Radioguy7268

My biggest issue with digital on GMRS is the lack of interoperability. Different modes don't talk to different modes, and analog users (which would be all FRS users and all existing type-accepted GMRS equipment) will have no hope of ever being able to understand what is being said on a digital system. The only people who'd immediately benefit from a rule change are those who aren't using Part 95 equipment. Most importantly, 95.1731(a), ((1), and (c ) would no longer be effective if stations were no longer able to communicate due to differing modulations.
 
The FCC has already explained why they aren't going to do digital voice on GMRS, and they cite this reasoning:
 
CTCSS/DCS is a flimsy excuse since operators using tone squelch can easily disable it to monitor for other traffic, and users with priority traffic can transmit with tone squelch. Even if they have to do it on a split-tone repeater's output frequency, there's still the chance that they'll be heard. Commercial digital radios are designed to mute traffic sent to other destinations (for example, private calls on DMR), so traffic addressing becomes a factor and impedes the capabilities of listen-before-talk. Promiscuous mode is not a standard feature.
 
Dual certification is more difficult after 6.25-equivalent narrowbanding requirements began to get implemented in Part 90, since the radio would be capable of transmitting a non-compliant emission designator or scrambled/encrypted traffic on GMRS channels. A set of significant changes to the programming software could resolve the issue, but that's additional costs and confusion for us and less planned obsolescence for the radio manufacturers. It's not impossible for a 6.25e radio to get dual certification since there's no requirement to prevent users from programming digital channels onto GMRS channels, but it's a big can of worms for the FCC and extra costs for the manufacturer.
 
If I had to pick a mode, and if licensing/equipment costs were assumed to be negligible, I would endorse P25 Phase 1. It's theoretically vendor-neutral, easy to modulate, better suited on simplex operation (NAC of F7E and non-talkgroup operation), and most of the equipment already out there already has mixed-mode capability. Unfortunately, we can't trust everyone to properly program their radios for mixed-mode operation and listen-before-talk.
 
GMRS isn't the place to set up commercial-type repeater systems, it's a place for travelers and family members to talk to each other. That's why we have the amateur bands.

Update:  Thanks to @Radioguy7268 my first VX-264 is on the air in wide-band mode.
 
Some notes for those who may follow...
My Vertex Standard branded VX-264 with firmware 2.07 just arrived today and I used the Motorola CS150 v5.01 international version software to program it.
 
To switch the radio to accept wide-band channel settings I used the Wide_Band_Recovery_Tool software v1.03. (This is not available from Motorola but, thanks to Radioguy7268, I can share a copy with anyone who needs it.)  NOTE: with the VX-261/264 radios you must use v1.03,  v1.02 does not support them.
 
I did not use, though I have ordered one, the FIF-12 programming adapter. Instead, I used the <$20 CT-106p cable from BlueMax49ers. 
 
Extras: I do not own any windows machines so I used a Win-7 VM in VirtualBox for the wide-band recovery and programming. Also, as my MacBook only has USB-C ports, I used a USB-A to USB-C adapter.
 
So far I am very pleased with the radio and find it almost ideal suited for CERT type applications.

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.

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'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.

You can't use analog RF linking on GMRS. There's nowhere to put the links anyways. Use point-to-point Wi-Fi for building networks. If the repeater's receive side is solid in all desired locations, try improving the repeater's sensitivity with more robust filtering and a LNA before trying to figure out where you're going to put a bunch of voting receivers. Simulcasting would be overkill.
 
RTCMs don't take a 10 MHz clock directly, they require some PLL device to shift the frequency down to 9.6 MHz. There's plans to build such a device that are readily available, but there isn't an off-the-shelf solution. A 9.6 MHz OCXO would work for voting purposes as well. All of this is far more complicated than improving the repeater's receiver, since it turns a standard duplex repeater into a computer-controlled radio network.

Wideband has a slight advantage (3dB) over narrowband when it comes to sensitivity. Cutting the bandwidth in half requires 6dB more power to get the same signal-to-noise ratio, but 3dB comes from having the noise power on the narrower receive IF filter. On business radio systems, this may not matter; but on GMRS, the users tend to be dispersed further as operating area isn't constrained by the license and minimal frequency coordination takes place. This effect also causes mobile flutter to be more pronounced. On modern commercial radios designed for narrowband use, the strong-signal voice quality doesn't take much of a hit when moving to narrowband channels.
 
We can't get any more pairs because FRS is already authorized for the 467 MHz interstitials. We'd need to go to 6.25 kHz ultra-narrowbanding (NXDN48 or dPMR) and use some odd channels (462.546875, 462.553125, 462.559375, ...), which won't happen anyways because digital voice isn't allowed. Adjacent ultra-narrowband channels would also interfere unless frequency accuracy is well-controlled, which raises equipment cost considerably (particularly for portables) and requires realignment during the equipment's service life. Additionally, wideband users would take interference from any of four ultra-narrowband channels, and narrowband users would take interference from any of two ultra-narrowband channels. The end result is even less voice capacity than before, unless everyone goes ultra-narrowband and maintains their equipment to high standards.
 
