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Everything posted by Lscott

  1. This is EXACTLY what GMRS is for, family comm's and with other users. I would say go for it. Your point about locking the radios to a specific channel is also an excellent idea. One it keeps the kids from messing up the channel settings and not understand why they can't talk to their friends. They WILL play with the radio buttons. Second as you pointed out it also keeps them from skipping around the channels like an electronic form of hide and seek annoying the crap out of other users. I have a family near by me that does this. I never know what channel they will pop up on and sometimes change while playing radio. Third you do want to make sure they don't end up on a repeater output channel. Young kids will just hit the PTT button and babble away even if the channel is in use. You can't expect kids that young to understand channel sharing. Even a low power FRS radio can wipe out the signal from a repeater if the FRS radio is close enough to another user's radio engaged in a repeater comm. FRS radios unfortunately are allowed on repeater output channels 15 through 22. Forth it keeps the kids from getting "glued" to the computer screen. Finally if the radio gets damaged or lost, young kids have a tendency to do both, it's likely cheaper to replace than a smart phone.
  2. You have some good points marcspaz. About it being market driven, wide band verses narrow band, could get a boost by the manufactures. If they are already narrow band compliant it would be a marketing incentive for them to point it out to customers. Second any wide band equipment only, mostly used, would be eliminated from the market. Now users are pushed into buying more from the narrow band new equipment market and less from now smaller compliant used equipment market. On the regulation front manufactures could point out to the FCC they have good sales of their narrow band radios and few requests for wide band equipment. The FCC could then infer the consumer has a preference for narrow band equipment, or at least don't find it a limiting factor in how they use their radios. Making a decision to go narrow band for GMRS would be an easy one I suspect for the FCC. On the engineering side of things it's rather a screwy situation where you have two different radio services assigned the same spectrum but with different technical specifications for bandwidth. If the goal was really to allow the two to interoperate the FCC screwed it up. Having one station on frequency running wide band and another running narrow band results in some annoying messing around with the volume control. It's either to loud or too soft depending on who is doing the RX'ing and the TX'ing. By the way this happens with DMR when people don't get their audio levels set right. One minute i can hardly hear one station and the other station blows be out of the chair.
  3. I read from time to time proposals to switch GMRS from normal FM to narrow band FM, 2.5KHz deviation, and the arguments for and against it including repeater owners. One of the questions that seems to get little attention is just how prevalent are narrow band FM capable radios out there that are in use? Any legitimate proposal to go narrow band has to address this question. I use several that can do both normal FM and narrow band FM, primarily Kenwoods like the TK-370G, TK-3170, TK-3140 to mention a few. The other point is how many of the current offerings from the likes of Midland, Btech and others that can do both or just narrow band like Midland that gets often mentioned? The point I want to get to is if the majority of radios currently, or at some point in the future, are just narrow band, because that's what people buy whether they know it or not, could be the tipping point where the FCC says GMRS is going narrow band. If most radios at that point are narrow band the disruption for the majority of users would be small so the FCC isn't going to worry so much about the small number of wide band radios out there. The FCC sort of did this with the combo FRS/GMRS radios where almost nobody was getting a license to use the GMRS channels. So they just changed the rules to reflect how the radios were really getting used. They didn't seem to worry much how this impacted GMRS users at the time.
  4. Good luck taking the Tech Class license exam when they start testing again. Welcome to the group. GMRS is a lot of fun.
  5. The rules were changed in 2017 and became effective in 2018 for all of the Part 95 services. All previous combo FRS/GMRS radios are now classified as FRS radios. https://www.govinfo.gov/content/pkg/FR-2017-08-29/pdf/2017-17395.pdf This site has a good summary of the new frequency and power limits. https://en.wikipedia.org/wiki/General_Mobile_Radio_Service The Baofeng UV5R, and variants, don't have the required Part 95 certification from the FCC and thus are technically illegal to use for GMRS. However people use them as such since they're cheap. Is the FCC busting people for using them? Maybe not, but you are playing a game of twisting the dragon's tail so if you get flamed you had fair warning.
