Radioguy7268

Samlex makes some decent 24 to 12 volt step down converters for around $100. No matter what, pay attention to the Amp rating, the cheaper ones are often limited to just 10 or 15 amps advertised, which might be under what your 50 watt radio will pull under transmit. (Note that the actual ratings are often less for continuous draw - as compared to the "advertised" max instantaneous rating.) I wouldn't get too worried about DC noise getting into your radio from the converter. More noise comes from bad grounding and alternator whine. If you're planning to use a 1/2 wave antenna, then no ground plane should be necessary. Fender mounts are not ideal, but they work. Fender mounts will far exceed the range of any portable you're talking simplex with. You're asking good questions - but don't let perfection become the enemy of good. Your setup will be good enough.

I live and work in the real world. LMR400/LMR600 is what we use in probably 75% of our installations for repeaters. Price/performance, the stuff is hard to beat. Plus, it's easy to install & holds up well - provided that you install it correctly. That means that you need to shrink wrap the connections & use mastic on any outdoor connections. Keep the line secure & don't let it flap in the breeze, keep water out of it, and you'll see 15+ years out of it IMHO. When I have pulled LMR400 due to noise or "the Rice Krispies effect" it's almost always been soldered on PL-259 UHF connectors. I did have a recent replacement of a customer's LMR400 that was 20+ years old & was showing noise during the repeater tail. Once we got up on the roof, we discovered that the real problem was a cut in the line due to a recent roofing job, not really a failure of the cable due to install or age. When I do installations where the line runs are over 100 ft, or when the budget allows, then Heliax is my go-to favorite for UHF or VHF. I find more problems typically with the jumpers used for duplexers than I do with LMR400. Pay attention to the quality of your connectors and cabling used at ground level before you spend big money on heliax. There is sense to the idea of buying quality one time, but there's also a realistic factor.

Phantom antennas suck. Do a simple test: Put on the Phantom antenna, run your VSWR test, then step back 10 ft. from the vehicle & tilt your head 10 degrees to the right. Now, screw on a standard 6 inch hatpin UHF quarter wave antenna, measure VSWR again, and then step back 10 ft. and tilt your head 10 degrees again, this time to the left. I'm thinking the 1/4 wave hatpin will look much better after running your test. The 10 degree head tilt is optional.

The R1225's were famous for burning up if you ran them at high power. Someone probably did you a favor by turning down the finals to limit the power output. The sales brochure said they'd do a 50% duty cycle at high power, experience says that even at 25 Watts, anything close to a 50% duty cycle would kill them. Lots of the later Maxtrac/Radius mobiles that the R1225 series were based off of had a thermistor controlled limiting circuit that would turn down the power as the amp heated up - kind of a self limiting feature to keep the radio from burning itself up. I haven't dug into the manual for one of those R1225's in probably 15 years - so I can't say for sure that's what is causing the pull-back that you're seeing, but it seems like it might be. Make sure you're keeping the fan on & blowing cold clean air across the heat sink. Either way, if you want more than 20 watts out of your R1225 repeater, you should either get an external amp or go find a nice used MTR2000. I'd also say if you're trying to crank more than 20 watts out of your duplexer - what are you talking to? Portables at 4/5 watts? How far can they talk back in? Transmit power sounds sexy, but it's rarely the limiting factor in a repeater system.

Anything electronic is built overseas. Even Motorola doesn't do much in the USA except assemble parts built elsewhere. There's a pretty big issue with component supply right now due to some of the political wrangling that's been going on, tariff's, etc. There was a fire at a semiconductor factory in Japan (AKM) that's causing all types of trouble for Kenwood - but it's supposed to be affecting other products like some Ford Trucks and Tesla that have idled assembly lines for certain models. Rumor has it that another chip manufacturer had a plant fire in March - Renasas in Japan. Most of the rare earth metals are being mined in China. Batteries and semiconductors are not "green" when it comes to manufacturing. The USA has effectively off-shored most of it's pollution by having everything built overseas. I'd purchase what fits my budget - with an eye towards resale value. If it's $100 but has zero value once used, it is junk. If you want to support US business - consider your local radio shop. They probably have some well built equipment hiding on the back shelf that would work well for GMRS.

