Lscott

It wouldn't be a bad idea to program two sets of channels, one wide band and the other for narrow band. The radio has enough memory slots. Since you can legally talk to people using the cheap FRS radios, which are narrow band only, this would keep your audio from sounding way to loud and distorted to those users. One set would be labeled GMRS 1..GMRS 2 and so on as wide band. The second you can label FRS 1..FRS 2 etc. as narrow band.

I would still like to see which specific models were tested and the data you collected. That’s the relevant point. Is it just one particular model or the manufacturers whole product line that’s better or inferior to another’s. I suspect it’s just one standout model.

I haven’t used it much in a while. Likely would be looking at something from the major Japanese Ham gear manufacturers. I could go with a used commercial radio but those are almost always mono band. I would want at least a dual band.

Well that helps clear up the mystery a bit. I’m mainly interested in the older Kenwood radios. I’m going to guess that the problems are more with the newer NX-5300 series radios that claim they can do two out of three digital modes, P25 - NXDN - DMR, switchable by the user. I’m not interested in getting any of those simply due to the license key crap they implemented like Motorola has done with feature upgrades on their radios. I see more of these showing up on the used market, I assume for a reason. Some of the older Kenwood radios are damn hard to find, at least for a price that won’t bust a bank. The older NXDN radios aren’t too hard to find and for a reasonable price. I’ve picked up some of the NX-200’s and NX-300’s on eBay. https://comms.kenwood.com/common/pdf/download/301_NX200-300.pdf Now the P25 stuff is a different story. The few TK-5320’s and the TK-5220’s in particular are hard to find and expensive used. I’m still looking to bag a second TK-5220 if I can find one that the seller isn’t asking a stupid high price for it. I have a couple of the TK-5320’s now. https://comms.kenwood.com/common/pdf/download/TK-5220_5320_Specsheet.pdf I just picked up a NX-320K radio. I’m toying with the idea of trying to change the market code to make it a NX-320E. Those apparently can get a different firmware loaded to run dPMR digital voice mode. It’s almost unknown here in the US, this is far more common in Europe. I already have the specific radio programming package for that, KPG-161D. There is mention of the modification in the brochure. https://kenwoodme.com/wp-content/uploads/2018/03/03-NX-220_320-1.pdf This is a hobby for me, I’m not running a business so trying to squeeze every last db of performance out of a radio is not my top priority.

I was commenting about similar Kenwood radios for performance. The contrast between how DSP is implemented, DSP chip verses doing it in an FPGA, is a choice between performance verses cost. Designers have used FPGA when the required performance can’t be met with a DSP type processor. With an FPGA the “processing” can be done in parallel. With digital radios the important metric is BER, bit error rate, or how well the radio can recover the digital data. While the analog section might be superior if the DSP algorithms suck then that advantage disappears. Without access to the code there is no real way to know. https://www.electronics-notes.com/articles/radio/bit-error-rate-ber/testing-bert.php https://www.researchgate.net/profile/Steve-Russell-5/publication/265842942_DSP_Demodulation/links/541c7d540cf2218008c9d275/DSP-Demodulation.pdf?origin=publication_detail To clarify things a bit when you mention your ISOtee tests it would be beneficial to mention which models you tested. Simply claiming one manufacturers equipment is superior likely isn’t true for their complete range of products nor newer or older versions of the same model, or even between older verses newer models. Designers very often change designs and or critical parts that affect performance even if the model name is not changed. Given the crazy parts shortages a lot of that is going on right now. I’ve been in the middle of this mess with multiple circuit designs for the equipment the company I work for produces, and no we haven’t changed part numbers etc. as far as the customer knows they are getting the exact same thing.

I have a TH-8600. The radio is built like a tank, but that's about it's only good point. The power output is noticeably below the claimed values for VHF and UHF. The worse part is the receiver. The selectivity sucks. Any moderately strong station, in my case UHF, breaks through on numerous programed memory channels. I had to lock out several FRS/GMRS channels because a UHF fire dispatch transmitter some 15 to 20 miles out would break the squelch during scanning so well I thought it was a local transmitter on the frequency! Unless you're way out in the country side, no high power transmitters around, I would NOT recommend this radio.

