Lscott

Great. The service manual came in handy for me. I got two identical dead hand held radios off eBay. Swapped parts around and got one functional. Used the service manual with the diagrams to identify the failed parts and their Kenwood part numbers. Now I can order them and get the second radio fixed. You never know what you may need the documentation for at some point. One other thing I do myself is look for the radio programming software. If I can't get it then the radio would be nothing more than a paper weight and not buy it. I wouldn't send it to a shop to have it programmed. I end up modifying the code plugs from time to time and have different ones depending on what I plan to do with the radio at the moment. I hear too much about Motorola radios and how they handle the programming from a friend who is a radio tech for a local city transportation department. Then the licensing costs for the radio programming software from another friend and his Mototurbo digital radio. I have another friend looking at some used Motorola P25 radios on eBay to use simply as a scanner for public safety monitoring. He says its cheaper than some scanners he looked at. I at least have had good luck getting the Kenwood stuff. Wish you luck and hope the project works out well. On occasions I've felt a radio would work better if it bounced off the wall a few times. 8-\

Everybody has their favorite digital mode. There are enough of them, D-Start, DMR, P25, NXDN and Yeasu's System Fusion to name a few. The fly in the ointment is which "standard" will be the majority of people end up using? Bet wrong and you end up with a radio with dwindling support. So far I haven't seen, or know about, a small hand held radio that offers more that one digital mode. Thus if you use more that one mode you end up with a separate radio just for it. The next issue depends on the digital mode. While radio to radio contacts are basically straight forward going through a repeater is not. The problem is some digital modes may not be compatible with old analog repeaters. The old analog repeater has to be replace at the owners expense with digital compatible equipment. One of the attractions of digital modes is the ability to link repeaters together over the Internet using various VOIP protocols. That requires access to a high speed Internet connection and a sizable infrastructure to handle the VOIP packet routing etc. like routers and gateways, Then there is the need to register to get you own unique ID so your radio can be identified within the digital network and the VOIP traffic routed to it. Digital modes are a lot of fun and have their advantages. One just has to understand what maybe involved and plan accordingly. 8-))

Many USB to serial cables use a chip manufactured by a company called "Prolific" inside. The chip is a popular one so it didn't take long for it to get cloned. The cloned chips were cheaper than the official one. To combat the spread of the cloned chips the company wrote code into their driver to detect the clones and refuse to work with them. The fix to get cables using the cloned chips to work required finding an older version of the driver before the detection code was added. Your other choice is to get a cable using a real Prolific USB to serial chip or the other type using a FTDI type chip in it. https://www.ftdichip.com/USB.html Trying to use a cable with the cloned chip the driver appears to install OK but you get error messages when you use it with the newer drivers. Note that some Chinese radios use the USB to Baofeng type plug, but it's a pass through cable only. The USB to serial chip is built into the radio. My D878UV is like this. Using the Baofeng type USB to serial cable results in connection fail and other error messages. I have to use the specific cable the radio shipped with so its packed away and labeled for use with that radio only. You can buy the USB to serial cables online. The one I have was sold by R and L Electronics in Ohio. I've used it several times to test a code plug for for my TK-2170, the VHF version of your UHF TK-3170 radio. It works fine on that radio and some other ones I have. Used it on both Windows 7 and Windows 10. I didn't do anything special, just plugged it in and let Windows install the driver. http://www.randl.com/shop/catalog/product_info.php?products_id=71426&osCsid=h5bd4ajsq8bnulahcnmjsa27i6 As long as its the same manufacture as the one I got, didn't switch suppliers, it should work. Mine has "Baofeng" on the fat end that plugs into the computer's USB port. If you look around on the Internet you can find PDF copies of the radio user guide and service manuals. Useful to have. Also if you get the FCC ID off the back of the radio you can search the FCC database where you will find the test reports and the FCC grant, Part 90, 95 etc. for example, the radio is certified. https://fccid.io/

You can down load the Kenwood programming software for your radio from the location below: http://www.radioscanner.ru/files/kenwood/file8416/ The download link is near the top of the page. The file you want is "kpg101d.zip" The zip file should also have the license key you need to enable the software install. I have it running on Win 10 Home. I used this software to load a test code plug in to a used TK-2170 I picked up. The radio uses the Baofeng type programming cables. If you buy one make sure it doesn't have a fake "Prolific" serial to USB chip in it. This site has the info about the cables: http://www.miklor.com/COM/UV_GettingStarted.php Sooner or later you are going to want to make changes or load the code plug up into another TK-3170. No point in paying somebody when you can do it yourself.