  6. I would second that suggestion, Lithium battery. Specifically I would recommend a LiFePO4, LFP, battery. They have the safest chemistry out of the common Lithium battery types, light and reasonably high energy density. One other advantage to LFP batteries is the terminal voltage. At full charge they are around 13.3 or so VDC, a very good match to most mobile equipment that expects 13.8 VDC. The battery has a very flat voltage verses discharge curve so when the terminal voltage drops to 12.8 VDC the battery is almost completely discharged, like around 80 to 90 percent of the rated capacity is used. Don't try this with a lead acid battery. I've also found they have a very low self discharge rate. You can charge them up and let them sit for months and the terminal voltage hardly drops. For an Ecom application this would be an advantage. I've wreck enough Gel-Cell lead-acid batteries over the years I won't buy them anymore if the equipment can use the LFP type. Lead acid batteries don't like sitting around unless they have a trickle charger attached and don't let them sit around at less than full change, they will sulfate the plates. Neither of these conditions hurt LFP batteries. As a matter of fact one recommendation for long term storage of LFP batteries is to discharge them to around 50-80 percent of capacity, they can stay that way for months to a year or more this way without damage. While LFP batteries are much more expensive than the common lead acid type once you ruin a few lead acid batteries you'll get sick of replacing them and the cost adds up. I've had good luck with the following company for LFP batteries. https://www.bioennopower.com/collections/12v-series-lifepo4-batteries If you want to use a solar panel to recharge the battery a small MPPT controller designed specifically for LFP batteries is required. I have several from this company. https://sunforgellc.com/genasun/ I have a couple of the GV5 charge controllers, a good match for a 50 watt solar panel. For solar panels I got some from this company. https://www.renogy.com/products/solar-panels/ I have a couple of their 50 watt mono and 1 of their 30 watt mono panels. The build quality is good and they do guarantee them. On solar panels from my experience don't expect to get more than around 70 to 75 percent of the panel rating, which is derived under lab conditions, which you won't get in the field.
  7. Plugging in the height numbers into this online calculator: http://www.hamuniverse.com/lineofsightcalculator.html shows the difference in range is around 0.5 miles, distance to the horizon, more at the higher elevation. If you were located in an area that was flat its not much of a change. However you're in a bit of a depression so anything you can do to get the antenna higher will be beneficial and a reasonable trade off for a bit more coax loss. At some point you'll likely go for an antenna with some gain which will make up for the extra 1db of coax loss.
  8. I would think very carefully about doing this. Besides going to aluminum to save weight the sheet metal gauge is likely reduced too. With an NMO mount there isn't that much metal area to resist the bending moment of the antenna. I've read more than one account where the roof was damaged, roof area bent or the mount just plain ripped out, when the antenna hit a small tree branch or driving at highway speeds. At least with a magnet mount it will just knock it off the roof most likely with little to no damaged being caused. If you do go with a NMO mount research first for a good way to reinforce the roof are around it before doing the install. Many mobile antennas are fairly stiff and don't give much if they are flexed so an antenna strike goes straight to the mount. Some antennas are available with a spring located at the antenna base. These will reduce the chance your vehicle roof and or antenna will suffer damage from a low tree branch strike or other low obstruction contact.
  9. You want to look at something like the following: https://transition.fcc.gov/bureaus/oet/info/documents/bulletins/oet65/oet65b.pdf https://www.osha.gov/SLTC/radiofrequencyradiation/evaluation.html
  10. That might be a good thing, no fires and little criminal activity. 8-) I hear some interesting stuff every once in a while by monitoring the local mall security frequencies. A lot of them are still on analog narrow band FM with their UHF radios. Some have switched to DMR, P25 or NXDN. It gets better around XMAS. I've heard about hookers by the mall doors drumming up business, chasing shoplifters through the parking lot, fights in the food court you get the idea. A couple of times I heard them kick the local TV news crews off the property if they didn't get prior permission. Once the parking lot patrol spotted a couple doing their thing in a car. The mall security supervisor told the mobile security dude don't bother them.
  11. There are various web sites where you can look up this kind of info. One example is below. https://www.radioreference.com/apps/db/ In the programing mode, I assume one could find the frequencies of government channels like the park service or local police channels. Some may be listen only. Does anyone know how to find out what frequencies are used?
  12. If the repeater is listed as "open" that would be true. If it isn't then you do need to ask first. Ignoring the argument about the repeater being private property is the one about identification. As along as the owner, and their immediate family, use the repeater it will be properly identified every time a family member uses it and ID's per the FCC rules since everyone is using the same call sign. That may not be the case when others are allowed to use it. For instant if a simple controller is used with no builtin ID function. There are a number of cheap repeater controllers out there that do not have an ID function. A lot of these get sold where everything from a couple of handheld radios to high power mobile radios are used with them along with cheap Chinese duplexers to build a repeater. https://radio-tone.com/product/rt-crc1-repater-controller-full-duplex/ https://www.surecom.com.hk/surecom01_product.php?id=114919 If the repeater owner allows users outside of his immediate family to use the machine it needs to ID with the owner's call sign. This by the way is the same problem with Ham full duplex cross band repeaters, getting the machine's transmitter to ID when relaying the signal back to the owner's radio. So if you don't ask first you have no idea how the repeater is setup. The owner may not want people to use it since it lacks the ability to self identify and if the owner allows others to use it they could end up with a problem with the FCC.