They are basically the same radio. One of the interesting thing is while using the engineer/lab version of the software and looking at the radio's info read output I saw it also had two serial numbers. One for NXDN and the other was for P25. Go figure that one out. That sort of goes along with a post, which I can't go back and find, where the claim was made that the radio could be switched between the two modes with a firmware change. It sort of makes sense since the vocoder is done in software running on a separate DSP chip in the radios. The DSP chip does the encoding/decoding and protocol work. Changing the DSP code would be the only thing required so long as the modulator could generate the right RF signal. Bench marking a digital radio is not like doing an analog one. For example with DMR the bandwidth is 12.5KHz. With NXDN the much more narrow bandwidth is 6.25KHz. The narrower bandwidth also rejects more noise compared to the main signal. That can have the effect of improving the signal to noise ratio over lets say DMR. I don't have any proof, since one can't see the source code for the DSP, but some of the filtering is likely done there since it's possible to implement far narrower filters, than what is possible in analog hardware, WITH repeatable characteristics. You can't ISOtee test something like this since you don't have access to the data stream coming out of the digital filter to gauge it's effectiveness. It's all internal to the DSP. I wouldn't be surprised if Motorola wasn't doing something similar too. You can implement DSP algorithms in FPGA hardware instead of a DSP chip. I believe Motorola does use an FPGA in their radios. The manufacture may have skimped a bit on the analog half since the real market for the radio is for digital use. The reason why the analog section is there is an upgrade/migration path for the end user. They don't expect, or hope, the user will use the radio for analog long term. Otherwise why buy one? They have cheaper analog radios. I have some idea what DSP filters can do. I had a project where I downloaded some waveform data from a digital scope into a package called MathCAD. It has some DSP and FFT/IFFT functions in it. I used those to make a filter to get out the high frequency noise due to the switching transients and ringing in the scope data. It was amazing to see just how well that works.

There are some Kenwood radios with built in GPS. https://comms.kenwood.com/common/pdf/download/02_NX-200G&300GBrochure.pdf For the radios that don't they have speaker microphones with the GPS receiver in it which will transmit the location over the radio. https://www.ameradio.com/product/101091/description.html https://www.kenwoodradiodealer.com/product/107/kenwood-gps-speaker-microphone-kenwood-kmc-48gps

It does look like the XPR7550 but it's a P25 digital mode, not the DMR digital mode. What they mean by "affordable" for a P25 radio I don't even want to look. P25 radios are priced stupidly high in general. https://www.motorolasolutions.com/en_us/products/two-way-radios/project-25-radios/portable-radios/apx900.html#tabproductinfo I've purchased a number of my Kenwood NXDN radios with almost the same spec's as the P25 models for a whole lot less money. That's comparing the NX-200/300 to the TK-5220/5320 models. I do have some P25 radios, when I can find one I won't get raped over on price. https://pdfs.kenwoodproducts.com/2/NX-200&300Brochure.pdf https://comms.kenwood.com/common/pdf/download/TK-5220_5320_Specsheet.pdf

22 channels. You can't run simplex on the 8 repeater input channels, they don't count. Unless you ignore the rules.

For mobile radios on the repeater channels ok. With hand held radios using an external antenna. Maybe not.

If you're lucky the signal exhibits a fair about of polarization, vertical or horizontal. If your radio has a signal strength indicator try rotating the radio 90 degrees. Then turn in a circle and see if the noise will null out completely or to a significant degree. Try to get a compass heading. The noise source should be in line with the axis of the antenna. Repeat at several widely space points. Hopefully you can plot the headings on a map and get a general idea where the location of the noise source might be located. If it's coming from a utility pole, wouldn't be surprised, it could be a bad insulator or loose connection. Each utility pole should have a tag on it with a number. You can report that tag number to the local utility and ask them to come out and investigate and repair as necessary.

You sure you're talking to the repeater that you think you're using? Some repeaters have remote receivers and transmitters. There is a "voting" system that will route the strongest signal to the transmitter from the various remote receivers. Also are there any valleys or tunnels around or through the mountain? A valley could be "ducting" the signal around the mountain bouncing the signal off the valley walls. A large tunnel through the mountain could also function as a kind of wave guide at UHF. The later I've heard about where sailors on board large ships had no trouble picking up local FM stations deep inside while docked at a port. The steel passage ways through the ship acted like a huge wave guide at UHF.

There are is the possibility that some people are using Part 90 radios on MURS, legally. My understanding is if the radio was certified before the creation of the MURS service you can use the radio, BUT it has to conform to the power limits, bandwidth and frequencies set forth in Part 95J. I remember a long while back I had inquired about this issue on these forums. https://forums.mygmrs.com/topic/1239-old-part-90-radios-predating-murs-service-legal-use/ I would be interest in seeing any further thoughts on the topic. This likely should be in another thread. On the topic of a road channel for GMRS perhaps the other question should be is GMRS, using UHF band, a good choice or would something like MURS, license free on VHF, work better?

Good luck with that project. I think in another post I had a link for a very excellent antenna modeling software. The guy who wrote it has retired and doesn't want to be bothered with support issues anymore so he just made the software FREE. I have several versions of it and it does a very good job. It does take some expertise and experience to use it but it's a life saver for those that want to do antenna design. Perhaps you could model the yagis you want to build before doing the actual construction. https://www.eznec.com/ One other gain antenna that works well on UHF is a corner reflector. You can get some good gain out of one of these. https://en.wikipedia.org/wiki/Corner_reflector_antenna This is a simulation of one I did at 435 MHZ for Ham radio use. Instead of using wire elements many use a wire screen mesh to do the same thing.

