline, then yes, the price of a 2nd antenna & line is probably much less than a tuned transmit combiner & receive multicoupler system. Having two repeaters close in proximity and close in frequency can lead to some issues if you're just using compact (inexpensive flat pack notch) duplexers that have very little protection from adjacent signals. Meaning that if you try to use the 462 GMRS repeater at the same time as the 463 Part 90 machine, you could create some of your own interference. If you're not keying both machines at the same time, then you're probably good to go. If you want to have both repeaters keyed up at the same time, you'll either need to use better quality filtering (think high end $1500+ bandpass/band reject cavity duplexer per machine) or a quality transmitter combiner system. Not many 'hobby' type systems can cost justify a combiner.

You set Pin8 to PL/DPL - CSQ detect on the Repeater's RX (receiver) radio. This is how you make sure that only intended transmissions (from your group's properly programmed mobile/portable units) will be received on your repeater's 467.xxx frequency. The transmit radio is then being told to key up upon that receive decode action. There is no need for your Transmit radio to detect incoming PL/DPL. It's function is to transmit - but you should still generate a PL tone or DPL code for the Transmit output. Some people try to program the receive and transmit radios the same way - with the idea that they'll be able to swap them around more quickly once the transmit radio burns up. IMHO that's the wrong move. My take would be to program each radio for it's intended use, and set it up properly the first time. You can always save & store the codeplugs for later use to reprogram or re-purpose a unit via the Clone function. If you take the time to set things up properly - AND TURN DOWN THE TRANSMIT POWER - the repeater will live longer, users will be happier, and you will have more time to go about improving the system instead of thrashing around trying to figure out what broke this time. Repeater-builder.com is an excellent resource for anyone trying to build, setup, or program their own repeater.

Well, First you should make sure that is what you want to do. From what you've said, it's possible that you're looking for a multi-tone panel to separate user groups on your repeater by PL tone. Adding an external tone panel to your repeater is not quite at the level of simple, but it has been done, and there are panels (and cables) designed to work with the Vertex EVX-R70 repeaters (and it's cousin the Motorola XPR8400). There's probably some online instructions out there on Repeater-Builder or similar sites. I'd peg it as a project for intermediate with skills to advanced/experienced. The inexpensive way for someone with experience would be to buy a good used tone panel (I've seen used Trident Raider panels go for less than $50 with free shipping on eBay) and find some online pinouts for crafting your own cable. You would also need some equipment to set deviation levels and repeat audio, and you would need to reprogram the repeater to function as a base with an external control panel. Without knowing your skill set, patience, and equipment - it's kind of hard to give a recommendation. Trading out your repeater for another unit that already has a Multi-tone function built in (Kenwood TKR) might be an option.

You can certainly use an external controller & set it up like a community repeater with multiple PL or Tone groups. If that's what you want, there are other Repeater options out there with that feature built in, but a $75 or $100 used external controller will do the job. I doubt you would want to manually switch tone groups.

There are ways to do channel steering through the rear accessory connector - and programming the GPIO pins, but I don't think I've ever seen anyone doing it on the lower end repeaters. As you discovered, there is no real reason to do anything more than 1 channel for most of us. Other than that, it's just legacy from the original mobile radios that are inside the box - and someone decided that advertising a 16 channel repeater was more impressive than just a single channel.

I remember hearing an old timer story about the one time they got fined from the FCC - because they had a Part 22 transmitter that was BELOW the wattage specified on the license. The FCC had warned them, and they didn't take it seriously because... well, nobody ever heard of a fine for being below your allowed power. That story came about because we were brainstorming around at a dinner meeting during the early days of narrowbanding and refarming, and some of us saw the same opportunity for more available talkpaths in Part 22 if you did some creative channel splitting and re-use of offset frequencies. The old timer warned us that in Part 22, things didn't need to make sense but you did need to follow the letter of the law. Again, that was 20+ years ago and a different era with the FCC and enforcement actions.

During that FCC Auction 20+ years ago, I attended an FCC Seminar down in DC & got to sit in with a bunch of people talking with FCC staff attorneys regarding the Auction process. One of the things we learned was that the FCC was only allowed to auction spectrum if there was more than one competing application for the allocation. That was the reason the attorneys always suggested that people checked the "all" button on their application, as they wanted to make sure that every market had a potential competing application. You did not need to bid on all the markets you expressed interest in, but without a competing application, the auction process could not legally proceed. Not sure if it still works that way, or if the FCC convinced the legislature to amend the auction rules. You would think that the concept should be to put the spectrum to use - rather than to just maximize Federal revenue. Google 1997 PCS auction defaults if you want to read up on some FCC comedy.