  13. Using an old computer switching power supply likely won't work. First they are electrically noisy and will kill your receiver sensitivity. Second the designs use one of the low voltage outputs for regulation, 5 VDC - 3.3 VDC - ???, while the rest float around a bit. If the regulated output isn't loaded down enough it may not even start. We use a number of off the shelf switching power supplies where I work for some industrial controls. I have one right now in my office loaded down with a fat power resistor on the 5 VDC rail just to get the thing to turn on so I can use the other outputs for testing a project. About using it to charge a lead acid battery may not work well, if at all, since the high voltage outputs are a "nominal" 12 VDC on the computer power supply. You need around 13.5 VDC to 13.8 VDC to charge a "12 VDC" lead acid battery. Then there is the different charge stages to keep from damaging the battery, bulk - absorption - float, which is normally done by a smart charger. There is a bit of a difference between liquid filled, gell cell and AGM lead acid types on the charge and float voltages to content with.
  14. Nope. You’re never too old to try. It’s only complex if you really want to drill down into the technical details. Fortunately you don’t really need to in order to get licensed. The whole idea with licensing is to understand the rules, avoid causing interference and not hurt yourself or someone else. The learning comes at your own pace once you’re licensed and where your interests take you.
  15. I was doing some searching for anybody that may have tried the idea and stumbled across this gem. Got me a bit interested in the idea. https://az276019.vo.msecnd.net/valmontstaging/vsna-resources/microflect-passive-repeater-catalog.pdf?sfvrsn=6 While not exactly a water tower the idea is along the same direction, a passive reflector repeater.
  16. Maybe. It would be like reflecting a light beam off a mirror. It all depends on where the two antennas are located relative to the water tower. I know this could work because years ago I was talking to my brother on the Ham 70cm band which is just below the frequencies used by GMRS. He lived several miles from the airport. When a plane was at just the right point and orientation his signal jumped from an S0/S1 to over S9 for several seconds. He was using a base antenna and all I had was a simple magnet mount about 10 miles away. As a matter of fact back in WWII some of the early radars ran around 150 MHz, some used up to 300 MHz, and used a flat reflector with a number of dipole antennas mounted in front in such a way to get a directional beam to bounce off aircraft. https://en.wikipedia.org/wiki/Mammut_radar That was before Britain invented the cavity magnetron. https://spectrum.ieee.org/tech-history/dawn-of-electronics/from-world-war-ii-radar-to-microwave-popcorn-the-cavity-magnetron-was-there Other Hams bounce signals off the ionized trails left by meteors as they enter the Earth's atmosphere. It's called meter scatter.
  17. You can look at this radio. It is currently being sold by Kenwood. You can find them on eBay for a decent price. The link below is for just one example. https://www.ebay.com/itm/Kenwood-TK-3170-UHF-HH-Radio-DTMF-Keypad-Battery-Charger-Free-Programming/153889511911?ssPageName=STRK%3AMEBIDX%3AIT&_trksid=p2060353.m1438.l2649 As mentioned by others be sure you get a battery pack, charger and the antenna for it. You can find the programming software and cable online as well. If you buy a used one make sure it is a "Type 1" radio. Also watch out for people selling the European versions, you really don't want one of those since they don't have the FCC certification and requires a hard to find version of the programming software. On UHF most commercial radios cover different sections of the band. You want a radio that covers the 462 MHz to 467 MHz range. Also if you ever plan on getting your Ham License, the Tech Class is easy to get, this radio will also program down to 440 MHz, the normal Ham 70cm band runs from 430 MHz to 450 MHz, even if the spec's don't mention it. The section from 440 MHz to 450 MHz is where most of the Ham simplex operations and repeaters are located. This way you can have a Ham Band UHF and GMRS radio all in one. https://www.kenwood.com/usa/com/lmr/tk-2170_3170/ (Kenwood product page) https://www.ameradio.com/doc/Kenwood_TK-2170_TK-3170.pdf (Brochure) It has the required FCC Part 95A certification so there is no question if it's legal to use for GMRS. https://fccid.io/ALH34713110 (FCC info) I would look for a good commercial quality radio before looking at the cheaper Chinese type radios. Generally the commercial quality radios typically have much better receivers, more selective and don't loose sensitivity in strong RF environments like near large radio and TV stations. You get what you pay for. Oh, congratulations on getting your GMRS license! 8-)
  18. Yup. I have some friends that have either the Ham Tech or GMRS license and are looking at getting the other one. For the $70 and good or 10 years why not get the GMRS license IMHO.
