Lscott

Well thanks for the compliments, but the same goes for many others who post on the forums too. There is a lot of experience and technical know how by many others here as you will find out in time. All the commercial radios I posted about have removable antennas. They use the exact same reverse SMA antenna connectors on many of the Chinese radios. The same two-pin stereo type microphone-speaker connections for these radios are also the same as the cheap Chinese radios, AKA" CCR's" here, so the programming cables and many of the accessories will work on both. It's very beneficial to have an antenna you can remove. That leaves the owner the option to use a much better antenna on the radio, or use a vehicle mounted one, some even use the radio indoors as a base station with a roof mounted antenna. The so-called "rubber duck" antennas the radios normally come with are just barely adequate for short range communications. Many people buy a better aftermarket antenna. You'll find a lot of recommends on the forums for various models. I'm guessing why this is the case is when the Chinese decided to get into the two way radio market they needed a "standard" for the interface and antenna connection, so they just copied what Kenwood did.

This is a cut and paste from another post I made. You can find these radios for sale on several auction sites. All the ones I got have been from eBay sellers. You can expect to pay anywhere from $50 to $150 or so depending on the model, radio's condition and accessories included. All pf the radios below are FCC certified for GMRS. Some people like to try and use Chirp for radio programming. While free it may not support all of the features offered by the radio. In some cases its just plain buggy. That's why its far better to use the manufactures software where possible for the commercial radios at least. --------------------------------------------------------------------------- Some of the older used commercial radios are FCC Type 95A certified, which was under the old rules. Those radios continue to retain their type certification under the new rules and are legal to use on GMRS. If you shop carefully and wait you can get some good deals. The programming cables are cheap, and the software, don't use Chirp, are easy to find on line usually for a free download with install key. Personally I have used the following Kenwood hand held models: TK-370G-1 TK-3170 TK-3140 (waiting on slow USPS mail for this one to arrive) The commercial radios have a major advantage over the cheap sub $100 Chinese radios, the receiver sections are far better. As most people tend to discover when in a range fringe area the antenna and the receiver sensitivity and selectivity makes all the difference. https://www.ameradio...ood_TK-370G.pdf https://pdfs.kenwood...170Brochure.pdf https://www.radiocom...40_brochure.pdf Beware the radios come in several different "band splits" denoted by a model type or suffix number. Look at the brochures in the above links and scroll down to the last page. It's usually list under "General" in the detailed specifications. I don't have a commercial mobile radios so I can't really speak about those.

Well this should be good news when the fee is officially lowered. I have a friend that is part of an off road Jeep group and they want to switch to either Ham or GMRS just for their own group. I understand that the national group has moved to GMRS, so this should be welcomed news to them. https://jeepjamboreeusa.com/cb-replaced-by-frs-gmrs-two-way-radios/

Some of the older used commercial radios are FCC Type 95A certified, which was under the old rules. Those radios continue to retain their type certification under the new rules and are legal to use on GMRS. If you shop carefully and wait you can get some good deals. The programming cables are cheap, and the software, don't use Chirp, are easy to find on line usually for a free download with install key. Personally I have used the following Kenwood hand held models: TK-370G-1 TK-3170 TK-3140 (waiting on slow USPS mail for this one to arrive) The commercial radios have a major advantage over the cheap sub $100 Chinese radios, the receiver sections are far better. As most people tend to discover when in a range fringe area the antenna and the receiver sensitivity and selectivity makes all the difference. https://www.ameradio.com/doc/Kenwood_TK-370G.pdf https://pdfs.kenwoodproducts.com/9/TK-2170&3170Brochure.pdf https://www.radiocommunicationsonline.com/wp-content/uploads/2017/10/kenwoodtk3140_brochure.pdf Beware the radios come in several different "band splits" denoted by a model type or suffix number. Look at the brochures in the above links and scroll down to the last page. It's usually list under "General" in the detailed specifications. I don't have a commercial mobile radios so I can't really speak about those.

While this doesn’t have exactly what you’re looking for it is another source of repeater listings. https://www.repeaterbook.com/gmrs/index.php?state_id=none

Merry Christmas.

You’re free to do as you like, same as everyone else here. I just wanted to make a few comments and ask some questions. If you continue with the project perhaps you can give us an update on how it’s working out. I’ve learn over the course of many years there is aways some more to learn, and it doesn’t matter how much “paper” you have hanging on the wall.

Yes tower space is not easy to come by so having access is definitely a positive there. Given the finite resource of only 8 repeater channels how do you propose to to choose who get up there? Having multiple machines on the same frequency, assuming you have a high demand, but using different access codes might be a bit tough. Around the Detroit area where I'm at we have very few machines on GMRS. The one I use is an old fire department repeater on top of a building at 200 feet. Coverage is around a 20 mile radius. There also isn't that much GMRS activity anyway, maybe due to the lack of repeaters. Most of what you hear are FRS radios. Now talk about Ham repeaters, they're like weeds, everywhere, and most see little use. The best one for coverage is this one. http://www.gmarc.org/wp/ I can get into this guy with a 4 watt HT in my family room from 15 miles out. Now that would be a place to stick a GMRS repeater. The repeater my one buddy wants to put up is on the Ham 70cm band. I told him it may not see much use and suggested a GMRS one, nope, wants the Ham band. The sight he has access to, free emergency power - internet - no rent, is on the roof of a two story school. Now this might sound very limited however the location is just about 1000 feet ASL while most everything else around there and out is about 650 feet ASL. The coverage map somebody ran for him, based on the topography, shows good coverage out to 20 to 30 miles except to the north east, likely due to the higher elevation there.

