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Lscott

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Everything posted by Lscott

  1. I have an FT-817 and the included 6M antenna sucks. You realize for a 1/4 wave 6M antenna the required ground plane radials need to be about 60 inches long. The body of the radio is nowhere even close to that. Now holding the radio, well now your whole body might function as a sort of ground plane but the vertical element is still a crappy very short loaded helical design with high losses. Does the antenna radiate, yeah, but poorly. There is a reason why you don't see a bunch of HT's with the 6M band included. Most 6M activity is during band openings and then it's typically on sideband anyway, not FM. I just check "repeaterbook.com" and there are a total of just 15 6M repeaters listed for the entire state of Michigan for example, it's not that popular for FM, at least around here.
  2. Those radios use an RJ-45 style plug I believe. I would check the connector that plugs into the radio. All the contact fingers should be clean. You can try to wipe the contacts down with alcohol, the programming cable, and use a Q-tip to do the socket in the radio. Sometimes gently bending the contact fingers out a tiny bit helps if you can get to them.
  3. The antenna efficiency of an rubber duck 6M antenna on an HT is going to be really poor. Unless you plan on using an external 1/4 wave antenna with a ground plane it’s more of a marketing gimmick. The 2M VHF rubber duck antennas I’ve seen where it was stated as a negative 5 db gain in some cases too. A 1/4 wave UHF antenna for Ham 70cm and GMRS is about 6 inches long. That’s small enough to fit on an HT where the body of the radio is just about big enough to make a reasonable ground plane. Even better when holding it. I made a 1/4 ground plane antenna, with radials, using some heavy buss wire and a PCB BNC socket. The measured 2:1 bandwidth covered almost the 430 to 470 MHz range with a nearly perfect match around 448MHz. Good enough for Ham and GMRS. I used the antenna zip-tied to a baseball cap while walking around the Dayton Hamvention a couple of years. That let me hang the radio on the belt using a short jumper cable and speaker mic. I only needed about 1 watt for good communications with the antenna up in the clear. I might have looked like a nerd but I wanted something that worked, cheap and simple to build.
  4. IF range was only determined by power then your range varies by the square root of the two powers. For example comparing 45 watts to 15 watts you get: sqrt(45/15) = 1.73 In other words your range should increase by a factor of 1.73 going to 45 watts verses 15 watts. There are other factors that will conspire to reduce this. You need to pay attention to the cable between the radio and the antenna mount. The RG-58 cable that’s typical used is fairly lossy at UHF. The loss can be compensated for by using a gain antenna. High gain antennas have their issues so they might not be a good fit for your application. If you mainly operate in very hilly or mountainous terrain a simple 1/4 wave antenna likely will work better. For flat open terrain a high gain antenna performs well. There are a few antennas that require no ground plane allowing more options on mounting locations. Some of the other forum members likely have some good recommendations for this type of antenna. A few people even keep more that one type in the vehicle and swap them out depending on operating requirements. Maybe a high gain one for use in a convoy while travailing on a highway then a short 1/4 wave for off road use.
  5. Yup. The D74A is a nice radio. I also got mine from HRO and had them do the MARS/CAP mod for the same reason. The only negative is the battery pack capacity, it doesn’t last that long.
  6. https://en.wikipedia.org/wiki/Superheterodyne_receiver
  7. Yeah, check it out for the specific radio you're looking at buying. With all the features radios have now it's easy to overlook a detail like this and end up with something you can't use and paid a premium to get it. Some of the Ham radios include a feature called "APRS". You can get the details of what that might do for you here: http://www.aprs.org/
  8. The rules are written the way they are because the underlying assumption is the user is a non technical person who has no idea what the difference is between Hertz and Hurts. The rules are designed to prevent interference to other services regardless of how a user manipulates the radio’s controls, either deliberately or by accident. Hams are held to a higher technical standard, and assumed to know where the bands are located frequency wise. There are few out there that would be challenged using two soup cans connected by a string, it’s not a guarantee somebody is competent just because they have a Ham license. It’s not a perfect world.
