Jones

It is possible that your narrow-band Midland will not produce enough CTCSS tone deviation* to activate the wide-band repeater. * "Deviation" is the technically correct term for "modulation level" when speaking of FM.

I think this group coined the term "CCR" to mean what it does here. For 50 years before this forum, I, and many others used the term "CCR" to refer to a quartet of musicians: Stu Cook, Doug "Cosmo" Clifford, and the Fogerty brothers, Tom and John.

Most older FRS radios can't cover the Wide GMRS channels anyway, as most stop at channel 14. The original GMRS Wideband frequencies are now known as channels 15-22 on modern FRS radios - a leftover from the "Combo" radios of the past few years. You are correct however, in that this one is very narrow - not much modulation at all. Most UHF narrow band analog gear these days is 12.5KHz max bandwidth, and the most common designator if 11K6F3E. (actual 11.6KHz bandwidth)

I was going to tackle this project, and compile such a list. ...however, after researching radio and electronics related acronyms, shortcuts, and abbreviations for about 20 minutes, I realized that it was overwhelming, so the only one left for me to consider was OMG!. ...and I quit. Will be happy to answer one-at-a-time as needed, just not publish 14,000 at once.

Back in the old days, we used to have "CB Jamboree" events out here in the midwest that would bring folks in campers & RVs from across the nation. Perhaps one of these days, (not soon due to Kung Flu) but one of these days someone could host a "GMRS Jamboree" for the same purpose.... get together for fun, food, and fellowship - and have a big swap meet to swap radios, antennas, parts, and bushel baskets of bull.. uh, chips.

All it takes to publicize it more is for you to tell your friends, and tell them to pass it on. CH-20 (462.675) w/ 141.3 CTCSS is not written in any law, it has just been accepted as the travel channel long before I even got into this part of the hobby. It was part of the original "Open Repeater Initiative" - Google it. So go ahead, tell everyone interested.

Marc, I must add that I am a also very technical person, being a broadcast engineer, but that doughnut analogy of yours is spot on. A flattened doughnut will spread its contents outward from the center point - just like a stacked vertical antenna array - no doubt about it. Now... uh, where are those doughnuts? In my world, 12 dB = one dozen doughnut balls. Mmmm. I'll take those with RC Cola please.

Thanks for the writeup Marc, very good. ..except I have to agree with Axorlov, a quarter-wave antenna has a gain FACTOR of one, not a gain of 1dB. A gain factor of one, is in fact, zero dBd, or 2.15 dBi. An antenna that is rated for 3 dBd gain would have a gain factor of 2, thus a 10 Watt transmitter going into a 3dBd gain antenna would produce 20 Watts ERP. (effective radiated power) Each 3 dB of gain represents a doubling of power. Each 3 dB of loss equals a halving of power.

I have a wood 3rd floor attic on my old house as well. I do have a UHF antenna up there, and it works very well. - not as good as my outside antenna, but the results are excellent for what it is. I normally get about 3 miles to my handheld radios, and about 7 miles to my mobile. If you are going to put your antenna in the attic, just be sure you do not have metal shingles on your roof. ...also keep the antenna a few feet away from any old cast iron drain vent pipes that may be going up through the roof. PVC plastic pipes don't seem to matter.

Log back into the radio with the software, and make sure your front panel mic jack routing is set up to use the front audio input on front PTT, and that it is set for microphone, and not data input. I forget where this is off the top of my head, but it is in one of the option screens.

On the ones I got, it isn't just a simple matter of unpluging the AUX cables from the header connectors on the board. Mine have a couple of wires that have been cut from the plugs, had extension wires soldered on to them, and they run up into the head-shell and solder onto points on the control PC board. There are also other wires that seem to have been cut/spliced inside the radio that go to the AUX connector, and there is an adapter (might be custom-crafted) that plugs into the AUX connector, and goes to a DB-15 socket. I think I was on email with you before about these, and I just set them to the side. If you still have my email, let's start back up a conversation. I may just ship these to you so you can take a look.

