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(Long post, sorry. Synopsis/TLDR at the end) Does impedance or cable length matter on a chassis ground for a mobile setup? I’ve read several posts and a couple articles about proper chassis grounding of the antenna (specifically the ground plane, and yes I know they are different) but can’t seem to nail this one detail down. Some sources say use an exposed grounding strap less than 10” long, others refer to grounding NEAR or TO the battery ground on the vehicle body (not the battery itself). I assume they are not using exposed braid for the multiple feet between their antenna and engine bay, (I could be wrong,) so potentially coax cable? But no mention of what kind. The only thing consistently stated (which makes sense) is to make sure both ends of the grounding cable actually contact bare metal. In my mind (not an electrician and new to radios) it would make sense for the ground to have less resistance than the input as it is the “escape route” for unused energy, preventing it from feeding back down the outer braid of the coax. On the other hand it also makes sense (in my head) for the ground to match the input resistance so it doesn’t allow energy to escape that should be turned into radio waves. Again, not an electrician, new to radios so I’m probably not thinking of this the right way! In case it’s useful, here’s what I’m working with conceptually at the moment as far as radio/antenna setup: I have a MXT575 and am waiting on a Larsen LP450NMO antenna to show up. I’ll be mounting it on a custom ground plane mount (24”x24” aluminum plate) behind the rear roll bar of my Jeep JKU with a hard top, high enough to clear the roll cage. The radio will be mounted directly under it, maybe 12”-16” of coax between the two. Before anyone asks, I am trying to avoid external mounting of the antenna as a personal preference. Also, short of drilling holes in my top this gets the antenna above the roll cage which is a plus! Synopsis/TLDR: 1: does cable length and/or type (shield vs unshielded) and/or resistance matter when chassis grounding a mobile antenna ground plane? 2: does grounding location matter? Thanks in advance for any info everyone!

Are there mobile units that operate with the GMRS pro gps function?

Hello everyone, I am a new GRMS licensee and this is my first post on this forum. So, it’s good to meet you all. I have been a computer network engineer for 23 years, worked in video streaming and conferencing, telemedicine, backend systems of all types, and I am now venturing out in the mystical world of RF. I have had very limited experience with the RF side of 2.4 and 5GHz WiFi and 4GLTE systems, and have loved two-way since I was a kid, but now I have the budget to really get into it. I have been researching how to link GMRS and stumbled onto this site and the grms.network videos. Then I looked into what the amateur radios folks were doing with Allstar, EchoLink, and the like. I am pretty handy with a soldering iron, know enough to be dangerous with Linux, and understand the IP side of it very well. So, I thought I would try my hand at building a deployable linked repeater system. What would be the use case, you say? Mostly because I am a geek and I think it would be cool. Beyond that, I can see it would be useful for events like marathons and adventure races, desert rally races, etc where someone was traveling in a linear distance and aid and comfort stations along the route needed to maintain comms. Distance in the desert, the ability to address terrain obstacles in adventure races in the mountains. That kind of thing. You could set up at night points along the route and blanket it with linked coverage. Or, that’s my idea for it anyway. A lot of it is pretty straight forward, and I have really appreciated the information many have shared about GMRS linking. I have a good handle on the I{P requirements and how to use LTE to provide the private IP control and repeater interconnection network. But a couple of things have really hung me up. How to interface the radio hardware to the node computer. There are some great videos online about how to modify a BF-888s to create a hotspot node, and I can extrapolate the connection to radios that have a 14pin, 9DB, or 25DB control connections, But how can you get into other mobile radios at 50W that don’t have a control port in the back? I have bought a KG-1000g to play with and I think it’s built in repeater capability through a control cable to an identical radio would keep the system pretty compact. You would need a duplexer, but not a repeater controller? So, the question is how to wire in to what the URIx (ideally) or modded USB sound card needs? If it can be done on the BF-888s, then I think it’s a question worth asking. The other thing is the Allstar server backend. Is it in the node package, or is that a separate package? If I can get these two issues moving, I think I can make something cool. At any rate, I will be around if anyone can use what I know. I am happy to tell you what I know and tell you if I don’t know.