  9. A number of people recommend the FT-60R. About the only thing it doesn't have is GPS. A number of radios that have GPS it ONLY works in the digital modes. So if the others in your party don't have similar radios it's sort of useless. Plus the GPS function simply TX's position messages that are displayed on a compatible radio. Again if the others don't have such a radio, that can display the text messages, the feature isn't going to be useful. Before spending the money you need to check into this very carefully or you'll end up with a nice radio with GPS nobody else can take advantage of on the air. https://www.yaesu.com/indexVS.cfm?cmd=DisplayProducts&encProdID=6EC43B29CEF0EC2B4E19BB7371688B7F Brochure. https://www.radiotrans.com/archivos/catalogo/FT-60_EN.pdf On line sellers. https://www.hamradio.com/detail.cfm?pid=H0-007323 https://www.theantennafarm.com/catalog/index.php?main_page=product_info&cPath=115&products_id=432 For the RX/TX frequency expansion. If done by HRO they will warranty the radio. https://www.hamradio.com/detail.cfm?pid=71-002354 https://www.theantennafarm.com/catalog/index.php?main_page=product_info&products_id=417
  10. I think gman1971 can answer that. He's pretty much the Motorola expert on the forum. He's help me out with some issues with a few XPR6550's I recently got.
  11. Per the FCC rules they state the following: https://www.ecfr.gov/current/title-47/chapter-I/subchapter-D/part-95 "§ 95.1761 GMRS transmitter certification. ..... No GMRS transmitter will be certified for use in the GMRS if it is equipped with the capabilities to operate in services that do not require equipment certification, such as the Amateur Radio Service. All frequency determining circuitry (including crystals) and programming controls in each GMRS transmitter must be internal to the transmitter and must not be accessible from the exterior of the transmitter operating panel or from the exterior of the transmitter enclosure. " Yes there are radios that "allow" FPP, front panel programming, but with conditions. Many require a deliberate hardware modification, typical diode, resistor or solder shunt removable, and enabling in the radio's programming software. Others require entering a "secret code" to switch operating modes, typical of the Chinese radios. So, as long as the radio is configured to comply with 95.1761 it is operating under GMRS rules it's legal. The moment this is violated you're not compliant so the transmitter is now operating with illegal functionality and loses it's certification, even if it isn't being used. Of course it can be switched back, in which case the radio again would be in compliance, and the certification once again applies if it had it to begin with. My Kenwood commercial radios can be modified for FPP, needs the hardware mod and the feature enabled in the software. There is a warning that radios MUST NOT be returned to the end user(s) with FPP feature enabled, so it's disabled in the software with the modified code plug written to the radio. Of course if the radio is ONLY going to be used on the Ham bands it's not a problem. The problem revolves around the last sentence quoted above. Some feel just because the feature is there then there is no issue with enabling it. The FCC is clear that's not the case. There is no mention that one must be using the feature, the mere fact it's "possible" to access through some action(s) performed by the user is enough to void the certification. This includes changing the "mode" though any means accessible by the user external to the radio, such as pressing a sequence of buttons etc. during power up or any other time. There is a VERY fine line with switching modes through a sequence of button presses. There is a reason why it's NOT documented, at least for anything an end user gets to read. The user isn't supposed to even know about it. This could be considered a violation of the above section of the FCC rules. If there is any debate it would be over this point alone. Everything else is fairly clear cut IMHO.
  12. Don't forget about the effect from the apartment's building materials. If you have cement walls there is likely rebar in it, wood and brick may have foil backed isolation in the walls, metal tint on the windows, high lead content glass, metal blinds etc. Some newer construction has sheet metal wall studs in place of the old wood ones as another item. There is a pile of construction material that can screw with a UHF signal. The building where I work has two of the above, poured concrete walls with a loose metal mesh and the office walls have metal studs. Needless to say the reception is rather poor for weak signals for anything other than a signal a mile or so away, and trying to TX is worse.