A remote mounted head would be a big help. There's very few options for a traditional install. Most of the dash & console are plastic, with no good options for mounting a heavy brick. You can also get an advanced mic option RMN5127 - or the full tilt PMLN7131 Hand Held Control Head mic (costs darn near as much as the radio - but makes mounting a breeze.) Either one of those allows you to hide the brick under a seat or behind the seat, and then control the radio via the mic. Having voice announcement enabled helps a bunch with the more limited RMN5127. If you go with the hidden radio - then you're probably going to need a mic extension cable - Motorola makes a few in different lengths - the PMKN4033 at 10ft or the PMKN4034 for 20 ft. are the ones we use most often.

Here's what Google says: https://www.rtsystemsinc.com/ST-980Plus-Radio-Programming-Software_ep_419-1.html In 25+ years of Commercial LMR experience, I have never heard of the Socotran brand - or RT Systems. Update: Well, that was an interesting little trip down the rabbit hole. Seems that QYT also makes an ST-980plus, and it's probably the same unit. You could probably try programming with Chirp - and select the QYT version to see if that allows read/write access to the Socotran. There's also a well-written write up done on the Socotran ST-7900 radio here: https://ka7oei.blogspot.com/2019/02/a-hiliariously-bad-multi-band-radio.html The guy does a very complete and thorough job testing the radio, and points out some of it's flaws - but also explains why it's happening, and why it's bad. It's a good write up for anyone who wonders why so many of us rail against the CCR radios that have come to dominate the lower end of the market.

When programming the CDM series of radios - you will need to pay attention to the "Personality assignment to Zone" tab way down at the bottom of the programming tree. Basically, when you add a new channel into "Personality" and set it up with Frequency and PL, etc. you're still not done. You need to drop down and assign that Personality to an actual channel position within the Zone. It's a little strange, but once you understand it, you'll do fine. There's also a "wizard" setting that might help you. Signaling is probably not where your problems are - it's mainly used for Push to Talk ID or Selective Calling. If you don't know what those items are - don't worry. You don't need them to access 99.89% of repeaters that are out there in the GMRS world. I don't have a codeplug available at the moment, but if you're still having trouble come Monday - shoot me a message and i'll get you a copy of an example codeplug for GMRS.

I've run the Tram 1486 on GMRS before with no problems. Range of 10-15 miles with a decent repeater. That's not to say every Tram 1450 is good, because I'm sure that some are junk, but it's not the design that's junk - just the tuning and the materials they're made of. Oh, and those UHF SO-239 connectors should be banned from the antenna industry. That said, have you tried out your antenna & coax just using simplex & hooking it up to a handheld or mobile? That will quickly tell you what's going on. Eliminate the repeater/duplexer/jumpers - just use an adapter straight to the coax feedline. If that doesn't work, then you KNOW it's the feedline or the antenna. If that simplex test works, then you've got some investigation to do. I'd want to sweep the line before I'd just replace the antenna. A basic UHF hatpin antenna would get you 2 miles on a working repeater. Heck, I once had a hospital with a repeater antenna blown off the roof & the connector ripped out of the feedline - that was still giving them 80% of their in-building coverage. They only called because "it was a little scratchy in some spots".

If you don't have the tools for testing, your choices are limited. You can take your radio to a local shop to be bench checked - but checking isn't necessarily fixing. If you've got another radio to try, then you should program that up & see if you have a different experience. If both radios are doing the same thing (but those cheap company radios are not having trouble) - then I think you need to look at the idea that the DPL information on Radio Reference probably isn't correct - it's just what someone's scanner read out.