That is likely due to capacitance coupling of the ground plane. That is a mag-mount antenna, so the ground plane is not DC coupled at the base of the radiator.

True. And the higher gain they are, the more narrow the bandwidth will be, and more difficult to tune. There are no antennas that have enough bandwidth to be used from 420 MHz to 470 MHz without tuning, but the most bandwidth coverage is from quarter-wave antennas, which are about 6 inches long. A quarter wave can cover from 433 to 468 with good results and fairly low SWR. ...and watch out at ham fests and flea markets for quarter wave UHF antennas that seem too cheap. I saw a guy once selling UHF quarter-wave NMO antennas for $1 each. I measured one, and it was only 5-1/4 inches long. Those are to cover 470-512MHz, and won't work for GMRS or ham. If they are too long, you can grind them down. If they are too short, . . . _ _ _ . _ . . Guys, if you are looking for a super high gain antenna for both Ham and GMRS use, just give it up. There will be a compromise on one end, or the other. If you must use just one antenna for both UHF ham and GMRS, then use a quarter wave tuned to 450.

I got 2 of these from eBay that have the exact same issue. They both have the same modifications for some digital in-out port on the back. I just set them aside for now. If I ever figure out what has been modified on these, and get it returned to normal, I'll post details here.

It's a "Snake Radio Custom". In my opinion, a clueless "screwdriver expert". Keep in mind Marc, the SSB power control in these radios is useless and no longer functional when the ALC transistor has been clipped out for "Maximum Swing" or whatever. ..and Jesse, If it were a clean 100, or even 500 Watts at 27 MHz, it would in no way harm the Motorola UHF front-end, however this thing with its un-filtered chinese-made amp slab is very likely going to be grossly dirty on the spectrum, so no promises. The only thing I can promise you is that no oscilloscopes, or spectrum analyzers, or professional technicians were used in the tuning of this "Super" radio. Quote from "the snake" himself from forums.radioreference.com: "I am old school and I tune and align the radios buy ear and my pep meter and my bird wattmeter and my signal generator and DB meter for receiver peak settings . I have had people take radio`s that I have done to other shops with all the spectrum analyzers and scopes netc etc put my radio on there equiptment and it was right on the money." Sure, I'll bet. I ran a CB shop in Salina Kansas back in the 80s and early 90s, and I have seen and repaired thousands of these butcher-shop customs. These days it is even worse with the influx of cheap Chinese and Italian MOSFET amp modules. If you are really worried about your UHF being overloaded, use one of these filters between the output of your CB amp, and your CB antenna: https://www.dxengineering.com/parts/mfj-704 That will filter out anything above 40 MHz to protect your other VHF and UHF radios, and prevent interfering with other services. It's a pricey accessory, but it might be worth if for you, and it will certainly handle all of the power you will be able to throw at it. Be sure to use a high-grade RG-214 coax jumper between the amp output and this filter. OK, now that I have upset everyone, I'll sign off for the day.

Go here: http://www.arrl.org/shop/What-s-New ...and type "Books" into the 'Search Store' box, next to 'shopping cart'. You will find a ton of good stuff there to buy and read. Also note that many ham radio clubs provide these ARRL books to local public libraries, and you can check them out at no cost.

Heat has not been an issue with my Kenwoods. They will not get hot enough to set anything on fire, or melt plastic. They will need a bit of airflow around the heatsink however, so don't bury them under anything, or mount them in an enclosed area without ventilation.

As for a recomendation for cable between your duplexer and your antenna, if you are going 100 feet, you really shouldn't go anything less than 1/2 inch semi-rigid transmission line, or "Hard-Line" such as Commscope/Andrew LDF4-50a Heliax. That can be found for under $3 per foot. Expensive, but owning a repeater isn't cheap. We've mentioned that before in other areas of this site. An even better solution would be to jump up to 7/8 inch line, such as LDF5-50a, but that gets you close to $8 per foot. In my opinion, Commscope/Andrew is the best, but there are also less expensive transmission lines out there, such as Eupen, which you may find at a better price. Make sure to buy the correct connectors for whatever brand of transmission line you buy. Those connectors are not interchangeable between brands or types.