The repeater operator always has the option to narrowband should they want to, but there's no benefit unless there's significant adjacent-channel interference, all of the radios are properly configured for narrowband (travelers are probably not), and the radios used on the system have proper 12.5 kHz IF filters (the GMRS-V1 does not). A narrowband mandate would also screw up equipment certifications and cause the FCC to get a big headache over something that is not really a problem at all.

You get more fidelity at a given power level using a wider deviation. You need more power (a net change of 3dB in this case) to reproduce a transmitted signal with the same fidelity. So if you've got a receiver trying to receive your buddy down in the valley and you're in a theoretically perfect hilltop site, you'll have -130dBm of thermal noise coming in. If everything is wideband, your buddy needs to be received with some signal-to-noise ratio to achieve some level of fidelity. Let's arbitrarily set that threshold -122dBm to achieve a good-enough signal. If your buddy switches to a narrowband radio and you switch the repeater to a narrowband configuration, you'll have a narrower IF filter and thus less thermal noise within the IF passband: -133dBm. Passing the input signal at the same signal-to-noise ratio (which would be received at -125dBm) will not reproduce the input signal at the same degree of fidelity -- it'll sound worse. You're trying to do the same thing with less RF, it just doesn't work like that, or we'd have been 6.25 kHz compliant for a long time. The signal-to-noise ratio needs to improve by 6dB each time the bandwidth is halved to produce the same fidelity, and we gained 3dB from the narrower IF filter. To get the same fidelity, we'd need a received signal at -118dBm. The easy way out of the problem is to lowpass the audio so less noise is audible, and that's one of the reasons you'll hear a lot of people say narrowband sounds like junk. The audio loses fidelity in the process, but has less high-pitched hiss from FM noise.
 
The problem is with reproducing the transmitted frequency range. More and more RF power is needed to allow the higher pitches to be demodulated with an audio SNR above a fixed threshold as IF bandwidth goes down. It's a property of FM.

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.

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.

You posted a request about help selecting a radio, to which I responded. If you don't want to hear what other people have to say, don't post. My point was, if you are willing to consider Part 90 radios, there are a lot to choose from.
 
If you don't want an M1225, the CDM1550 is newer and there are a lot of them on eBay. They will outperform a cheap CCR (and the Midlands are exactly that at inside) long after the CCRs have died.  However, if you don't like Motorola, try Kenwood. They are solid radios and easier to get software for. Just search the forum, there are dozens of posts on the Kenwood radios.
 
But, suit yourself.

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.

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.

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.

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.

Back to the original post:
"50' RG8x cable"
 
That is the first thing to lose for better results.  50' of RG8x has over 4dB of loss at 465MHz. Replace it with LMR-400, and you will reduce loss to around 1dB. That extra 3dB hitting the antenna will literally DOUBLE your transmit power at the antenna. Receive sensitivity will increase dramatically as well.
 
RG8x is just not the right cable to use at UHF frequencies, unless you are running it less than 10'.
 
RG8x was originally designed as a thinner alternative to RG8u for running under carpet in HF or CB mobile installations that required less loss, or higher power handling, than RG58u, the typical mobile cable. RG58u and RG8x were never intended to be used in 50 foot runs, or on base stations, in the first place.

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.

Something to bookmark on your browser. The Enforcement Bureau has opened a new portal to report interference and complaints for Public Safety, Business users and consumers. GMRS/FRS users can report problems using the Consumer tab at https://fccprod.service-now.com/psix-esix/

Andrew LDF7-50 was replaced by Andrew/ComScope AVA7-50.  1-5/8 line.
 
At only 225 feet, you might be just as well off with a less expensive, and much lighter weight AVA5-50 7/8 inch line.

If you're on flat land, such as near the ocean like you, then yes, a 5/8 wave antenna will give you a natural 3 dBD of gain over a quarter wave.  However, in hilly terrain, or in the mountains, particularly on UHF, this is NOT a benefit, and a quarter wave antenna will give you much better omni-directionality "on the tilt', which is preferred over forward gain in these areas.  There are discussions elsewhere on this site about this matter.

I am currently running a Tram-Browning 1485. 5/8 over 1/2 wavelength with ground-planes. Cheap. Tune-able. DC Grounded element. Fiberglass radome.  5dBD gain.  Just under 4 feet tall.  Works well.
 
I still prefer quarter-wave antennas for mobile use.

The user programming software can be used to unlock the frequency range. At least it does on the Amateur version of the radio. Mine came locked to the Amateur Bands only out of the box.
 
Click on the "Frequency Range" tab on the left side of the TH-8600 programming software.  You should then see a small window with 3 frequency ranges on the left side, 150M 250M 450M. If you click in any of the ranges to the right you can't change the settings. Now press the "P" key on the computer keyboard. This NOT documented anywhere. Now you should get a small edit box that opens on the bottom of the frequency range window to enter a code. Type in "8600TH" without the quotes and is case sensitive. Then click "Enter". You should be able to click in any of the frequency range boxes now and change the values. Next write the code plug to the radio. Once this was done on mine I've never had to go back and change it.
 
I can't say if this will work for the GMRS version of the radio but if somebody has one and wants to try it then let us know.

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. 

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.