Lscott

Yup. The question was already answered. If there is going to be a standard highway/road channel, where one has been proposed and used for a while, we should stick with it. Trying to establish another one just confuses people and likely guarantees nether get used much. Unless there is a very good reason to change it I don’t see the point trying to establish something different.

https://forums.mygmrs.com/topic/1847-any-suggestions-for-a-highway-channel/

The location where you use the radio can make a huge difference in your reception. Try moving around and even try outside.

Looks like the default settings when programming in a new memory channel. I’ve seen this on some of my other radio’s programming software.

You check the squelch settings?

To change things up a bit, I would like to get some info on talk groups. At one point “RepeaterBook.com” would show which talk groups are accessible through a given repeater. Lately I don’t see this listed anymore on the details page for a given repeater. I can find lists of talk groups, seems the various modes are tending to use the same group ID’s for the same functionality and locations, at least for DMR and P25 I’ve looked at so far. But that doesn’t help if the repeater doesn’t support all of them. I’ve also seen recommendations to use my DMR ID, CCS7, for my P25 ID. For example I’m building a code plug for a P25 radio, TK-5320, and I wanted to test the audio by using the “Parrot” talk group on a local repeater. Looks like I can activate the repeater but nothing else happens. I don’t know if it’s my problem or the repeater doesn’t support that function/talk group.

The brass rod will work just fine. Being rather stiff it won’t bend out of shape from handling the antenna, that’s the advantage. One other thing, the larger diameter wire or rod tends to increase the bandwidth too. That means you might get away with an antenna the works over the range of two services, like Ham 70cm and GMRS, or Ham 2M and MURS. Manufactures typically spec the usable bandwidth of their antennas at the 1.5:1 SWR points. Practically most radios are OK up to a 2:1 SWR. The higher the SWR of course results in a larger usable bandwidth. Go ahead build some antennas, experiment, do some reading and ask questions. It’s a great way to learn, and you can end up with a usable design that you hand crafted yourself!

You have some points. The dual channel direct mode likely works well enough otherwise the more established name brand manufacturers wouldn’t be offering it. I have a Kenwood TK-D340U that has it. I haven’t really played with the radio, need another radio with the same feature to test it out. At least a model and manufacturer one can reasonably expect the radio to be designed right. https://comms.kenwood.com/common/pdf/download/DMR_TK-D240V_D340U_K_letter_1124.pdf The switching between TX and RX should be very fast using TDMA since the frequency doesn’t need to change, unlike FDMA modes. If the frequency needs to change then you have the pull in lock time for a PLL type frequency synthesizer. A DDS doesn’t have that problem, but still has to be programed through the micro which does take time, maybe not as long as a PLL design. If there is a big delay between switching TX/RX I suspect it’s due to other issues unrelated to the electronic power switching.

If it isn't part of the standard it could be at some future point in time. The ability to do single frequency repeater operations is just to good of an idea to ignore. Designers haven't used, mostly, relay switch for low to medium RF power in years. Looking at just about every HT for example they use PIN diodes to do the RF switching, which can be done much faster than any mechanical relay could do. https://electronics.stackexchange.com/questions/166579/pin-diode-t-r-switch-for-use-with-rf-power-amplifier https://www.richardsonrfpd.com/docs/rfpd/High_Pwr_Sw_Des_Guide.pdf The rapid switching required due to the used of TDMA shouldn't be a problem. Also I think the Anytone D575UV mobile has the single frequency repeater function in the firmware. https://www.youtube.com/watch?v=p2mnsOla5fE https://www.youtube.com/watch?v=lhX1_mEpJq0 Also with DMR you have DCDM, dual channel direct mode. This is where you can have two simultaneous voice communications occurring on the same frequency without the requirement of a repeater to sync the two time slots. the radios will figure it out on their own. Examples. https://www.mototrbo.sk/en/mototrbo-systems/simple-connection-direct-mode-gb https://ecfsapi.fcc.gov/file/6512562680.pdf https://mra-raycom.com/wp-content/uploads/simple-file-list/Specifications/DMR-Product-Overview.pdf

The charger is for mobile use. I have several of these. They work with multiple Kenwood Ham HT’s. I use this with a fanny pack carrying a lithium iron phosphate pack cabled to a matching socket for extended run time. The radio I used for years, and the very first one I purchased new, when I first got licensed about 20 plus years ago was a Kenwood TH-G71A dual band. I still have it, serviced a couple of times over the years due to a failing volume control. I recently picked up a used one at a swap in very good condition for $45 as a “spare”. My original one I did the MARS/CAP mod on it years ago. The used one I got I left unmodified. I also have a collection of speaker mics, head sets etc. So far the best for walking around and monitoring is the “D-ring” ear speaker with the lapel PPT/mic combo. I use that when I’m out at the mall waking around with the TK-3170 hanging on the belt under a long loose fitting shirt to hide the radio. I run the cable up under the shirt. The only thing you see is the ear mounted speaker. Nobody even bothers to look or stare, including the mall security cop, who I monitor all the time. Likely think it’s just some kind of cellphone accessory.