Without getting into the weeds of technical jargon - there are design specifications that determine the size of the "window" that a radio receiver will recognize as being a properly configured DPL code. That design window allows you to not quite be exactly on target, but still close enough to the bullseye to count as valid. As long as your radio stays within that window, you're going to operate. Deviate off center a little to the edges, and the receiver might decide that you're not really a valid user. Start outside the window, and then drift into spec, and the receiver might take a while until it decides that you're really supposed to be there, and opens up the audio circuitry.

Back up to the issue that WPXM352 brought up - how did you get the Frequency and Code? There are certain PL codes that can "false" as a DPL - and if you read the DPL off the air with your radio, it's possible that you're close, but not quite there. The idea that it's taking so long for your Gateway device to recognize your particular radio as a Valid User indicates that there's something not quite right with the way your radio is presenting itself. I hate to say, but there's also shops within the industry that will NOT give out PL tones correctly if a customer calls in looking for system information.

Simplest solution would be to just try a different radio (prefer a Part 90 type accepted radio of proven design/performance) and program in the same frequency/code combination. Beyond that, you could put your current radio on a Service Monitor & see how well it's actually performing, ie: How stable is it? How well does it hold the programmed center frequency - what's the amount of drift? What's the deviation level and stability of the DPL? What's the total deviation? When you programmed your radio - did you set it for narrowband 12.5 kHz? Pretty much any UHF business band frequency would be a 12.5 emissions mask.

Chances are that the device is having trouble decoding your particular DPL, as generated by your radio.

Not knowing what kind of radio you're using, or the exact style of headset you prefer, I'd point you over to Impact Communications & tell you to browse through what they've got available. I'm thinking you can buy directly from their store even without being a dealer if you use a credit card. Their quality is pretty good, the pricing is decent, and their service and selection is better than you'll find at any of the "big box" online stores. When I go searching for audio accessories, Impact is my first stop if I can't find what I need through OEM. http://www.impactcomms.com Klein is another option - and they have some Bluetooth options that other manufacturers don't carry. I'd recommend Impact over Klein. http://www.kleinelectronics.com

I'm pretty sure that the FCC would tell you that you need to identify on each and every channel that you're transmitting on. That's kind of the whole concept of ID'ing - it's a way to identify who is transmitting, so that any issues of interference can be more easily resolved. If you transmit on channels 1,3,5, and 7 - but only transmit a partial ID on Channel 5 and 7 (because the radio switched channels halfway through your voice identification) then I don't think you've properly identified. How does the radio accomplish monitoring the channel to make sure it's open and available before automatically switching?

I wonder if anyone has pointed that out to the FCC? Seems that an automated frequency hopping system in GMRS would not be monitoring the channel prior to each transmission as it hops around - potentially causing interference to anyone who is already transmitting on the channel. I'd also wonder how it handles identification on the 4 channels that it just transmitted on. Or, do you need to stop every 15 minutes to go back and manually key up on the channel(s) in question and properly identify? Type acceptance under Part 95 probably doesn't allow for such a feature. I'm not a lawyer.

What happens when you add a 3rd Radio into the mix? You can decide to program it to either your A or B profile, but then when you try to key up on the 3rd radio - one of the other units (which is programmed the same as your 3rd unit) isn't going to hear what's being said. Taxi cabs used to do a setup similar to this in the 1950's and 60's on VHF. The dispatcher keyed up on a 152.xx frequency, which all the mobile radios listened to. The mobiles would talk back in on a 157.xx frequency - and the dispatcher normally had a separate receiver tuned to that receive channel - even when he/she was keyed up & transmitting. Taxi units could not hear each other, and could not talk to each other, which eliminated chatter between units. Unless you want to enter your Louie DePalma Dispatcher mode, it's not very useful beyond 2 units.

