Radioguy7268

I don't believe that Part 95 properly defines the term "Fixed Station" - which leaves the meaning open to interpretation. To my mind, a Fixed Station operates on the High side of a Frequency Pair - which would be the 467.xxxx frequencies. In other words, they would be transmitting on the repeater inputs -and potentially causing interference if they operated at high power with a high gain directional antenna. Base Stations transmit on the lower side of the Frequency Pair - ie: the 462.xxxx repeater outputs. At least, those are my definitions. The FCC has left us to figure out which ones make sense absent any Part 95 definitions or rulings.

Commercial tower sites tend to be expensive. Most towers are owned by the 3 or 4 major tower players, and they generally deal with cellular and other wireless carriers who will sign 20+ year leases with $1500+ per month. I've heard of premier location tower sites with rents over $4000 per month. Now, a cellular carrier wants premier tower space, and they're hanging massive amounts of equipment (3 or 4 antennas per "sector" - with Remote Radio heads on at least 2 or 3 of those antennas, and 3 sectors for a standard triangular array). You need a footprint that's about 1/10th of what a cellular carrier wants, but the national tower companies don't generally respond to offers of a month to month or annual lease with rents of $150. There's a ton of high rise hotels out on Daytona beach, and I'm sure a few of them have space on the rooftops. Avoid the ones that already have cellular antennas on top, as there's likely a management company involved who is already in control of everything that's going up on the roof. I would try to find one of the less prominent hotels that's still locally owned and operated, and see if you can't work out a deal for rooftop space. You could probably swing a deal for annual rent (paid up front) that wouldn't break the budget, and you also wouldn't need to worry about hiring a tower climbing crew, or paying for 200+ feet of high end Heliax coax cable. Find a maintenance guy at one of those hotels and offer to bring him lunch one day, it might make it easier to get up onto the roof. I'd also tell you that a 50 foot HAAT out on the Florida coast is nothing to sneeze at. You won't cover the entire county, but you should get a good 5 to 10 mile radius without even trying.

Tripod? Use a string & a decent sized rock to hoist your roll up slim Jim up to the highest branch your throwing arm can reach.

MURS is for Multi-Use. Business or Individual, pleasure or purpose. I'd agree that there's no need to run 35 watts (70 watts ERP!) for an on-site system talking back with 4 watt portable radios - but the FCC allows it. I'd also just about guarantee that they're not actually running 35 watts output on the rinky-dink Mall repeater that they're probably using - most small repeaters burn up quickly under a heavy load running that kind of power. 20 watts is probably closer to what's actually being run. I've got Business customers in Construction and Contracting who run MURS radios, mainly because it's quick and easy, with no need to bother trying to license individual site locations. VHF does have a few specific "itinerant" frequencies (151.505 comes to mind) but if you listen in on those channels - you find some of the largest construction firms in the area have camped out on those channels and effectively run off any other co-channel users. They're also using those licensed VHF frequencies with high power mobiles (I've seen more than a few 110 watt Maratracs running Narrowband kits) - so MURS still gives them a place to run a low power portable for job-site use. Quick and easy.

Half the time I see people blaming a "bad duplexer" - it turns out to be the junk cables connecting the repeater to the duplexer. You should be using a good quality double shielded cable like RG400 with the correct ends (no adapters!). Type N is the preferred connector, but if your repeater or duplexer has different connectors, you need to work with those. Try someone like these guys - avoid the cheap "tin" or nickel plated connectors - there's a few USA based sellers with similar products: https://www.ebay.com/itm/6-10-RG400-M17-N-Male-Clamp-Jumper-Silver-coated-RF-cable-USA/131269263466

If the reason that most people get the Midland is because they want an "out of the box, Part 95 legal radio" - then opening up the radio to a 25 kHz bandwidth (which the Midland isn't type accepted for) kind of kills the whole rational they started with. Might as well have gotten something like a part 90 radio that actually did 25 kHz right from the start, and saved the time & trouble. It would be just as legal (maybe more), half the price, and work twice as well.

Back in the late 90's - Kenwood offered ( I never actually sold one, but saw a few units being demo'd) a radio that transmitted pictures via UHF frequencies. I believe it was one like this: http://www.acicommpact.com/kenwood/kvt10.html I remember that it was fairly slow data speeds for transferring a low resolution picture - but I can't remember exactly how slow it was. I do remember making a comment during the presentation that I could probably snap a Polaroid & walk it over to the intended recipient before the Kenwood camera would have made half it's transfer - and not tie up the channel during the whole picture transmission. But yeah, in today's world, it seems every phone has a camera, and plenty of the lower end CCR's have options like a flashlight and an FM radio receiver built into them. If you had the ability to transfer picture/video over WiFi it might serve some purpose.