I can't say the lower loss coax will cause that huge of a difference but it does make a difference. I've use some crappy higher loss RG-58 on UHF because it results in a bit lower SWR as measured at the radio's end of the cable when using a antenna a bit out of it's optimal range. The logic for how that happens is some of the power from the radio is lost in the coax as the energy propagates from one end to the other. When the antenna is not perfectly tuned some of that power is reflected back to the radio. Of course some of that reflected power is also lost in the cable. So the power reflected back, and measured at the radio's end, is lower than what you get with a lower loss cable. The calculated SWR would thus be lower. This is true because the miss-tune antenna reflects the same ratio of the forward power back towards the radio in either case. With the high loss cable you simply get less reflected power.

What he built is called a "Wilkinson" power spilter or combiner. Also there is nothing wrong with building one the way he did it either. You can buy professional ones built the same way. https://www.tessco.com/product/380-960-mhz-2-way-splitter-w-n-females-313184 The coax impedance should be 70.7 ohms for the ideal match, not 75 ohms. Using 75 ohm coax the calculated SWR assuming a pure load of 50 ohms is 1.22 : 1 under ideal conditions. Still not bad. Also if you don't use type "N", BNC or SMA true 50 ohms impedance connectors but use SO-239/PL-259 instead which will really mess things up. Also for a true power spilter/combiner you should have a resistor RF load between the two load ports. That's in case one of the loads fails, opens up, the source still sees a good match. This is very often left out of many designs. It still works, just isn't screw up proof. https://en.wikipedia.org/wiki/Wilkinson_power_divider http://www.ittc.ku.edu/~jstiles/723/handouts/Wilkinson Divider Even and Odd Mode Analysis.pdf

It's not so "simple" when people regularly propose to use their favorite channel for the "official" travel channel. It's useless to a new GMRS user who reads in one place that channel xx is the travel channel, then later somebody else says it's channel yy, then even later another claims we should all be using channel zz because it's what some other radio service uses. Just thank GOD we only have 22 channels so the confusion is somewhat limited. Maybe the government can step in and mandate channel usage like Australia has done with their license free UHF CB radio service. They have 80 channels. https://summerstar.com.au/blog/uhf-channels-australia

If you can't afford $70 for a license good for ten years you likely can't afford to buy a radio to use the license either.

Seems like regularly somebody wants to advocate for their favorite channel to use as a travel channel. Just program all 22 in, scan them all and be done with it. Then it won't matter.

And the best part they manufacture themselves, no chip shortages or high gas prices to worry about. The waste products are naturally recyclable. When the bombs fly and the big EMP event they will still keep working too.

I'm running Firefox on Linux, OpenSuse, and when I click on the link it asks if I want to use Libreoffice to open the file. I have that package installed so it works for me.

Yup. All valid points. The old stuff gets used because it was cheap, like saved from the e-waste guys for free, and recycled. Hams are cheap. I guess that's why many own a Baofeng too. Oh well.

Depending on the vintage of the equipment yes it may have to be hacked. Some of the older Part 90 stuff has to be "re-crystaled" and re-tuned to work outside of the original specifications. Yeah there is some REALLY OLD Part 90 junk out there that should be in a land fill being used on the Ham bands. There are all sorts of things that can go wrong, a few you might not have considered. One nasty type is caused by mixing in the output stage of a transmitter caused by signals getting in through the antenna port. The transmitter looks great on the bench with a spectrum analyzer and dummy load until it's installed on site in close proximity to other high power transmitters then the problems crop up. https://www.softwright.com/faq/support/intermod_finding_solving.html I in noway inferred the Black SUV will be rolling out. My comment is simply Ham built systems have a bad reputation with some people, justified or not. Some site owners will not allow Ham equipment just so as not to piss off their paying customers. Hams are basically cheap and look for no rent locations. Some even get free electricity and network access. A buddy at my Thursday night coffee group has one at a local school. He's not paying a cent for his UHF repeater with free power, including backup and Internet access. So, if a site owner can use the objection from his paying customers over a Ham system, who are likely paying basically nothing, and sell the space to somebody else for good money that's all the motivation they might need to reject the Ham equipment. Is that fair? But that's business.

I've heard stories where Hams can't get their equipment colocated with commercial equipment on building roof tops and towers because the commercial guys don't want to waste their time trying to trouble shoot issues with their equipment caused by poorly maintained or modified Part 90 stuff to get it on the Ham bands. They have a business to run and people pay good money for the service(s) they provide.