The actual M1225 LS model was a distinct version of the radio. Just to make things confusing, there was also an LTR "add-on" option board that could be installed into a regular M1225 to make it into an LTR capable trunking radio. The M1225 LS had limited "conventional" modes- I believe it was only 2 conventional non-LTR channels, and I also believe the early models required you to power up on an LTR home channel. Later versions of software or firmware fixed that. The most recent version Motorola M1225 programming software - HVN-9054 - will do either the conventional M1225 or LS models. Earlier versions of software was split into two different versions if I recall (20+ years ago) correctly. Make sure you get the latest, and it won't be a problem. The M1225 LS radio probably has a duty cycle of 10 to 20% when run at 40 watts. It was never designed or suggested to be used as a repeater by Motorola. I'd set the thing to LOW Power and run a cooling fan on it the entire time that the repeater is on. The heat sinks on the M1225 series is not very big. Keep it supplied with fresh cool clean air. Internal shielding was also not the greatest, and the M1225 series was known to suffer from desense. Get some physical separation between the transmit and receive radios, even if it's just 6 or 8 inches. Don't stack them directly on top of each other. Also, those inexpensive repeater maker cables that plug into the back of a 16 pin option plug can go in either way. Make SURE you're plugging it with the correct orientation up/down. There's only one way that's correct, but the incorrect way will brick your radio. https://www.repeater-builder.com/motorola/manuals/m1225-service-manual-6880904z96-a.pdf Pages 54 & 55 have the pinout information. If you didn't already own the radios, I'd be telling you to find another radio for the project. I like M1225's - but I don't like them for repeaters that have any type of duty cycle. I've made a few "poor man repeaters" in my life, but I usually used the low power M1225 models for the transmit side, and set them down to 10 watts. With a fan. And a time out timer set at 60 or 90 seconds.

All radios were programmed Wideband, and performance verified prior to shipping with an Aeroflex/IFR 3920.

Compander = Compression & Expander. The idea of a Noise Blanker - at least as I understand how it was implemented in Low Band radios by Motorola - was a secondary receive circuit slightly off-set in frequency, and that would be used to compare desired signal vs. undesired noise (Figuring that most lower frequency "noise" would be wideband in nature, while the desired signal would be on-frequency). In Compandering, Audio is compressed upon transmit, and expanded upon receive. This allows for a potentially better "envelope" of audio response to be compressed into a given amount of bandwidth. However, it requires more manipulation of the audio components of human voice. You give up a bit of audio purity when using Compandering. Better or worse is often up to the ears of the people using the system (and in my experience, how often the people using the system are pressing the outer edges of coverage/range). There's already a ton written about this type of stuff out there on the internet, so the best way I could describe it is to say that if you're only concerned about quality of audio within your own fleet - give it a try & see how it works on your radios and in your system. If you like it, certainly use it for your system. However, most GMRS radio systems and user groups aren't running Compandering, so your radios would sound "odd" sending out compressed audio to another radio that wasn't set to receive (and expand) the compressed audio.

It's "better" in that it would use Windows based software, it's capable of either Narrowband or Wideband per channel for programming, and it's a newer design. Beyond that, if you're a Wideband GMRS user - it doesn't matter much. They both work well, and the 880 is usually a bit cheaper in the used radio market.

A 1/4 wave 6 inch 'hatpin' antenna every day of the week. If you don't like chrome, get one in black. Get a spare or two in case she runs through the car wash. Cost is about $6. Retail.

Be cautious. There's plenty of "surplus" Public Safety radios hitting the market that are 800 MHz units. They're never going to work on GMRS. If the seller is willing to program 16 channels for you - go ahead and send them your list prior to purchase. That should give you a clue if the radios would work - at least, if the seller is honest...

Used DTR's seem pretty tough to come by at a cheap price. At least, in the Ebay world. They certainly do seem to have a following. I've traded in a few from Construction and Quarry sites where guys bought them without realizing that they couldn't talk to existing conventional VHF/UHF Digital radios they already had. Similar to Retevis' advertising people, they had confused DMR Digital with FHSS 900 MHz Digital. FHSS is neat stuff when they're picking out usable signals from low, low down into the weeds of the noise floor - all while hopping around at 100+ times per second, and avoiding interference on the fly.