  13. Oh, if anybody is interested in that book I mention in a prior post you can download a PDF copy from here: https://dokumen.pub/qdownload/tapr-spread-spectrum-update-tales-from-the-rebel-alliance-9780964470750-0964470756.html
  14. We don't have to agree, but the discussion was beneficial for those that choose to just sit back and read. If it got people to think about other points then it served it's purpose. 8-)
  15. Frequency hopping IS a form of spread spectrum transmission. Regardless of what algorithm is used to determine the next frequency hop some communication needs to take place between the two radios so they remain synchronized. Otherwise the RX radio would need to monitor several frequencies and try to "guess" where in a fixed sequence the TX radio is currently. I did read about some radios used during Vietnam that used encryption, and I think some form of FHSS, and wasn't well received. The chief complaint was the delay in decoding the audio and for the radio's to sync up. The second(s) delay was critical under battle conditions where rapid communication was necessary. https://en.wikipedia.org/wiki/AN/PRC-77_Portable_Transceiver Types of spread spectrum modulation. https://en.wikipedia.org/wiki/Spread_spectrum
  16. Since I don't really need the radios for critical communications I can afford to wait for a good deal. That's part of the fun collecting them, finding a good deal. The second part is trying to discover where the radio came from originally. I managed to find this out on just a few. The best one came from "Nine Mile Point Nuclear Station" out east. I think another poster knew about it and commented they replaced all their analog radios with digital. Nice confirmation of what I figured out from the names in the memory tag fields and frequencies programmed in to the radio.
  17. It's different because it happens under automatic control and is an intrinsic feature of the transmitter's frequency and modulation circuits, and not subject to operator control on a per frequency hop, nor even what the hop pattern that's implement, fixed or pseudorandom.
  18. That's some useful advice about simplex. That's what I was looking for. I have the Kenwood UHF TK-5320 radio, 400 to 470 band split, and use KPG-112D to program it. I would like to find the VHF TK-5220 if I can find a good deal on one in good condition. https://comms.kenwood.com/common/pdf/download/TK-5220_5320_Specsheet.pdf I do have a used NX-340(U), no display HT, I purchased and a used NX-820HG mobile I was gifted by a buddy that has no use for digital comm's. Both are the 400 to 470 band split I believe. I also have the software to program them. https://pdfs.kenwoodproducts.com/54/NX-240V&340UBrochure.pdf https://comms.kenwood.com/common/pdf/download/10_NX-720HG&820HGBrochure.pdf I would like to get an HT with a display. The older NX-200/300 look nice. The newer NX-205G/305G look good too but I only have the HPG-111D V4.7 which doesn't show the 205G/305G types as models it can program. I'm trying to get my hands on V5.21 of the software, which I hope does do the newer models. So far no luck with the zero cost option. Until I can get the software that handles them I'm not going to purchase any of the newer models. I also picked up a new in the box UHF amp, BTECH U25D, at a swap for a good price, about half of new, that should work with analog and digital modes. Good to boost an HT running mobile or as a base. https://baofengtech.com/product/amp-u25d/ https://www.miklor.com/COM/Review_DMR-Amps.php
  19. The permitted emission types for GMRS are listed here: https://www.law.cornell.edu/cfr/text/47/95.1771 The FCC emission designations are listed here: https://www.electronics-notes.com/articles/radio/modulation/itu-radio-emission-designators.php And yes the FCC does in fact use the ITU emission designations as do many countries. Note under "Character 5 details of multiplexing" letter indicator "C". This does not appear in any of the permitted emission designations for GMRS. Depending on which source you consult FHSS, frequency hopping spread spectrum, could also be designated as an "X" in the emission type, a type not covered by any of the other types. This also does not appear in the permitted emission designations for GMRS either. Then the very name "spread spectrum" of course implies the signal is spread out over a range of frequencies. The permitted bandwidths on GMRS are only 20Khz and 12.5KHz. Having a signal hopping around many times per second would be effectively a wide band signal exceeding the permitted bandwidth. Again, IMHO, I think this would exclude the use of FHSS on GMRS. If somebody has a different opinion that's what the form is here for, a friendly discussion and debate.
  20. It wasn’t clear so I was questioning it. I would have to go and double check on this point but even on the Ham bands the FCC specified the spreading code was allowed at one time. That might have changed over the years. https://www.law.cornell.edu/cfr/text/47/97.311 https://files.tapr.org/tech_docs/Ham_Ethernet_GBPPR.pdf I have a book on my shelf written by TAPR, Tucson Amateur Packet Radio Corporation, with the title of “Spread Spectrum Update - tales from the rebel alliance”. The book covers spread spectrum technologies and some of the basic math behind it. This also includes issues with interference etc. The book was published in 1998 so a few things have likely changed since then. It’s primarily aimed towards Ham radio of course.