Another pro-tip: Do not tape or tie-wrap the RX and TX cables together going into your duplexer to make them look neat and tidy. Keep those cables as far apart as possible. At UHF, those cables should also be a foot long or less, unless you are using Heliax or Superflex coax. (If you can afford them, pre-made Andrew Superflex jumpers would be even better than RG-400)

NOTE: RG-400u is NOT the same type of cable as LMR-400 or DX-400. RG-400u is a smaller diameter, double-shielded cable, the size of RG-58u, for use as jumpers in a repeater system, or internal radio connections where signal leakage would be a problem. LMR400 from TImes Microwave and its clone, the DX400 cable from DX Engineering is a larger cable, the size of RG-8u, that is supposedly rated for use up into the 400 MHz range with low-loss. It has its uses, and can be great for a GMRS base station, but not a repeater where it has to transmit and receive at the same time - that is where the trouble starts. RG-400u, and its larger cousin RG-214u are Mil-Spec double-shielded, silver plated cables, specifically designed so that the signals between two closely-ran cables will not cross-talk into one another. That's what you need is a repeater system.

I still think you are describing de-sense. The one weak link you have in my opinion is that knock-off LMR-400 coax cable. I also still wonder what you are using for jumpers between the radios and the duplexer. Cheap CB coax jumpers will NOT work for that purpose.

If you want something lightweight that folds down for "just grab-and-go" temporary use, I have had good luck with PA system speaker stands such as: https://www.parts-express.com/peavey-tripod-speaker-stand-ii-56-102-black-100-lb-capacity--248-8586 Add a 5-foot mast pipe to the top of this, and your antenna is instantly 12-15 feet in the air. Add some rope and tent stakes for temporary guy wires if it's windy.

Another tip I use: Program channels 1-7 as Narrow bandwidth, since most of the time on those lower channels you will be communicating with FRS handhelds. Leave the upper channels wideband. Repeaters for the most part will be wideband. When programming repeater channels, the TX frequency will be 5 MHz higher than the RX, thus you would type in 462.625 for the RX and 467.625 for the TX frequency. You will also need to add the tones required, which will be those QT boxes. QT Enc is the tone you are sending to the repeater, and QT Dec is the tone you will use to hear the repeater, or you can always leave the Dec column blank to hear all traffic on that frequency.

There will also be a separate screen you can bring up to program what the various buttons on the front panel do. We'll touch on that later. Get at least one channel active and working for now.

For testing, and to learn, type the following in to row 1: under RX Frequency, type in 462.62500. under TX Frequency, type the same thing: 462.62500 QT/DQT is Kenwood's trade-name for CTCSS or DCS a.k.a "Tone Squelch" - Decode and Encode - just leave those both blank for now. under Channel Name, type "Channel 18" under W/N, select Wide instead of Narrow, unless you are talking to Midland MicroMobiles or other FRS radios, then select Narrow. Under TX Power, select Low for the time being. You will change this later, remember, this is just for testing and practice programming. Scan Add - Yes (or no, doesn't matter yet) Optional Signal - leave it blank or select None. Then drop down the program menu from the top bar, and select "Upload data to Radio" and go from there. Your radio should re-boot after a minute or less with FRS/GMRS "Channel 18" showing in the display, and you should be able to talk to another radio on 18 with no private code set. (Private code is Midland's name for CTCSS or Tone) If it works, go back and program in channels 1-7 on Low power, and 15-22 on High power. You can add repeater channels later as needed. To find the frequencies to use, just do a google search for "FRS GMRS Frequency Chart" and you'll find it. Also note that is is illegal to use FRS channels 8-14 on a base or mobile radio, so just leave them out. Those are for half-watt handhelds only.