I would think any digital mode that doesn’t use TDMA, like DMR, would work in a mix mode environment. I think FUSION uses FDMA as well as some less used modes like NXDN and P25 Phase 1 radios. Supposedly P25 Phase 2 will be TDMA, not FDMA. One thing that has me thinking about DMR is the ability to run a single frequency repeater, which doesn’t require any cavity filters. That’s only possible because of the dual time slot nature of the transmissions. You can run two independent voice communications on the same frequency, each using one of the two available time slots. One slot is used for the input to the repeater (RX) while the other time slot is used for the output (TX). Since the radio is never transmitting and receiving at the same time, only one time slot is active at any moment, the need for duplexer cavity filters is eliminated. That makes for a very easy repeater to setup. Set your operating frequency, connect to the antenna of your choice, switch on the single frequency repeater mode and let it rip.

I only got one with a speaker microphone, battery pack (the lower power 6VDC one), case for expendable batteries, antennas and charger. All for $15 with original documentation and box. The radio looked like it was treated well, minimal scuffs and scratches and seemed to work when he showed it to me. So far I haven’t done anything with it yet. It looked like such a good deal for the price I couldn’t resist. The guy was selling it because he went with a newer analog/digital radio and had no use for it any longer.

I know it’s not legal for Ham and GMRS. If I even got one I might sell it. The D878UV claims to use DES-256 encryption on DMR I believe, and is already built in to the radio’s firmware, nothing else to buy or license. On some of the analog Kenwood’s, that take optional voice scrambler option boards, require a few electrical mod’s to use them. Typical a resistor or few need to be removed. They are not just plug and play with a check mark in the CPS.

Slightly off topic. Has anybody any experience with Kenwood’s KWD-AE31K optional encryption board? Seems to be a high end one using AES or DES for their different model digital radios. https://csrc.nist.gov/csrc/media/projects/cryptographic-module-validation-program/documents/security-policies/140sp2200.pdf Some of my radios have a cover plate on the rear under the battery pack to install optional feature boards. Some of the boards available are various voice scramblers, trunking etc. I haven’t been lucky enough, so far, to buy a used radio where any option board was installed.

https://radiofreeq.wordpress.com/2013/07/15/3-3-3-radio-plan-for-shtf-communications/

If range was strictly limited by power the range would be reduced by sqareroot(Pout/Pin). So a 40% power loss would amount to a range of 77% of what you would get with zero power loss. For a 20% loss it is approximately 89% range from the zero loss case. https://www.phys.hawaii.edu/~anita/new/papers/militaryHandbook/one-way.PDF As you noted a 20% loss is only 2DB. Even a modest gain antenna would make make up for the loss. Depending on your operating characteristics it might not matter much unless you’re right at the fringe of making contact.

I see posts at times where people want a radio for “emergency” communications. That’s great. But if you don’t have a way to keep the radio on the air it’s useless. Various radio services are used, Ham Radio, MURS and GMRS/FRS. Since this is primarily a GMRS forum what plans and procedures have people implemented, such as frequencies, alternative power sources (solar, generators etc.) to keep their station on the air? Myself I have radios for all of the above. I also have a collection of solar panels, charge controllers and tend to use LiFePO4, LFP, battery packs. I hate Lead Acid batteries. I’ve ruined enough of them even with care. In addition I have a few battery eliminators when using the mobile or the big LFP battery packs. The LFP batteries you can charge and just about forget them on a shelf for a year or more and they still hold enough charge to power a radio for a significant time. Can’t do that with a Lead Acid type. For antennas I have one dual high gain on the Jeep that works for Ham, MURS, GMRS and another dual band I can deploy on a portable 20 foot push-up mast. I have additional mobile antennas with magnet mounts I can use too. Making a 1/4 wave antenna is dead simple. For GMRS the vertical element is only 6 inches tall. Used some 2M elements that screw into the magnet mounts and cut them down to the frequencies required. I did that for a 1.25M one since I have a few tri-band radios for Ham and didn’t have an antenna for the band. Some of the charging bases for my radios use up to 15 VDC, while the battery packs they charge never exceed a bit over 8 VDC. Running them on 12 to 14 VDC should work fine. A few of them I modified with Anderson Power Pole connectors to run off a vehicle electrical system or the LFP packs with the adapters I made. One set of radio models I have battery cases that will take various types of expendable batteries.