I have a buddy that is in the process of setting up a Kenwood UHF repeater. I also have another buddy who is a professional radio tech for a city transportation department. That guy has to work on everything from the bench to climbing towers etc. yeah so I do some idea. He by the way embarrassed some of the “professional” IT people who couldn’t figure out how to fix the problems with the crappy and overly costly VOIP system using radio links. He told them what the problems were going to be, got ignored, and later proved to be right on the nose. Again do you really need to tie up 4 out of only 8 repeater channels, 2 for you private use? And yes I know about linked systems. There is one I monitored around the Chicago I’ll - Gary IN area during a business trip out that way. https://mwgmrs.com/ While linked systems such as the above exist the primary focus of GMRS is for personal use and local communications. These linked system are starting to look more like a “Ham Lite” type service. If one really wanted cross country comm’s, get a Ham license and take advantage of the well built out D-Star and DMR networks. In fact these networks extend worldwide.

IMHO I would have to question somebody who wants to tie up four out of a total of 8 repeater channels in an area. GMRS is primarily for personal communications, not a business or a public service. This reminds me of crap that happens on the Ham bands. Somebody get a coordinated frequency pair, sometimes several, then sits on them just because they can, or the equipment is long dead and gone but the "owner" won't give it up. Comments about NXDN, well digital voices modes, including for now DMR, D-Star, P25 etc., are not allowed on GMRS. We're stuck with plain old analog FM and the limitations that goes with it.

You might want to have a look at these antennas too. They don’t require a ground plane so you can stick them just about anywhere, even on a plastic roof top. https://cdn.shopify.com/s/files/1/0345/4055/2323/files/bb4302n-whip-antenna-datasheet.pdf?v=1595960075 You want the model(s) that cover 450 to 470 MHz. I would recommend get the one wit a spring in the base for the higher gain models.

Are you sure the replacement antenna is really 4 db? A 1/4 wave on the 33cm band is around 3 inches, more or less, for a portable radio. If it’s really a gain type antenna is would have to be noticeably longer.

I would be VERY careful mounting a tall antenna on an aluminum roof top. Torque from highway speeds hittong the antenna on tree limbs etc. can damage the roof. Even people with a steel roof had sheet metal damage at times. The sheet metal used on many vehicles now days is rather thin. You should consider using some extra bracing under the area where the antenna mount is installed. A few antennas have an optional spring at the base that does a good job of saving your roof top in case of an accidental contact between the antenna and the obstruction. The major advantage to the “ghost” antenna is the very low profile. You can almost forget it’s there as far as pulling in to a garage, parking deck, drive throughs etc. However they are not the best antenna for long range communications. If you have just a few feet of extra coax I would just neatly coil it up and stuff it out of the way. A lot of extra coax you might want to consider cutting it shorter and installing a new connector on the end. Most mounts use RG58 coax which is rather lossy at UHF frequencies.

I don’t believe using a radio in SFR mode requires all radios to be from the same manufacturer. They simply would be required to adhere to the tier 1 and 2 DMR standard. Only the single radio functioning in the SFR mode would be communing with normal DMR radios. With the current rules a conventional analog in-band repeater requires two distinct frequencies, one in the 462.xxx range and the other in the 467.xxx range. So you have two frequencies used to support only one voice channel. Using a SFR one could operate two repeaters, one on a 462.xxx frequency and the other on a 467.xxx frequency. You now have doubled the number of repeaters without consuming additional spectrum. On simplex a number of radios can use what is referred to a Dual Slot Direct Mode. Apparently there are radios that will sync to each other using only one time slot without the requirements of a repeater to supply the time slot sync. What this does allows two such radios to use a single simplex frequency using just one of the two time slots. Another two radios on the same frequency could use the other time slot thus doubling the number of effective voice channels, again without consuming addition spectrum. https://blog.retevis.com/index.php/whats-dual-capacity-direct-mode-dcdm/ https://www.kenwood.com/usa/com/lmr/tk-d240v_d340u/

What would intrigues me about DMR are some of the radios that will function in SFR, single frequency repeater, mode. Of course you have to find one that works. Anyway the attraction is no requirement for using any kind of "cavity" filters which would be necessary on a more traditional in-band system. This means almost anybody could setup a repeater with far less technical expertise required and cost for a decent set of BPBR filters. So until the FCC changes the rules we won't have DMR on GMRS. I do expect that to happen sooner or later, likely much later.