  21. Sooner or later I should add a cheap Fusion digital radio to my collection. The GM club operates a wide area coverage repeater from the top of the now called GM headquarters building in downtown Detroit. Most people still call it the RenCen. http://www.gmarc.org/wp/wp-content/uploads/2020/05/RenCen-repeater-qsl-compressed.jpg
  22. I just got a 7% off offer on a NX-200. Not biting on this. The seller has a huge number of radios being sold in other ads, different models. Sooner or later he’ll get tired of the inventory not moving. Out of 25 units of the above radio he’s only sold 2 in the past week. I’ll wait for a better deal. He won’t lower the price on single units per a response to a “best offer” option in his ad. Oh well he can keep them. I just buy radios as a hobby to add to my growing collection, I really don’t have a burning urgent need for them. I can afford to pass up ads if I don’t like the price or the seller doesn’t want to deal.
  23. The questions I have are first is this even legal on GMRS? Second with the small number of channels available just how effective would it even be? I don't think you would want to be doing this on the repeater input channels. The low power FRS ones are sort of useless which leaves just channels 1 to 7 to use. The frequency hopping radios I've heard about are digital, and digital voice is not allowed on GMRS anyway.
  24. Yeah, simplex around here is sort of dead too. I very infrequently hear any CQ calls on 146.52, even when mobile, my primary operations. I try to respond to the 52 calls when mobile due to the low activity I observe. I have radios for D-Star, DMR, P25 and NXDN so far. I'm was wondering what to use for simplex operations. Seems like just about everyone uses repeaters since they are typically linked. I wanted to include some simplex channels in the various radios I have to supplement the repeater channels. That leads back to the thread's topic, pros and cons. Talk groups and networks. I know on DMR that TG-99 is the talk group used for simplex operation, but what about the other modes? This gets into the area where I've found separate networks, even for the same digital modes, where the talk groups are not entirely the same, however there has been progress in that area. Then there are the bridging issues. This all seems to be a very unnecessary complication. Here are some examples. https://brandmeister.network/ https://dmr-marc.net/ https://w8cmn.net/mi5-sites-talkgroups/ http://www.nxdninfo.com/ https://w8cmn.net/p25/ Then the last point is usually you get just one digital mode per radio model or manufacture. I did hear about a couple of people that hacked the MD380 hardware where there is the possibility of getting a multi-mode digital radio without the astronomical cost from manufactures like Kenwood and their NX-5000 series multi mode radios along with the licensing crap that goes with it. I read somewhere the programming software for them is a POS. That's another problem area. Some manufactures CPS, customer programming software, is rather easy to use and or well organized with a good help system. One of the very popular Chinese DMR radios their CPS sucks. It's buggy and the built in help is almost worthless since there is basically "maybe" a line or two describing a feature. The other choice is looking at a bunch of YouTube videos hoping the area one has an interest in gets covered. Other's like Kenwood keep their training materials locked up behind a "dealer" login portal. I suppose that's done to support their dealer network, they want to discourage customers from programming their own radios. and funnel business to the dealers. A personal observation it seems most digital voice modes are mostly used on UHF. I'm assuming it's because you can find good commercial gear for UHF far easier, and cheaper, that on VHF. Second there is just simply more spectrum where people can spread out. I've been looking for some select Kenwood VHF analog/digital radios for a while. The few I see on the major auction site usually are much more expensive than the UHF model, if you can find one at all. I'm looking at an NX-200-K2 at the moment if I can win the auction without paying a fortune for the radio to add to my "collection." Around the Detroit area, where I'm at, there is little P25 activity and there is only one NXDN repeater listed for the whole state, and I don't think it's even linked into a network either.
  25. I know some operators get very annoyed when monitoring their favorite FM simplex frequencies when a digital station pops on on one. That's lead to digital voice operators to use "suggested" frequencies reserved just for digital voice modes. What are the typical frequencies used for digital voice modes when using simplex? I found several recommendations for 2m and 70cm. It seems like there are only a few suggested frequencies. Since there are several digital voice modes used, (D-Star)(DMR)(Fusion)(P25)(NXDN) and some others, are separate simplex channels used for each or all lumped together?
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