Greetings folks. I have a question for the folks with more knowledge and experience than I. In my vehicle. I have a couple of pieces of radio equipment. Suggested power input is 13.6v to 13.8v. I have both engine power and solar/Lifepo to work with. Issues; As we already know; engine power is variable in most vehicles. Even more so with down step alternators in today’s vehicles. When alternator is operating, getting 13.8 to 14.6 volts is easy. Once engine is off, we are left at the mercy of most batteries, bleeding charge down to 12.2v or lower over time. With Solar; In light I charge up to 14.2v. At night my Lithium batteries maintain 13.2 to 13.0 Volts (depending on length of night). So once again this voltage is variable between 13.0 to 14.2 volts. So enough of the word vomit. What have folks done to regulate voltage around the 13.6 voltage range? I have seen folks who simply use cheap voltage regulators/inverters. But I have concerns about dirty power, especially as from time to time the construction is questionable, creating a number of radio issues. So I am curious as to what other solutions are available/recommended, or would a cheap voltage regulator/inverter be sufficient? Looking forward to input Thanks folks.

Howdy y’all, I made a high mount for my midland 6dB gain antenna for the back of my Jeep to get rid of this weird garble that happens while driving. I thought it was rf from the engine (part of it was) but now I think it’s picket fencing but it’s particularly prominent with weaker signals so I’m not sure, but that’s not my question right now. Take a look at the picture attached please. The all thread rod is grounded so I suppose it acts as a vertical dipole now. Does the length of said all thread rod matter? Either way, is my current setup going to hurt me at all? Thanks in advance, I appreciate you!

I discovered some cheap Chinese radios have subpar battery replacers for "mobile' use. The plug in power supply provides enough volts and amps for receiving, but not enough amps for transmitting. After poking around I found some guys using the LM2596 DC-DC buck/boost chip to get enough power to run their HTs in a mobile or base station role. As long as the power source supplying the chip pushes more than 1.5Amps the HT will transmit. I set my chip for 8.3V and wired it to female(?) 5.5mm barrel plug for greater flexibility.

Advice on mobile antennas. Would use mag mount. Have the Midland 275 radio and need REAL improvement from the included antenna. Not going to drill . Typical use is 3-5 miles between autos. 3 DB, 5DB, 6 DB Larson, Ngoya, Tram, Pctel, Laird, Diamond, other? Thanks ! Bud

Hi all, Looking for a place to get my mobile antenna tuned for GMRS. ya know the 462 -467 range . Hard to find a shop locally for this . I do not own an SWR meter nor do I have tools . My stomping grounds, N. E Queens (NYC) East to Long Island. Recommendations appreciated ! Thanks Steven

I bought one of the cheap ($15-20) DTMF mics for my Kenwood TK-880. I had programmed my radio for user PL selection, which allows you to change the PL tones from the DTMF pad. It was a waste of money, because it doesn't work. It seems to work as a microphone, but it doesn't ground the on-hook line through the mic button. That means the scan function is disabled. Not only that, but while the PL select looks like it's working, what it actually does is turn off receive PL globally. I had to remove power from the radio for a moment to get the PL decode to return. The seller advertised it as suitable for Kenwood commercial radios, including (specifically) the TK-880. Maybe it can be rewired to work; who knows. And maybe it works perfectly on a Kenwood amateur transceiver. I don't have a TM series radio, so I can't test that. But it certainly doesn't work as delivered on my Kenwood commercial rigs.

I have a GE Phoenix with a tag on it that lists a 463/468 repeater pair and 141.3 PL. It is a single channel rig with a switch for talkaround. I think it would make a perfect receiver for my repeater, thereby saving one of my TK-805Ds for mobile use. I did see a guy selling programming software and hardware, but at a price that would pay for a better radio. Anyone have any ideas on setting this radio up?