While the information above is useful - there is no correct answer to whether the FCC considers GMRS to be wideband or narrowband. The FCC simply does not care which bandwidth you use, either one is acceptable to them. Most high profile repeater systems do use wideband - for the increased performance noted above. There are valid reasons why people might want to use narrowband, mainly due to available equipment or interference.

I'd be concerned with anyone who let a repeater go out the door & didn't check the duplexer the first time. If he didn't get it right then, what's the chances he's going to get it right this time? It sounds like you bought it from the seller as a working package. Before you send it back - make sure you've got the cables hooked up correctly - the High side should be to the Receiver, low side for the Transmit. I've seen too many jumpers crossed up not to ask.

Sounds like you're in a good position to move forward. It's definitely worth it to get that DB4076 tuned up to your frequencies, and just add a tuned bandpass cavity to the receive side - effectively giving you 3 cans on the receive side, which should get you something north of 85dB for isolation and tamp down any noise before heading into the Preamp. I like the Advanced Receiver Research P460VDG GaAs-FET pre-amp for a budget conscious GMRS build. The specs are great, and the price isn't bad. Make sure you get the unit that covers the 460 MHz band. Noise floor is below 1dB - and effective gain is +12dB. You might even need to pad that down a little depending on your repeater's own internals. I've never messed with any of the Icom series of Repeaters, so no idea how good that FR-4000 is. I'll just about guarantee you that a "hot" pre-amp with 20dB or more gain will overload the repeater's front end. I've heard of some guys liking the Mini-Circuits pre-amps for amateur stuff - but the advertised noise floor of 2.5 dB scares me off. I've never actually had one on the bench to try it out. Maybe someone else here has. The best pre-amps I ever touched were made by Angle Linear - but apparently they closed up shop around 2017 or so. Sinclair used to use the Angle Linear inside all of their high end Multicouplers - which I took as pretty high praise, since apparently Sinclair didn't think they could make one on their own any better. Lightning is the #1 killer of pre-amps. Make sure you're bonded and grounded. Read up on Motorola's R56 standards if you haven't studied them before. Good luck with it.

Receiver pre-amps are NOT magic. In many cases, they'll actually make a system worse. Signal needs to be greater than noise. The benefit of a pre-amp is in raising the strength of the desired signal above the noise floor. If you raise the noise floor at the same time that you're raising the signal, you've done nothing to improve the Signal to Noise ratio. You need to have proper front end filtering in place before you even consider a pre-amp. If you're using a 'flat pack' compact mobile duplexer, you're not doing yourself any good to add a pre-amp. If you've already spent the money to hang a quality antenna that's up above the tree line, and you're running a high quality bandpass/band reject duplexer, you might see some improvement by adding a pre-amp. Might. We have no idea what your system is currently, or how it's performing. Do you have the tools and knowledge to measure receive sensitivity of your repeater? Do you have the tools and knowledge to measure de-sense?

Motorola MOL dealer website still shows them as being available - Dealer cost is north of $150. Adding on a 15-25% nut for profit margin, plus shipping, and you're probably going to pay @ $200 or more. I don't see any of them currently available on Ebay. Are you looking to buy new? Or hoping to find someone giving one away?

Again - Part 90 is NOT controlled by any of the amateur Frequency Coordinators. You're going to have to check with someone else. There are certain particulars that involve areas of operation that get within a certain distance of the Canadian borders. I'm not up in that area, so I've never really paid much attention to the Border rules.

I'm not sure how close you are to Canada - but just wanted to make sure I'm clear. Business frequencies under Part 90 do not share any frequencies with amateur radio. Your comment about 440 and 222 makes me wonder if you checked availability with an amateur Frequency Coordinator. There is no "waiting list" in the Business bands for Part 90 UHF.

I think you've got the concept - run under Part 90 as an FB6/IG - but you need to certify that you're going to provide communications service to "Part 90 eligibles" - which means US Citizens and US Companies that would be otherwise eligible under Part 90. Technically - you could also provide FB6 Private Carrier service to Public Safety entities - or a non-profit Town Watch group. I'm not the law, and I'm not the FCC, but I've done this type of licensing for other entities. You are the one who needs to certify what you are planning to do, but I'm not aware of any requirement to "show your books" to the FCC to prove that you're running a for-profit business, or any site inspections. You will need to run Part 90 type accepted equipment, and you will need to certify buildout/construction within 1 year of your License being granted by the FCC. Judging by your GMRS license, you're located in a fairly populated area, so finding a decently clear frequency pair might be a bit of a challenge in the Part 90 spectrum. If you've already got a 60 foot mast, try to monitor some frequencies and see if you can identify any open frequency pairs in the area. Used to be that some of the older 451.8xxx pairs were clean, but most communications companies have snatched those up - at least in my area. I'd try looking up someone like FIT (Forest Industries Telecommunications) or EWA (Enterprise Wireless Assocation). They'll walk you through the steps. I find FIT to be a little more personable - but EWA is very professional & capable. Up front cost isn't cheap to get the 10 year FB6 license & coordination - expect to see something around $700, but it's still pennies per day. If you tell them you're looking for an FB6 UHF repeater pair with DMR/Trbo emissions, you'll be off to the races.