  19. I think you have two things going on here. 1. The connector you installed, PL-259, is not a constant impedance type like the type "N" which will contribute to the higher SWR reading. The connectors calculate out, based on some dimensions on a few I've looked at, of around 25 to 40 ohms. It also depends on what the dialectic material used happens to be as well. The length, connector, of the miss match section also matters but in this case its rather small. This results in an impedance "bump" and a cause for some reflected power. If the radio uses an SO-259 socket there isn't much you can do about that. 2. When you cut the cable length from 100 feet to 35 feet you reduced the losses in the cable. However that applies to not only the forward power but also the reflected power. The formula for calculating SWR based on the power reading is: SWR = (1 + sqrt(Pref / Pfwd)) / (1 - sqrt(Pref / Pfwd)) Where: sqrt() - square root function Pfwd - Forward power Pref - Reflected power How this works to increase the SWR reading as measured at the radio end of the cable is as follows. With lower forward losses the reflected power from any antenna mismatch will be higher because the power to the antenna has increased. Additionally the reflected power is attenuated less as well. Both work to increase the ratio (Pref / Pfwd) in the above formula. Remember you're measuring the forward power at the radio end and that hasn't changed. Thus the numerator becomes larger while the denominator smaller in the above formula. The final result is the number calculated becomes larger, the SWR. I suspect the cable length change has more to do with the increase in SWR than the connector in this case. So as others have pointed out most radios work OK with an SWR up to 2:1, at least that's what I've seen in the spec's for the ones I looked at, without issues. An SWR around 1.5:1 or so is fine. You won't gain much by trying to lower it.
  20. I scrolled down the page at the link above and the spec's given were: ------------------------------------------------------------------------------------------- Technical Specs: License Free FRS Radio 462 - 467 MHz Exceptional conditions: Approx 20 Miles range Everyday use: Approx 3.2 Miles range Rugged city use: 50 floor penetration One-piece back clip 9-level noise reduction 80 decibel speaker output 16 Memory Channels 8,000 mAh internal battery Type-C fast charging Only 1.5CM thick (as thin as an iPhoneX) Under 5oz weight 15 day standby LED dot matrix display Headphone charging interface Transmitter Output Power: 2W/0.5W Modulation: FM (F3E) Max.Frequency Deviation: ≤5KHz Sparious Radiation: ≤7.5μW Receiver Sensitivity: 0.16μV(12dB SINAD) Audio Power: ≥300mW Audio Distortion: 80 decibel speaker output Receiving Current: <300mA Standby Current: <200mA Emission Current: <1800mA Audio Distortion: <5% Intermodulation: >60dB Max Frequency Deviation: <5KHz Supply Power: DC3.7V CTCSS/DCS: The transceiver has 50 CTCSS and 208 DCS, also non-standard subaudio can be programmed ---------------------------------------------------------------------------------------------------------------------------------------------------- To me it just looks like a cheap DSP based "radio on a chip" type hand-held. This is common in the "Baofeng" type Chinese radios. They use the RDA1846, or a derivative of it. You can get the datasheet and programming guide for the chip here: https://github.com/phishman/RDA1846/tree/master/Datasheets I would like to see the FCC ID, which it should have to be sold in the US. From the FCC web site can you see what parts the radio has certification for by looking at the grant.
  21. The site below has some good info on various Chinese radios. http://www.miklor.com/ Your specific radio may not be there but a closely related one likely is.
  22. You should contact the vendor and have them check it out. Some antivirus software will flag good software as having a virus. We have an in-house written utility to load a calibration-configuration file to a custom designed microprocessor based board where I work. The IT department used Webroot and it kept erasing the utility exe file after flagging it as virus infected. Really frustrating. Had to get IT to put that file in an exclude list to keep from getting erased every time I tried to install it. 8-/
  23. If you want the better coax, hard-line, its going to cost you. The site below does sell 1/2" and 7/8" hard-line. It seems they are able to install the connectors too. I'm sure there are other places you can get the cable, likely at around the same cost. http://www.davisrf.com/heliax.php
  24. If you’re going to splice in jumpers be sure to use a constant impedance connector like type “ N”. Every connector has a small insertion loss. Usually a fraction of a db for good quality ones. The small power loss shouldn’t be very noticeable. Also be VERY sure to weather proof the splice points if outside. It’s also a good idea to do the same at the antenna base where the cable connects.
  25. Some items they do. I have actually contacted vendors in the past if they are going to offer a discount on an item I wanted. It might not be much, around 5 percent, but on a $500 radio for example it adds up. Plus you may save the shipping costs too.
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