Radioguy7268

A UHF Phantom antenna is NOT 3-5 dB gain. At best, it's a zero gain. You'll see them advertised as a 2.5 gain dBi (Gain over an isotropic) - which is Zero dB gain. Some people decide that 2.5 dBi rounds up to 3 dBi for advertising purposes, and since most people don't know or care to figure out what the difference is - it means that dBi ratings sell more antennas. If you want a true Gain antenna in UHF, you're going to need something taller than 1/4 wavelength. That said, the Phantom antennas are decent enough for what they are, but don't expect any miracles.

IMHO - you don't have an antenna problem. You've got a radio problem. 3.5 miles with 40 watts in relatively flat terrain in mid Ohio is not a line of sight problem. Those Midlands are quite honestly garbage. You are going to spend a lot of time (and money) trying to make those units perform like actual radios should. Go buy some used Kenwood/Motorola/Vertex radios programmed to GMRS (which will end up costing half as much and work three times better).

The only company that I know of which still offers a "standalone" GPS for analog emissions is IDA company - www.idaco.com The stuff works, but it's not a 'cheap' solution. I'd also tell you that if you're heading in that direction - why limit yourself to MURS? Get a real part 90 license & go for something with some legs. No sense spending for a self contained GPS solution that's only good for a mile or two, and have to deal with trying to integrate it with MURS limited equipment (your EVX radios are still not MURS legal if you're running something with a detachable external antenna - which you'd pretty much need in order to throttle it down to 2 watts.) There used to be a few companies that made a WiFi based GPS solution, where the vehicle would have a GPS antenna & receiver that would collect tracking information throughout the day, and whenever the vehicle returned within the range of the Home Base/Transport Garage - the WiFi would connect & download that day's info. Not exactly real time, but it did the trick for History Logging. It would also work within a few hundred foot radius if you got the WiFi access point up high enough. Not sure if you could make something like that into a real-time tracking setup, or if there's anyone still making that. I haven't seen anyone trying to re-sell any old turn-key systems via Ebay or anything. There's a few units offered for sale that plug directly into a vehicle's OBD-II port & work through Cellular data at a fairly low monthly cost.

I'll toss in the dissenting opinion. There's absolutely nothing wrong with a DB404 dipole. Proven design with good spec's. It's probably overkill for a home "base antenna". Especially if it's being mounted at the top of a 40 foot unsupported and un-specified "pole". I'd be concerned about ANY 40 ft. pole for a home antenna. I'm also thinking that a base antenna in GMRS is mostly going to be used to control a distant repeater. If so, the repeater's location and antenna situation is more important than the base radio's antenna. Use any decent 5 or 6 dB gain omni fiberglass antenna, and quality coax, and you'll hit 90% of the repeaters that you'd ever get with a DB404. You'll also save yourself a few trips outside during the ice and snow to see if your 40 foot pole is still standing vertical. You will probably save a few hundred dollars also.

Avoid ANY Chinese mobile that you find advertised for GMRS. You can't even call them Cheap Chinese Radios - as most of them approach or exceed the cost of real Commercial/Industrial radios. Action Communications in Arizona has the VX-2200 UHF for under $300 on eBay and their website, and if you call them, they might be able to tell you what they would do for programming. Buying new in this case is good, as you'll get all the power cables, brackets, and accessories that you'll need, but I would not be the least concerned about buying used Commercial equipment from a reputable seller. Mobile units often last 20+ years in daily use conditions, and the few parts that wear out (microphones and cords mainly) are easily replaced.

VX-2200's are nice little radios. Only "weak spot" I've ever noticed was the palm mic (cords would fray). Audio was good at 25 kHz. If you get a "Motorola VX-2200" it's going to be locked to 12.5 Narrowband, and you'll need to go through some steps to "unlock" the Wideband feature. You'll also find that the Motorola version of the Software is a little harder to come by. Vertex Standard previously made/sold the VX-2200, but Vertex got bought up by Motorola, and now in their infinite wisdom, Motorola has cancelled the VX-2200. Some online sellers still have quanties of new units that they're selling. If you can find a seller who is willing to program them at 25 Khz "Wideband" right from the start, I wouldn't hesitate to grab one. If you never programmed a radio before, trying to unlock a new unit for Wideband might be a little daunting, but it's not impossible. Good luck with it.

Better take a look at the FCC Certification. Less than 3/4 of a watt certification for GMRS. That's usually a sign that it was throwing off spurs at higher power levels. There's a reason all those CCR's are showing oddball power & emission certifications for Type Acceptance. It's not because of translation errors IMHO.

Not entirely true. Your transmit coverage will always look better when you model a higher elevation, even at lower power... BUT... at some point, the repeater is just part of a System, and any repeater system that does not receive as well as it transmits, is mostly a one-way paging transmitter. If you want the mobile/portable users to talk back in, then having a clear and clean receive frequency matters, and having a well tuned receiver matters. If I stick your receive antenna high in the sky, the good news is that you might hear transmitters 100 miles away. The bad news is, you're going to hear stuff 100 miles away that wasn't part of your system, and if those transmitters interfere with your ability to receive desired transmissions, then you're back to having a deaf System.

for the OP - I believe that an M208 can be programmed using the generic Radius M100 CPS. I believe "RADMBL" is the keyword to search on & find the program at HamFiles. The GR300 was a nice & simple design, but we called them "hot boxes" due to the heat issues that killed high power applications. Keep it as a 10 watt & under repeater with clean, cool air flowing, and they worked well. I'd be concerned about trying to run it as a 40 watt repeater with anything more than a 5 or 10% duty cycle.

