Lscott

So in the case of that radio it does appear you can mix TX and RX frequencies so I off base on that one. I guess I should be more careful about making statements on radios I haven't really used. Thanks for pointing it out. In any case one can use that radio and try out the split frequency operation for fun.

VHF marine HT’s might be the way to go as long as they are used on the water. They are license free as far as I know. Many if not all will float if dropped into the water. Something a GMRS HT likely won’t do. Nothing worse than watching a $100+ radio sink out of sight.

You advocating the use of uncertified radios on GMRS? I'm not. Also this part I guess you missed, "the cheap frequency preprogrammed radios", does not apply to the UV5R type radio since it is freely frequency programmable. Radios such as the 805, 905, 935 and similar from other manufactures etc. have preprogrammed TX and RX frequencies you can't modify and are commonly used for GMRS.

It's also not Part 95 certified. I'm talking about radios certified to use on GMRS.

I would venture to say a number of people have operated in an illegal manner, modes, power etc. a few times or routinely. I would hope they know the rules and understand the consequences if the FCC notices. At least they are smart enough, most of them anyway, not to publicly advocate or mention what they are doing, it sets a bad example for the newbies.

If you wanted to keep someone from using your repeater with the cheap frequency preprogrammed radios then picking a non standard frequency split would do the trick. Since the rules don't require one to use a 5 MHz split you're free to pick from any of the 8 TX and any of the 8 RX frequencies for the repeater. The only radios that will work in that case are modified radios and commercial Part 95 certified radios which you can independently set the TX and RX frequencies. Also the same idea will work to frustrate simplex jammers. Radio one will TX on F1 and RX on F2. The other radio will TX on F2 and RX on F1. Both frequencies are legal simplex channels. Each user can have several channels programmed up with different combinations of TX and RX simplex frequencies and switch between them, memory channels, as conditions demand. To do this with more that two radios is not as simple and would likely require some method to scan several channels very rapidly, a programmable home or priority channel feature etc. As far as I can see there is nothing in the rules that prohibits this either. So long as your operation is not causing interference, as you pointed out, it should be OK.

People need to read the rules before believing some of the stuff they get on the 'net. The rules don't limit the number of repeaters, just the number of frequency pairs, GMRS "main channels", they can use, currently the rules list 8 RX and 8 TX frequencies. As a side note I don't see anything that requires the RX and TX frequencies to be exactly 5MHz apart either so long as you use one of the 8 TX and one of the RX ones listed in the rules. https://www.ecfr.gov/current/title-47/chapter-I/subchapter-D/part-95/subpart-E/section-95.1763 You can have as many repeaters as you want on a frequency pair so long as the frequency is shared with other users.

https://www.youtube.com/watch?v=HNLQ-O-Qx3Y

By an inline attenuator. Put that on the output. I got this one used for about $50 a while back as an example. I also have a set of low power Weinschel's to use with an old HP power meter. Narda Fixed Attenuators.pdf Models 1 and 2.pdf HP432A Specifications.pdf

Try the attached files. Canada VHF LADD Channel List .pdf CB Radio Around The World.pdf Civil Air Patrol.pdf Common Itinerant and Business.pdf Freenet-2.pdf KDR444.pdf 1156812829_PMR446WhitePaper.pdf Railroad - Scanner Frequencies and Radio Frequency Reference.pdf VHF Marine Frequencies - 1.pdf

I looked it up since the official RR frequency list can be found in the attached file and the ones you listed didn't look like what I expected. Of course there could be additional ones assigned by the FCC for special uses. Got curious and had to check. I have a code plug written with all of the official VHF FM and NXDN digital railroad channels for a Kenwood NX-200 radio. The portable radios used mostly by the railroads are from Kenwood and Icom. https://comms.kenwood.com/common/pdf/download/02_NX-200G&300GBrochure.pdf I haven't really tried it yet. If anyone is interested I've attached a copy. It also has some of the Ham 2M simplex channels, MURS and the VHF NOAA weather frequencies too. With 512 available channels it wasn't much of a squeeze. Railroad - Scanner Frequencies and Radio Frequency Reference.pdf NX-200 Railroad 20220422.dat

Very unlikely. If one wants VHF access use MURS. Want HF access use 11M CB radio. Want more channels, power, repeaters and bands get a Ham license. That's going to be their logical response.

I did a search on the FCC site for the exact frequency of 151.625 just to see what pops up, a HUGE number of hits. Only a few look like they have anything to do with railroads. 2187 WREJ974 RAILROAD CONSTRUCTION CO OF SOUTH JERSEY, INC. 0028698892 IG Active 10/17/2029 2188 WRFR834 RAILSERVE INC 0028619906 IG Active 04/20/2030 2189 WQVF999 Railworks Track Systems 0024232860 IG Active 01/30/2025

Given the frequency split between the 151 MHz and 154 MHz frequencies that wouldn't be too hard. Of course it isn't legal.

Yes, they already have several modes in use under their license free PMR service. They have the narrow band FM, similar to our old FRS, the low power DMR and Digital PMR. The issue is getting the FCC onboard with doing any kind of digital voice mode on GMRS. They have been very resistant to the idea. 1021937093_PMR446WhitePaper.pdf

The hood location will compromise your range. The better place was on the roof. I had a roof rack mount on my old Jeep. The cable ran down the side of the rear hatch opening. I used some duck tape to hold the cable in place along the opening and then ran the cable through at the bottom with a “drip leg”. The hatch door covered up the tape so you can’t see it. That way any rain would run down the cable and not get through the hatch seal.