I wouldn't recommend doing this. The signals on the ribbon cable are very likely logic signals, some anyway, that have sharp rise and fall times thus a high frequency content. Extending the ribbon cable would be the equivalent of a transmission line. If the line was not terminated in the proper impedance at each end then you get reflections. Those appear as high frequency ringing on the logic level transition edges. The voltages can ring above the supply and below ground which can result in damage to the chips on the boards if they exceed the max spec values. Additionally the ringing will look like extra logic transitions further confusing the logic on the boards. Once in my younger days I tried to use the expansion slot on the back of my then new TRS-80, it ran between 2 to 3 MHz, using a 2 to 3 foot long un-terminated ribbon cable to the solder less breadboard. I wanted to try experimenting with some computer controlled hardware. The computer wouldn't even boot to the built-in BASIC interpreter until I removed the cable. Lucky nothing was damaged. Lesson learned.

Yeah, I know about the software bugs with the D878UV. Hardware wise it's a nice radio. At least the front end seems better at rejecting out of band or off frequency signals compared to the other cheap Chinese radios I have. The downfall is the firmware and the customer programming software. If you look about every 1 to 3 months they come out with a new version of both ever since the radio was first released. They fix something in one version, then it's broken in the next. I don't understand why when they fix a bug it doesn't stay fixed in later releases. The last one, V1.17, that just came out a few weeks ago I just sent off another bug report about a couple of things that don't work I stumbled a cross or just plain annoying until they get fixed. Now by contrast my TH-D74A has only a few updates and when the bugs get fixed they stay that way. Yes its an expensive radio but you get what you pay for too.

The site below has some good info on the Anytone, Alinco and Btech DMR radios. http://members.optuszoo.com.au/jason.reilly1/868mods.htm Oh, mode 00014, the password is "878#" typed in without the quote marks.

Actually going to a lower loss line could make the SWR worse as seen from the radio end. The reason why is the energy reflected from the antenna back to the radio is attenuated less, more reflected power, that would otherwise be adsorbed by the feed line. The SWR can be calculated using forward and reflected power using the formula below: SWR = (1+sqr(Pref/Pfwd))/(1-sqr(Pref/Pfwd)) Where "sqr()" is the square root of the value inside of the "()". And "Pfwd" is the measured forward power going to the antenna while "Pref" is the power being reflected by the antenna miss-match back to the radio.

I would NOT recommend using PL-259 and SO-239 connectors at UHF. They are not "constant" 50 ohm impedance. Depending on how many you have and where in the system they do tend to degrade the SWR. Good connectors to use at UHF are "N" type, BNC, mini RG8, SMA are the more common ones. Many mobile and base radios use an SO-239 on the back so you can't do much about it. The better ones use the "N" type. Where you see SO-239's used look at the inside of the connector. If you see what looks like thin a web between the outside of the center pin and the inside of the outer shell, like the spokes on a wheel, cause less of a problem compared to the solid filled ones. This is done to improve the impedance of the connector to bring it closer to the desired 50 ohms. The antenna ground radials, if required, should be around 1/4 wave length long, approximately 6 inches long, and could be bent downward at a 45 degree angle from the horizontal. Some of the antennas that claim not to require a ground plain are a "J-Pole" internally. These antennas should have several turns of the coax located right at the base to decouple it from the outside of the coax shield. If this isn't done then RF current flows on the outside screwing up the antenna TX and RX pattern, RF getting into the radio resulting in TX audio distortion and in addition to causing weird SWR problems. If your SWR is 1.3 to 1.5 there may not be much to gain by improving it to the ideal 1 other than to make one feel better. Most radios are designed to tolerate SWR's up to 2 at full power anyway.

Maybe I should take another look at the 629's.

I was looking at the 628’s, not the 629’s, originally. Now I’m not sure. I just purchased a Kenwood TK-2000 package with programming cable and software new on eBay for $50. I was going to experiment using that radio and a Baofeng BF-888 with an MFJ-916 duplexer to make a simple low power VHF/UHF cross band repeater.