MURS would be VHF and Since the Talkabout Distance should be an SP10/SP21 in disguise, they should work with a standard Motorola NAD-6502 helical antenna - provided the antennas are actually screwed in. Something tells me that the earliest Talkabout Distance models were, but later on, all MURS designated units no longer had a removable antenna. I believe that Spirit was a similar form factor - just a different name. If so, they should also work with the NAD-6502.

I'll just point out that if anyone wants to do UHF DMR, the FCC already allows for that. It's called Part 90 Private Carrier (FB6 designation). Go get a 10-year license - get a Coordinated Frequency pair, and have at it. You no longer need to be concerned about getting Part 95 certified equipment, you don't need to worry about who qualifies as a "Family" member, and you can go ahead and "rent" airtime to anyone you want to, at any price you choose to. There's no requirement to charge a set amount or fee to anyone as a Private Carrier - you get to set your own rates (Zero if you wish), and you get to decide who uses your system. In 10 years' time, DMR will probably be the defacto standard for UHF/VHF conventional systems, but the FCC is slow to recognize trends when it comes to their standards of "interoperability". I think you'll spend a bunch of time herding cats & trying to get everyone to agree on the same type of Digital modulation scheme if you try to get the FCC to make a formal rule change for Part 95 GMRS.

How many elements does your Yagi have? Do you know the dB rating? Most of the time a UHF Yagi would have 3 or 5 elements. More elements would usually equal more gain, but also give a tighter beam or higher directionality to the antenna. Do you know for sure the compass heading to the repeater(s) you are trying to reach? Your feedline is minimal (rated 6.5 dB of loss / 100 ft. at 450 MHz) but a 15 ft. section shouldn't be killing you, provided the connections are proper.

I'd say you're on the right path, but if they are brand new units, you are 99.999% guaranteed that they're going to be locked to Narrowband. If they're just some used units that are Vertex branded with older firmware, the Wideband Recovery tool should be the ticket. Motorola will tell you that you need to buy the FIF-12 tool for updating. No ifs, ands, or buts. I have updated older units using their Wideband Recovery tool and a simple USB cable. I have not had that same success on newer EVX radios that were MSI branded. I've read the same info about a mystery version 1.03 that isn't available through the MOL site, but I haven't bothered to call Motorola to see about getting it directly. Good luck with it.

The only potential GMRS trouble I've seen with the Motorola branded EVX-S24 and EVX-261 is getting them to work in Wideband. The Motorola units I've gotten in are strapped as Narrowband out of the Box, and I've yet to be successful in changing them over to Wideband. I've done that with ease on Vertex labeled units, but there's something that I haven't bothered to figure out when it comes to the MSI branded version. I've heard people say that you NEED to use the FIF-12 cable in order to use the Wideband enablement mode (as well as using the Export version of software) - but I haven't bothered to try that out, as my basic Vertex cable worked for updating (backdating?) previous Vertex units to Wideband enablement. They do seem to be great little units for the price. Be aware that the EVX-S24 is only listed at 2 watts for Analog UHF (3 watts DMR). *Edit - just noticed that you specifically said the VX-261. Same issues may apply, but the analog VX-261 is a screaming steal in the Used market. I've been snatching them up in good condition at less than $40 per unit with accessories.

I'll point out that I've got a customer running M1225's in Concrete Mixers. They've been on the air with this system since 1998, so 21 years & counting. They've had a few failures along the way, but it's mostly been related to some driver dumping a fresh cup of coffee into the radio, rather than a failure of design. Yeah, after 20 years, they don't look all that pretty, but they sure do work. If you want something more "modern" - you can take a look at the CM300/PM400 which also has a pretty good reliability record. If you don't want to invest in the programming software & cables required, you can always just figure on an extra $25 to $35 in "sunk" costs to have them programmed. Many sellers will include basic programming for a few channels in the cost of the radio. Don't expect to get 250 channels programmed for free, but if you're in that mode, you would definitely be better off to roll your own programming. I'd still rather spend $100 to $150 on a used Motorola or Kenwood radio built to last, than a Midland radio brand new. That's just my opinion.

Let me just throw in that even if you're using Part 90 equipment under GMRS, there's nobody making a case that DMR digital operation is legal within the GMRS band. I'm on the side of people who believe that the FCC is aware & acknowledges that people are using Part 90 equipment, and they've done nothing to discourage the use.