Interesting comment. I think those channels could be put to better use IMHO. In another thread there is a suggestion to use those interstitial channels for the addition of digital voice mode. Using a narrow enough digital signal overlap with the "official" 20KHz adjacent GMRS main channels could be reduce to less than the current 11KHz narrow FRS FM, or eliminated. There are some digital voice modes that only use 4KHz bandwidth and would fit in without overlapping the GMRS main channels. Might even run at much higher power too, like at least 5 watts, the limit for hand held GMRS radios.

This is another model file for a 5/8 wave MURS antenna. In this case there are 4 horizontal ground radials. Beside a series inductive element I need to use a 1/4 transmission line matching section to bring the SWR down to near 1:1 at the design center frequency, that's between the 151 MHz and 154 MHz channel frequencies. Without the transmission line matching section the match isn't that great. Looks like the radials really should be angled downward. I also tried a J-Pole model at MURS too. MURS J-Pole Rev 2.EZ MURS Five-Eights Wave GP - Rev 3.EZ

Antenna modeling takes some intuitive insight. Also have to get a feel for the limitations of the modeling tool(s) as well. The high segment count I used was to keep the feed point and series inductive load located at the bottom of the main vertical element. The 5/8 wave antenna requires a series inductive element to match correctly. The dual band antenna I haven't tried to model yet. One reason is you need multiple elements, at the higher frequency, in series using phasing elements or line sections to get the element currents to line up phase wise. Trying to figure out how to do that with a modeling program will take time and good educated guesses on how to do that and get believable results.

https://www.icomamerica.com/en/products/landmobile/portables/v10mr/default.aspx https://www.icomamerica.com/en/products/landmobile/portables/v3mr/default.aspx

The FCC wants either 6.25KHz bandwidth or the equivalent at some future point in time. When that might happen is anyone's guess. DMR can do the "equivalent" part since it can run two voice streams in a 12.5KHz channel bandwidth. The one attractive part of DMR is the ability to build a repeater without the necessity of using expensive and bulky cavity filters. This is the so-called SFR, single frequency repeater. The hand units would TX, for example, on slot 1 and RX on slot 2. The repeater would RX on slot 1 and TX on slot 2. All of this transpires on the same frequency. To change the repeater frequency simply requires switching to another frequency by all involved users. No cavity filter re-tuning required. I've read many comments about how one mode sounds better that another. Consider that DMR, P25 and NXDN all use the same exact vocoder, the AMBE2+, which can run at two different data rates. When running the same data rate, NXDN has two by the way typically offered by Kenwood radios, any differences likely has more to do with other factors with the radio and not the mode as such. Otherwise they should all sound about the same based on the vocoder itself. Where things get sticky with DMR is when a particular site has no need for the extra voice stream, effectively it goes to waste so you end up with one voice stream occupying a 12.5KHz channel. Unless two separate sites have radios with DCDM, duel capacity direct mode and within range of each other, the radios can't sync to a master time slot signal. You also then have to coordinate between sites who uses which time slot etc. This would just make the job of the frequency coordinator far more difficult. The job of the frequency coordinator is to reduce or eliminate interference between sites by distance and frequency diversity means, just the opposite of what DCDM would require. A true 6.25KHz bandwidth would allow the frequency coordinator more flexibility to assign channels since there would be more of them, physically, due to the narrower bandwidth possible. Not every site out there needs a repeater, the usual source for the master slot timing signal, simplex communications works fine for them. This point is very often overlooked by proponents of DMR.

Try this model file. Five Eights Wave Rev 5.EZ

I just wonder how well it's going to work since the cable/wires are not shielded. The cable/wires go right through in close proximity to the RF power stage. You might have been better off punching a hole in the bottom or side of the face plate and running the cable through there. As a side note I have one of these radios and I'm not impressed with the receiver performance. The radio has poor selectivity in the presence of strong in band signals. A few channels I've had to lockout due to fire paging calls, some from 10+ miles away, showing up on channels I'm sure they really don't operate on. I don't pick these calls up on my other radios. I guess for a $110 CCR ,what I paid, that shouldn't be a big surprise.

Unless the state reserves that format block there isn't isn't anything you can do about it. Contrasted to Ham call plates, at least here in Michigan, you have to show proof of your license before they will issue the plate. The fees are the same as an ordinary plate so you don't pay extra for it. At least I've never noticed if they did charge extra.

There is a wide spectrum of charge controllers. What he needs is very dependent on the particular equipment, batteries and panel array. If the panel array/size is large compared to the battery bank then try to find a charge controller that can be "programmed" to limit charge current, voltage points etc. I have several "good" charge controllers from this company. https://sunforgellc.com/product/gv-5/ My solar panels range in size from as small as 5 watts up to 100 watts. I pick the panel size to match the charge controller and battery pack I want to charge, I have several LiFePO4 types from 3.3AH to 40AH. However the charge controllers I have are not "programmable". So, what is a "good" charge controller in one system design may not be so good in another.