I've currently got 45 P1225's (mix of 2ch & 16ch) and over 20 CP200's in my rental fleet. Then there's the mix of 36 VHF and 36 UHF Vertex VX & EVX portables - not to mention all the Trbo DMR radios. I think I'm set. Some folks think I'm just sick.

That's a pretty good price on the CP200's - especially for working units in decent shape - with the charger. You might also mention that the P1225's are Part95 type accepted - one of the few Motorola portable radios available for "legal" GMRS use.

12 miles from a repeater with a J-pole should not be a problem. I think you'll be fine.

The "e" series is great. There's a ton of audio enhancements & profiles that will keep you busy trying to figure out which ones sound best. The good news is that for Analog GMRS, all that doesn't matter much if you use AGC (Automatic Gain Control). There is a member here who uses an XPR5500 with a remote hand held control head/palm mic. It's a high end radio, but it delivers high end results. Don't forget to load the "Voice Announcement" files into the radio and then set up the voice profiles. There was an issue with the older XPR5500 non-"e" models, where you could not fit in all the factory default voice files, but once you deleted a few hundred un-necessary channel and zone files, it would load up fine. Programming is difficult until you get the hang of it, but the good news is that Analog programming for GMRS is a much easier path to success. The wideband entitlement is a little bit of an adventure the first time through, but once you understand that you're loading the EID, then registering/verifying the EID key with Motorola's server before you can actually activate the feature, it goes a little easier.

I'd tell you that an "inexpensive amplifier" is really just a broadband noise generator. Yes, your meter might now read 50 watts - but it won't show you that you're not only putting 50 watts out on your desired frequency - you're also putting out some unknown amount of spurious energy out on adjacent frequencies (and multiples of your frequencies) - potentially interfering with other systems. Worse yet, those cheap amplifiers put out enough spurious noise that it will probably interfere with your own receiver - making that alligator system even worse. You might find some used TPL or Henry amplifiers in the less than $200 range. There used to be a ton of Motorola vehicular repeater amps being sold on eBay that would do 40 watts - but most of them were VHF. I'd be very wary of using any amplifier with a CCR radio. There's 100 ways to make your system talk better, and 98 of them don't involve an Amp.

The specs look pretty decent. I have not seen that brand before, but it appears that he's got pretty good reviews on Ebay from his buyers - with a 100% feedback rating. The only negative comments seem to regard the shipping from Canada taking too long. 80dB of isolation is more than acceptable from a 4 can duplexer. Rule of thumb is 30dB per can (per side), but I can see that there are what appears to be some trimmer capacitors - which will sharpen the notches & help isolation. Generally, those are a good thing, but the quality with which the trimmers are built will ultimately decide the useful lifespan of the duplexer. See: http://www.duplexerrepair.com/2016/12/26/trimmer-capacitor-failures-in-decibel-products-duplexers/ It appears from the pictures & pricing that they're trying to strike a reasonable balance between quality and price, and they're shooting for the ham and hobby market - and at that price, they should have pretty good response if the quality holds up. Assuming you're going to use it as a lower power repeater duplexer, it looks like it should perform well.

Yes, the repeater will be transmitting on the 462.xxx frequency - and that's what your mobile radio will be listening to.

I believe I got a notice from Kenwood a few months back saying that the TK-3170 was going to be discontinued. I'm sure there's a few still sitting brand new in Dealer inventories. If you're looking for the TK-3170 K4 full keypad models - I've got 3 currently in stock. Nearly new, but not. Make me an offer.

Nothing stops anyone today from running Narrowband in GMRS. If the repeater owner thinks that setting the receive window to 12.5 Kc will improve the receiver performance for their particular situation, they can do it. Most repeater owners run 25 Kc wideband because it works better and sounds better. The day that 12.5 becomes the better alternative is the day most will switch. In most parts of the country there is ZERO issue with channel congestion in GMRS. I'll keep mentioning this until folks get it. If you want to run DMR, there's nothing stopping you except for a Part 90 license. Go get yourself coordinated for a Private Carrier license for DMR, and invite all your friends and family to join in. You'll be talking Digital in no time.

I used to work with a guy who had no less than 8 mobiles in his personal vehicle. He had pulled the passenger side seat so that he could install a homemade "console" that also held his Laptop and 3 radios, along with his converta-com amp. He also carried at least 3 portables with him most days. I remember asking him one time how many radios he could talk on at once. I also remember that AAA cancelled his membership because he requested too many jump starts. Some people can take anything too far.