Ok, this is not a review per se. I can review some Alinco ham radios if you like, since I currently have them in VHF/UHF mobile, VHF handheld, and HF/6M mobile form. Suffice to say that Alinco makes some great radios. They really don't get the respect they deserve. Having said that, the point of this thread is to let you guys know about some radios you might not be aware of. They are Part 90; AFAIK they don't carry Part 95. What you do with that is up to you; I think that subject has been pretty well hashed and thrashed. Also, with either of these two rigs you will have to buy the programming cable and software. That will cost you an additional $45 or so. HRO (Ham Radio Outlet) has both of these. Probably some other sellers do as well. The DJ-A40T is a 5 watt, 128 channel handheld. It is currently about $90. The DR-438 is a 45 watt, 200 channel mobile rig. Its price is about $250. If you check them out at the Alinco USA website, you can download pdf brochures, owner's manuals and even (in the case of some of the amateur radios) service manuals, free of charge! Note that the DR-438 is about the same price as the MXT400, and it absolutely blows it out of the water. Of course, like I said you do have to buy the programming cable and software, and there's the whole Part 90 thing. Note that I'm not recommending that you use Part 90 radios on GMRS. Refer to the sticky notification at the top of this section, if you have any questions about that. Btw, no I don't work for Alinco. I used to be in the radio business, but no longer.

I just got two of these Kenwood commercial mobiles, from two separate sellers on fleabay. I had made an offer on one, bought another via "buy it now," and then my offer on the first one was accepted. Both showed up today. What attracted me to the 805s is that they are front-panel field programmable; no software required (although they can be programmed that way as well). Both of these rigs came with a mount bracket, mic and mic hanger. The one I made an offer on did not have GMRS channels programmed in; it had two 461 MHz frequencies. It's a little beat up but not bad, and I think the mic is a new replacement. I had to remove the top panel and move the jumper to enable front panel programming. Once I did that, programming it was a snap. I put the 8 repeater pairs in it and set up the aux button to enable "talk around" (simplex). I also put one ham radio repeater pair in it; a nearby repeater that a member here owns. The other one looks like brand new. I paid a little more for it, but still got it for well under $100 including shipping. It came from an actual radio store, and they offered free programming. I took them up on it. These are 16 channel radios. The seller emailed a Word form for channel information and I had them program the 8 repeater pairs, Talk Around for simplex, and the 9 interstitial channels for a total of 15. These are billed as 25 watt radios, but according to my cheap VHF/UHF meter, both are putting out right around 40 watts. I'll probably turn them down to 20-25 watts to conserve the finals. I've seen a couple of comments online to the effect that after programming, you have to return the jumper to the "user" pins before they will receive and transmit. Not true. The only reason for that jumper is to prevent the appliance operator from inadvertently (or otherwise) messing with the programming. It works just fine with the jumper in the programming position, and the great thing is that you can pull over and modify a channel in just a minute or two. Bottom line: I like these radios!

I'm fairly new, I'm looking for a nice mobile rig that does vfo, not a big fan of this computer programmed radio, I do operate a baofeng bf-f8, a Motorola m1225 .. Any help would be great Thanks Aleck, WQXQ966

I am looking to put a couple TK-8180's together to make a repeater as I got them cheap. Does anyone have any info on how to make this happen? These have the DB-25 connector in the rear so either the DB-25 or the mic jack I would guess there is a way to make this happen?? I have considered getting a Id-o-matic IV also so there is an id. Anyone know of the easiest way to make this all happen?