Which ones have you used? I've been looking at reviews on these on and off for a while and I'm not likening the comments I've read, to many negative ones. Yes I've seen the comments about the first half second being cut off. That's happen to me with radios with VOX operation or a VOX headset so seeing it mentioned with the controller isn't a concern. All it means is the electronics needs enough audio signal level to detect long enough to ensure somebody is really talking so the radio TX isn't tripped randomly. What gets me are reports about out and out failures or the audio is fine for a while then for no reason is distorted. Some reports the controller will no longer switch the TX radio on etc. One guy said power cycling his would fix the audio distortion problem on his for a short while then mess up again. Then there are people like you who say they have no issues. From those that don't report issues to the frequent ones who do I begin to question the manufactures quality control.

If you want to do an "in-band" repeater you will need two radios, a duplexer and a controller as the main components. You can buy a cheap UHF duplexer at this site. If you supply the two frequencies they will tune the filter at no extra cost. Also don't forget to get any N to whatever RF adapter you will need to connect to the radios and the antenna. www.409shop.com/409shop_shopcat.php?&usercat=4942 If you want to know how well these cheap Chinese duplexers work a guy did some testing on one here. http://www.repeater-builder.com/antenna/pdf/chinese-mobile-duplexer-measurements.pdf Then use a simple repeater controller like this one. https://radio-tone.com/product/rt-crc1-repater-controller-full-duplex/ I see ad's for the "Surecom" controllers but have read a lot of bad or poor reviews. The one above seems to be OK. Also don't forget to get the right radio interface cables with it.

Or do a "parrot" repeater. This is where you TX and the controller will record the message. When you're done it then re-transmits the message. This of course slows down the communication, and some find them annoying to use, but are simple to setup using one radio and fairly cheap. There are several YouTube videos where a guy did this putting the guts in an ammo can with a battery and charge controller connected to a used solar panel. He used the metal ammo can for the ground plane required by the antenna. Stuck it on a mountain top in a very remote area. Had it there for about a year or so running before having to service it. The repeater controller he used should be like this one. https://www.argentdata.com/catalog/product_info.php?products_id=98

Also you can't crossband between the Amateur Radio service to GMRS or MURS either.

What does the local terrain look like around the site? Another point to consider is very high gain vertical antennas have a narrow radiation pattern perpendicular to the antenna. General reciprocity antenna theory says the RX and TX patterns should be similar. Anyone close in will have a hard time getting into a repeater like this since the antenna is deaf if you're not in the RX pattern. Commercial broadcasters and some repeater installations use antennas designed so that the narrow radiation pattern is not perpendicular to the antenna but has a small "down tilt" angle of several degrees to compensate some what for this condition. A lower gain antenna has a wider RX and TX pattern perpendicular to the antenna. The gain fall off is less severe. That's why you read about people claiming that a simple 1/4 wave on UHF gave them better results in hilly terrain verses using a high gain antenna where other stations are at different elevations relative to each other.

Oh, one more point. Be careful what version of a radio model you buy used! For example the Kenwood TK-370's and TK-370G's come in several variations that cover different ranges in the UHF band. You want to pick one that covers 462 MHz to 467 MHz. There are 4 versions of the 370's and 370G's. 450 to 470 470 to 490 490 to 512 403 to 430 If you get a 370 you want the "type 1". The ID tag, on the back of the radio on the aluminum chassis under the battery, should show "TK-370-1" or "TK-370G-1" on it. The type 1 is the 450 to 470 range. The radio will also program down in to the Ham 70 cm band to around 440 MHz. The Kenwood software will complain its out of range but will let you do it anyway. The radio will work there which is convenient for those dual licensed for Ham and GMRS. 8-)

I agree. I've picked up several Kenwood TK-370's (wide band 32 channel, repeater operation, 4 watts), also have several TK-370G's (wide/narrow band 128 channel, repeater operation, 4 watts). Both have part 90 and 95 certification. If you search and wait you can get one at a fair price on eBay. The programming software is easy to find on-line. These radios use the same exact cheap "Baofeng" programming cables. Just make sure the one you get doesn't have the cloned USB to serial chip in it, the newer windows drivers don't work with them. Parts for these radios are easy to find. You can get the drop-in battery chargers, battery packs, antennas etc. The TK-370G uses the reverse SMA antennas. The TK-370 however uses a Motorola MX type but you can get a MX to BNC adapter to use an external antenna. If you buy a used radio be sure you can get the programming software and cable for it! Just about every business band radio has to be setup using the software because there is no "front panel programming" typically, at least on the hand held radios.