It could be a programming issue, or it could be a "privacy" issue. Most of the CCR "radios on a chip" don't have all the extras that Motorola puts into their radios, like Basic or Enhanced Privacy. If the Police have certain departments or talkgroups that are using the Privacy function, you would have trouble picking up those transmissions in the clear. You could also be experiencing a CCR moment, where for no good reason, the radio just decides to stop decoding. If turning the radio off, and turning it back on during one of those missing conversations, gets you decoding the same DMR datastream, you can pretty much blame your radio firmware. I can also tell you that the receive selectivity on most of the CCR radios is nowhere near what most commercial Part 90 radios from Kenwood or Motorola would give you. In other words, expect that the CCR will stop receiving as soon as another decently strong transmitting unit on any nearby frequency keys up. That could be another portable in your immediate vicinity, or a high powered base radio even a half mile away.

Any desense is too much. I've run plenty of 4 cavity duplexers in the scenario you describe (adding a bandpass cavity to the receive side) with absolutely no measured desense at 50 watts. If you can hear desense, you're probably seeing at least 2dB of loss in the receive path. 2 dB doesn't sound like much, until you realize that 3dB better of receive sensitivity would double the coverage area of your system's portable talk in. I guess it's human nature, but people will always pick the 4 watt portable over the 2 watt, yet how many of them will spend the time & money to improve the receive side of their repeater to gain 3dB? The net effect is the same. Getting 3dB of receive improvement will make your 4 watt portable seem like it's suddenly putting out 8 watts.

I'd look at why your repeater doesn't receive as well as it should. If it can transmit out with full quieting to 15 miles at just 7 watts, then a 4 watt portable should talk back in from that distance. A good used band pass filter & a receive pre-amp would set you back less than $250. What's your effective receive sensitivity measured at the site? (how strong of a signal does your receiver system require before it opens the repeat audio path?) What's the noise floor? Do you have any desense when the repeater begins to transmit? Your idea of satellite receivers is worthwhile, but you're already seeing that it's limited due to the lack of frequency spacing and spectrum if you stick to GMRS.

I think there's confusion between an RF ground plane, and electrical grounding. For UHF/GMRS frequencies, a ground plane is required for best signal propagation when you're working with a 1/4 wave antenna. A longer 1/2 wave antenna does not normally require a ground plane. The ground plane is a counterpoise to the antenna's radiating element. The counterpoise (RF ground plane) is going to reflect signals that would otherwise be radiated down by the antenna. For plastic body vehicles - look for something like this to use as an RF ground plane: https://www.solidsignal.com/pview.asp?p=K332 - or just use a 1/2 wave antenna. The DC ground for a vehicular antenna is provided by the coaxial shielding braid. That's going to measure continuity to vehicle ground no matter what type of plastic you're mounting the antenna to... provided the radio chassis itself is actually grounded. I realize I'm being simplistic. That's where we need to start from when someone wants to "ground" their antenna.

I'll toss in another vote for used Kenwoods. or Motorolas. or Vertex. Used commercial/business radios are a great fit for GMRS if you can handle the programming side of things.

You didn't mention what you wanted to use your "base" antenna for, or how you wanted to mount it. At my house, I've got an inexpensive Ed Fong antenna that costs around $40 off eBay. I've got it strapped to a chimney mount. It's reasonably small & lightweight, the white PVC doesn't stick out in the neighborhood, and it covers both VHF and UHF frequencies - so when I want to hook up a VHF scanner for local fire & township events, it does the job for that also. For GMRS, I'm only using it for a UHF control station at my house, so it doesn't need to be anything special. It just needs to hit my repeater that sits 14 miles away, and it does that reliably and cleanly. I've had it up for 6+ years now, no issues.

I'd rather side mount a 1/4 wave antenna than use one of those hockey pucks up on the roof. I have a tour bus customer who insists on using those low profile hockey pucks because they think that they rip off too many masts, and the drivers won't look up to check if the antenna is still there before they start out on a trip. You know what they complain about now? Range.

Vertex are pretty decent little radios - especially if you get them for free. I haven't played with the EVX-351 itself, but I have programmed a few of the analog VX-351. The EVX series is capable of either analog (legal for GMRS) or DMR digital (not an approved format for GMRS). The more recent versions of Vertex radio software is narrowband only for US users. You need the international version of software if you want wideband capability (Wideband 25 Khz is used on most GMRS repeaters).

If you've already got the existing (and properly tuned) Celwave 6 cavity notch duplexer, I'd improve the situation by just putting a tuned bandpass cavity on the receive side. I've always been leery of running notch duplexers on any type of high power/high performance machine. When you're dealing with isolation figures less than 60 dB, every increase in transmit power is also an increase in noise on the receive side. One of my eye opening experiences in the early days of my radio career was watching an old-time tech turn DOWN the power on a repeater to increase the actual performance of the system. Suddenly, handheld portables on the edge of the system were now getting in cleanly - effectively increasing the usable range of the system. Also, make sure that your jumper cables between the repeater and duplexer are up to the task. I've seen lots of duplexers get blamed for poor performance, when it was really the old, cracked jumpers that were causing all the problems. I have used some of the 8 cavity notch duplexers for on-site repeaters running at 10 watts or less, and I've found them to be a good option. I've also seen a great variation in the tuning ability of different Chinese suppliers for their duplexers. If you're buying one that is supposed to be tuned, you better have a way to verify it.