The radio is D-Star, not NXDN. It's also a tri-band with two RX sections. https://www.kenwood.com/usa/com/support/pdf/TH-D74A.pdf The problem with digital radios in general, at least the hand held ones, is they support typically just one digital mode. So if you have an interest in several digital voice modes you're stuck having to carry around several radios, one specific for each mode.

Just a data point here speaking about some Ham HT's. My TH-D74A does multi mode RX from HF up. The scan speed on it is around 20+ channels per second, I've timed it. Its the fastest scanning radio I got. Of course it's not cheap either. About VFO's, yeah I rarely use one. Just about any frequency I'm interested in is programed in one of the memories.

I had a Ham buddy at work that picked up a few of those ultra cheap BF-888S 16 channel UHF "only" radios. Well it he found a code plug hack that would let it work on VHF too. To test it he did a test TX on a Ham 2M frequency in our south building while I monitored it in the north building. Yes it did work. But, this was the big one, I tuned to the third harmonic of the 2M frequency, which put it in the Ham 70cm band. I picked up the signal loud and clear! Needless to say I told him NEVER try to use the radio like that again. The crap coming out of that radio was a interference disaster. But what the heck, it was a cheap "multi-band" radio where you could talk on several bands all at the same time. A real bargain if you get what I mean.

Sounds like you're very well prepared! I think a number of first responders learned from the great north east black out and made better plans. What gets me are the some what frequent posts where a new GMRS user gets a radio for "emergencies" and seems to have no plans beyond that. No idea about how to keep the radios running when the batteries die. Not to mention things like heat, water and food if its really bad. Where I'm at the most likely case is a power outage. For that I have several solar panels, charger controllers and a collection of various sized LiFePO4 battery packs. Some of the radios will operate directly off of a 12VDC supply, others can use a 12VDC power adapter to recharge them. The nominal voltage for a 4S LiFePO4 battery pack is around 13.3 to 13.4 volts over most of the discharge cycle. When the pack is nearly dead the voltage is still up around 12.8 volts. The commercial HT radios I have need to use a charge cradle with a wall wart AC to DC adapter. I modified one charge cradle to add a pigtail with Anderson Power Poles, to interface with the battery packs, since it only needed somewhere between 12 to 15 volts max to work. So when the power fails I can keep the cell phone charged up, radios running and a few lights on using some low voltage LED light strips. I have a gas fireplace I can use for heat and stove for cooking so that shouldn't be a problem. I keep almost nothing in the fridge so I don't worry about that.

When we had the huge north east power black out years ago many people didn't. And those that did had no idea where to go or how far to drive to find gas. I knew of just one service station that had gas, and power for the pumps, and it was reserved for emergency first responders only. Even some of the cops I monitored on the radio where telling their dispatchers they had to walk to their current location, the patrol cars ran out of gas.

I would be rather suspicious of a perfect SWR reading of 1.0:1 across the band. That's something I would expect from a high quality UHF dummy load, and even most of those are not perfect either. I recommend you try another SWR meter. One thing people forget is test equipment will "LIE" to you, and very convincingly too at times! I have to deal with this from time to time since my position working in engineering R and D I have to provide support for our service group. It never ceases to amaze me when a service tech accepts what his test gears says, even when it makes no sense. I have the following in my sig file for my company email. “There are lies, damn lies, and then there is what you see on your scope’s screen.”

This is spec’ed for the Ham Bands only. https://mfjenterprises.com/products/bd-35 For wide band use you will likely be stuck using a mono-band amplifier. Some cheap ones are found here. https://baofengtech.com/product-category/amplifier/ You can use a couple of VHF/UHF diplexers, one on the inputs and one on the outputs, to build effectively a dual band amplifier. https://mfjenterprises.com/products/mfj-916b If you’re worried about drawing too much current from an accessory plug just turn the HT’s power output down to limit the amplifier’s output power and thus the current draw. Oh, the amplifiers are not “linear” since most Ham communications on VHF and UHF along with GMRS/FRS uses FM modulation so the amplifiers are designed for “class - C” operation, which is nothing close to linear. This is done to get higher efficiency. https://www.electronics-tutorials.ws/amplifier/amplifier-classes.html

Thanks for the detailed write up! I’ll have to go over it in more detail later. Out of all the CCR’s you tested which seems to be the best?

I may have mixed up the two . My idea concering the MXTA26 is it might be more sensitive to mounting location compared to other antennas. I noticed this when doing some testing on a Comet CA-2x4SR antenna, also a 5/8 wave gain antenna. The SWR varied depending on the type of mount and how the ground plane was laid out. I tried a couple of magnet mounts on my Jeep along with one home made mount using ground radials bent down at a 45 degree angle on a metal stand in the house. The last one seemed to work the best. In my case I also used the RigExpert analyzer, mine is the AA-1000 model, so I'm familiar with what they can do. https://cometantenna.com/wp-content/uploads/2013/09/CA-2x4SR.pdf

No problem. I've had dead links before where the cut and paste from the browser's address bar didn't copy the full link. I just wanted to be sure.