What is the source you got the graphs from and how were the tests done?

Military man pack radios I haven't used and don't really know much about them. I would suggest you search around the Internet for a group(s) that specialize in that kind of equipment for info.

Going for your Amateur Radio license, great! About commercial radios for GMRS use. Look carefully at the FCC certification. If you can find the FCC ID you can look up the different FCC parts the radio is certified for operation. Some have Part 95 which means they are legal to use. There are various opinions about if Part 90 radios can be legally used. That's covered elsewhere. For example I have a couple of Kenwood TK-370G-1 radios with an FCC ID of ALH29473110. I also use a Kenwood TK-370-1 with an FCC ID of ALHTK-370-1. You can look up the FCC ID's at: https://fccid.io/ The next issue with commercial radios is there could be several sub models that cover different frequency ranges. Be sure the one you are looking at will work over the 462 to 467 MHz range. The final big issue is the programming software, AND the cable. For many radios they are NOT front panel programmable. Thus the only way to set them up is with the manufacture's software. If you're really lucky the open source software "CHIRP" may work. In my experience it works great for some radios and others it's very buggy.

Yes some people do get it confused. What I'm looking for is the equivalent of a 1/2 wave antenna, thus no ground plane is normally required. The Comet CA-2x4SR does require a ground plane as I suspected from my testing. I confirmed this the other day by contacting Comet tech support. The reply I got is quoted below. "The CA-2x4SR is a 5/8 wave, so yes it must have a ground plane underneath the antenna in order to work properly. It was designed to be installed on sheet metal, like a vehicle trunk deck, hood, or even hatch back door. You need about 20” radius of metal under the antenna, but rarely is it possible to create a ground plane that provides the impedance needed at the antenna feed point. If you can use one of our lip mounts attached to the door edge, or hood edge to provide the ground plane." From my SWR scans you do need a really good ground plane. A magnet mount sort of works but a good direct electrical connection to a ground plane, or set of correctly cut to length radials, works even better from what I see.

Just and update I got an email from Diamond Antenna this afternoon. They have a new product in the works. This was the info I was sent below in quotes. "We will have the NR240A in a couple of months. This antenna, when on a mag mount is 140MHz-170MHz and 430MHz-470MHz. When it is grounded on a hatch/lip mount it is 140MHz-165MHz and 440MHz-465MHz. " Looks close to the spec's for the Comet wide band antenna. If the above is correct it seems the antenna is optimized for a wider bandwidth using a magnet mount? That is unless they got the magnet mount verses the hatch/lip mount bit swapped. Either way it looks like there will be an alternative antenna. I just wish it didn't require grounding. More new vehicles have plastic body panels so grounding gets harder to do.

I'm sure you're right. This was the point of asking. I did send an email off to Diamond Antenna a few days ago asking if they even offer anything like the comet CA-2x4SR. Never got a reply to date. I wish Comet still made the CA-2x4MB. The only failing was the spring for the fold over feature lost tension so the antenna would lift out of the socket then flip over at highway speeds. I had to wrap several layers of tape around that area to stop it. Other than that it's worked fine for years. I haven't had any issues with loose hardware, screws, or rust. If anybody has any interest I have the AA-1000 SWR scans of the CA-2x4SR on the roof of my Jeep using a 5 inch magnet mount and inside the house using a home brewed mount with 4 drooping radial elements, which gave the lowest SWR scan curves, much better that the specs in the Comet datasheet. I was rather pleased to see that. For the moment I can't seem to attach any files to upload. The message says I only have 666 bytes left. Not sure why it's still limiting me or is there a time limit that has to expire first before the upload limit is reset.

I can't seem to add any more files at the moment showing the scans for the Ham 2M and 70cm bands, which look just as good. The stated antenna gain is 4.5dbi from 145-148 and 7.7dbi from 440-450 with an SWR of less than 1.5, the graphs in the datasheet show over the above range a max SWR of 1.2. The antenna is about 59 inches in length, a big one.