Somebody picked up two Motorola XTS-2500’s for a tad over $100. If they have battery packs, chargers, programming cables with software it was a super good deal. I don’t so I bid on the Kenwood radio, have the software, programming cable, battery packs with chargers for it. https://www.ebay.com/itm/2-MOTOROLA-XTS2500-III-UHF-380-470-MHz-P25-Digital-Two-Way-Radio-H46QDH9PW7BN-/165026697807?mkcid=16&mkevt=1&_trksid=p2349624.m2548.l6249&mkrid=711-127632-2357-0 https://www.ebay.com/itm/2-MOTOROLA-XTS2500-III-UHF-380-470-MHz-P25-Digital-Two-Way-Radio-H46QDH9PW7BN-/165026697807?_trksid=p2349526.m4383.l44720.c10&nordt=true&rt=nc&orig_cvip=true

This is the brochure I found. Go figure. https://www.motorolasolutions.com/content/dam/msi/images/vertex-standard/legacy-products/vx_924_specsheet_en.pdf Looks like they have more than one band split apparently, but the brochures don’t show them.

What do you use the VX-924 for? It has a listed band split of 66 MHz to 88 MHz. Unless you can get it to drop down to cover the 6M band, 50 MHz to 54 MHz I don’t know what else you could do with one in the US. I know the UK has a 4M band around 70 MHz so it would be useable there. There was some talk at one point about a 4M band here as well. Don’t know where that went.

Yup, you’re not alone. The TK-5320 has a used battery pack and charger base, but no antenna which I have plenty of anyway. I think I already have several battery packs that fit this radio I got with some of the other used radios I’ve purchased. The seller guarantees the radio is functional. I paid $110 for it on eBay, cheaper than just about any of the other P25 radios I saw.

I have so far, just for my commercial Kenwood radios, 14 different versions installed. Some the only difference is a different "market code", North American verses European models, that have different versions of the firmware too. Examples, I have the TK-3140K's and the TK-3140M's, different versions of the CPS required. And Even the code plugs are not interchangeable, the radios have different feature sets. Then there are the TK-3170K's and TK-3170E's, same CPS but the code plugs are different, again differences in feature sets. And for the Ham radios from Japanese and Chinese manufactures it's a big collection too. I ended up doing a spread sheet showing which model radios use which CPS to keep things straight for all my radios. Then there are the different battery packs and chargers....

I would like to thank everyone for the help! One thing I found with the programming software was the various settings for ID's talk groups etc. was set to use Hex number entry by default! Dah! I couldn't figure out right away why I couldn't enter some of the settings, my DMR ID has 7 digits, but the software allowed only 6. When I saw a note in the help file about a setting in the "Tools" menu to change the P25 section to use a different number format then I could make the entries. I have no idea if other radios and their software does both decimal and Hex number entries. New radio and a new learning curve. 8-/ Maybe my next radio will be a cheap HT with System Fusion. Right now I have radios for D-Star, DMR, NXDN and now P25 when it shows up. This is the nearest P25 repeater to me at the moment. Not many around MI, OH, IN or ILL. on 70cm. https://www.repeaterbook.com/repeaters/details.php?state_id=26&ID=276 Repeaterbook.com is great for looking up repeaters to use BTW. Also there is a free app for the iPhone at least.

I'm waiting to get my latest radio acquisition, a Kenwood TK-5320. Its a dual mode analog/P25 radio, from an auction at a good price. I got the 400 MHz to 470 MHz band split version, perfect for Ham Radio. https://pdfs.kenwoodproducts.com/18/TK-5220&5320Brochure.pdf I'm in the process of building a code plug for it using the KPG-112D V2.01 software. I have a few questions. 1. Is there any standard P25 simplex frequencies people use for P25? 2. Is a unique ID required to get on a networked P25 repeater? If so where do you get one assigned? I already have my DMR and NXDN ID's. 3. I see that talk groups are used like with DMR. Where are those listed? Are they the same as used for DMR?