I've noticed some things that people are not looking at in relation to their mobile based repeaters. So I got bored and started playing around with Matlab and made a few graphs concerning common mobile radios that are used to build repeaters. This isn't a very extensive list as it only consists of most of the Motorola Radius line (includes Radius, Maxtrac, GM300, SM50/120, and M1225) as well as GE Custom MVP's. All of this was built off of data that is available in the service manuals. Even though I do own some Kenwood and Icom radios (I even have the data for Icom F221s and F420s that I measured off mine before my tablet crashed) I just don't have the service manuals currently. As I recover data or fix my tablet, I'll update with the F420 and F221 info for building Icom CY-420 and CY-221 repeaters. These graphs show how transmit power relates to duty cycle (something that should honestly be considered when building repeaters). Figuring out the required duty is for the owner/builder of the system to decide. The duty cycle is a percentage of a 100s time period (as stated in both GE and Motorola service manuals). The slope of the lines represents the efficiency of the transmitters, this can be used by both those building off-grid systems and for calculating heat produced. These numbers can be changed with other methods of cooling (air flow, heat sinking, etc.) but represent the environment the manufactures designed the equipment to operate in. Motorola Radius Motorola designed the 40W radio for a 15% duty cycle, which translates to 2000 kJ of heat for the chassis. Giving duty cycles as follows. The efficiencies for the different power levels are as follows: 25-40W = 23.2% 10-25W = 24.1% 1-10W = 18.1% GE Custom MVP GE designed the 35W radio for a 20% duty, which translates to 2160 kJ of heat for that chassis. The 25W and 5W radios are lacking something…the heat sink on the back of the 35W radio (it can be replicated with a P4 or similar CPU heat sink). As such there are two graphs for the 25W radio, one for a factory radio (20% duty @ 25W = 1160 kJ of heat) and one for a system with the heat sink. The efficiencies for the power levels are as follows: 21-35W = 24.5% 7-25W = 29.1% Again, all these were taken off numbers available in the service manuals.

So I mounted my Wouxun kg-uv920P-A in my car with the ability to hot swap it out and take it into the house to use as a base station. Unfortunately my inner sloth got the better of me (I got lazy) and I ordered a new mobile to keep in the house. So I picked up the TYT TH-9000 UHF model for $160.00. My initial thoughts: The manual is worse than Wouxun or Baofeng, there are instructions for features where the process does not produce the described result The user interface is just as bad, except the LCD does not display certain letters very well so it leaves you to guess at what it's trying to say The software is a bit better, allowing you to get an idea of the settings but you still need to keep the Engrish manual nearby to get a description of some of the features since they do not match the same naming convention as a lot of other radios The head unit is built extremely well, like a tank even, and it is fairly compact The mic feels a bit cheap and the functions on the mic are easier to perform from the head unit The "P" buttons (P1-P5) have different functions, they are not labeled, and their functionality can be customized from the computer softwareNow on to the functionality: The transmit power is nice, not many mobile units I have seen provide more than 40W so with 45W this radio is rather unique Once you figure out the interface (still keeping the manual handy) you can navigate the settings fairly easily The backlighting is bright, and I mean bright, but it can be turned down and comes in 3 colors: blue (too blue, hard to read), orange, and purple (weird right? but it is probably the easiest to read) Transmitting on this unit is nice, I was able to pick up the signal on my mobile crystal clear at 4.7 miles away The receive is where the real problem comes in (for me): There are documented reports of the squelch not behaving correctly when not using CTC or DCS (DPL) codes, it appears even on the lowest setting it is cutting out signals the have even the slightest chop or static The recommendation is to set a CTC or DCS for your channels and turn the squelch off, the radio has a setting to listen only to transmissions with these codes and cut out the carrier so you don't get the constant static noise This seems to work great and my mobile unit comes through just fine, but without doing this little trick my Wouxun mobile has static from just 1.7 miles away From the same locations I can transmit on my Wouxun KG-UV6D HT to the Wouxun mobile at my house and hear less static on the mobile at the house than when I use my Wouxun mobile to the TYT at the house The receive does not seem to be as sensitive as others I have used There is a repeater 31 miles away that I can hit with my Wouxun mobile and hear others on it, when I attempt to key up the repeater with the TYT I can not hear anything back I have checked the offset and CTC codes, and they match, I also programmed the Wouxun for the reverse of the same channel so they could talk simplex on the repeater channels and could confirm the Wouxun was communicating with the TYT For me, this unit doesn't meet my needs. Since I live in an area where there are few repeaters in range, I am constantly scanning GMRS frequencies with open CTC and DCS codes. With this unit I either must listen to the constant static or not be able to scan properly. For someone who primarily uses the same channels with the same CTC or DCS codes this unit would work great and at a great price! The product quality seems to be very good and it has nice features. I would recommend getting the programming cable (mine came with one) and software (free to download from TYT) as the UI is rather confusing and the manual is little help. Overall I would rate this unit a 3.5 out of 5 (mainly due to the squelch issues).