Lscott

While that is true one thing you can do with DMR, and not with NXDN, is setup a SRF, Single Frequency Repeater, that doesn’t require an expensive set of tuned cavity filters. Several DMR radios have the functionality already builtin. This is due to DMR being TDMA verses NXDN’s FDMA mode.

Based on the good comments on the forum I ordered one myself from Bluemax49er for a Kenwood NX-820GH mobile radio I was given. I might have found one cheaper but I feel confident this will work without issues. Too many super cheap Chinese cables using the counterfeit Prolific chip that don't work out there.

If in fact the noise is coming from the car stereo it's likely radiating from the wires between the speaker output and the speakers. Many new car stereos use Class D power amplifiers. To make it simple its a switching type circuit operating at high frequency, HUGE noise generators if not filtered. If the filtering is insufficient on the amp's output you can try putting your clamp on ferrites on the speaker wires right at the point where they exit the amplifier. You might even have to shield those wires and ground the shield right at the stereo. https://www.analogictips.com/class-d-amplifiers-for-high-efficiency-switched-mode-sound/ The communications between the head unit and the main body is also likely using a fast serial communication protocol. One common protocol used extensively in automotive settings is the CAN bus. Those signals may also be a source of noise radiation and might need those clamp on ferrites too. https://en.wikipedia.org/wiki/CAN_bus

Great! Let us know how it goes when you get all the bits put together and the radio programmed. The narrow bandwidth and low power FRS channels are 8 to 14 at 0.5 watts. Channels 1 to 7 are 5 watts max and wideband, while the repeater main channels 15 to 22 are wideband and 50 watts max. I just added another Kenwood TK-3170 and my first TK-3180 to my HT “collection”. I spend to much time on eBay and can’t pass up a good deal. 8-/ The programming software for the TK-3180 complained about several features that may not work right because the firmware was too old. After contacting Kenwood support they were nice enough to supply me with the most recent version. Didn’t even fuss about it. I might have to buy yet again another different programming cable myself. I have a buddy who got his hands on a used Kenwood NX-820HG-K2 and mic from his work place they were going to dump. He has no interest in digital radios, it also does analog, so he said I could have it if I wanted. Now I need the cable. It’s not part 95 certified however. https://comms.kenwood.com/common/pdf/download/10_NX-720HG&820HGBrochure.pdf

The FCC certification grant is located here for the TK-880. https://apps.fcc.gov/oetcf/eas/reports/Eas731GrantForm.cfm?mode=COPY&RequestTimeout=500&application_id=9wLBCa2uBguLpUibGdVsCA%3D%3D&fcc_id=ALH24593210

If you're looking for the TK-880H brochure with the basic radio spec's look here. https://www.ameradio.com/doc/Kenwood_TK-780%28H%29.pdf

Many business use FRS radios that now share the same exact frequencies for simplex as GMRS. It’s legal for them to use FRS for business purposes. What you are most likely hearing are FRS radios.

Yup, the same attitude that permeated CB back in the 70's. FCC required a license but most users said screw it, or if they had one didn't ID as required. After a huge increase in the number of CB radio users the FCC gave up enforcing the license use and ID requirements, then changed the rules to make the illegal behavior legal. That way they washed their hands of having to deal with it. Hopefully GMRS doesn't follow the same path.

Some virus software will falsely flag perfectly OK files as infected. I had Norton AV years ago kept deleting the main EXE file for a $4500 microcontroller development environment I tried installing several times that I needed to use at work. I finally had to but the name of the file in an exclusion list to keep Norton from screwing with it. Very aggravating.

Looks like you need to trim your antenna. The question is it too long or too short. If the antenna provides a means to adjust the length a bit try that first. As far as the SWR going up after cutting the coax length down a bit isn't surprising. The SWR depends on how much power is output by the transmitter and what fraction of that at the end of the coax is reflected back by the antenna. A longer length of coax results in less power reaching the antenna and the reflected power, as a fixed function of the antenna match itself, is further attenuated by the extra coax length. The end result is a lower SWR as seen at the transmitter end.

All valid good points. When I was running around the country doing service for a few years I also took my FT-817 with me. Tried to get hotel rooms up on the top floor where possible. Used a small camera tripod to support some VHF and UHF antennas. Made a few surprising contacts on 2M SSB that way.

I was just thinking based on your story about getting out of the path of a hurricane and keeping track of everyone perhaps APRS would be the ticket. You can find info on it here. Basically APRS uses a GPS receiver connected to a radio which will periodically, and automatically, transmit you current GPS position to any compatible radio in the area. This data can also be displayed on a map accessible on the internet so anybody can see your location if one or more of the RX'ing radios has an internet connection. Even if there is no internet access close by APRS can use special APRS digital repeaters to propagate the APRS packets over a very large area. http://www.aprs.org/ Mapping. https://aprs.fi/#!lat=42.6206&lng=-82.9608

If the FT-818 has about the same output filter as the FT-817, I own the original version with the MARS/CAP mod, the power drops fast above the upper limit of the Ham 70cm band. Around 462 MHz it does about half power max, and at 467 MHz lucky to get 1 to 2 watts out of it at best if you are thinking about GMRS access for emergency comm's. Also the radio won't tune above 154 MHz on VHF so even on RX you can't get any of the NOAA weather stations. The later seems to be a big complaint with even the unmodified radios since the market for is is QRP operation while camping, hiking etc.

This is the mod to open up the RX and TX on the above radio. https://radioaficion.com/cms/th-d74-modification-of-the-us-version/

Try looking at the Kenwood TH-D74A if price is not a problem. I have one with the mods to open up the TX and RX ranges, https://www.kenwood.com/usa/com/support/pdf/TH-D74A.pdf I ordered mine from here and they will also do the MARS/CAP mod for you as an extra cost option. https://www.hamradio.com/detail.cfm?pid=H0-015269 You might want to look around a bit for a better price. I paid $550 with no mods when I got it a while back.

If you don't have a good ground plane for the 5/8 wave then the only alternative is using a 1/2 wave antenna, they don't require any kind of a ground plane. You need a really good ground plane for any 5/8 wave antenna to get a good match and realize the slight gain you get from using one.

Oops. The one link is for the repeater. Editing and copy paste isn’t the best on a smart phone when you’re tired. But you get the idea.

One of the first things I do when interested in a model of radio I’m not familiar with is look for any manufacturers brochures. That gives a quick run down on the features. If no luck then look for the user manual, service manuals etc. https://www.ameradio.com/doc/Kenwood_TK-7180_TK-8180.pdf http://www.repeater-builder.com/kenwood/pdfs/tkr-740-840-brochure.pdf

A bigger handheld isn’t necessarily a bad thing. If you use your handheld radio with a moderate to high duty cycle it’s going to get real hot! Some time back a Ham wrote, on another forum, he failed the output stage on his TWICE from over heating due to a high duty cycle. A larger radio has a larger metal sub-chassis, thus more thermal mass and more area to radiate heat. If you look at the typical specifications it shows 5-5-90. That’s 5 percent TX, 5 percent RX and 90 percent standby with no audio for battery life but it can also be applied roughly for thermal consideration.

I don't have any experience with the Kenwood mobile radios so I can't address that question. The Kenwood TK-3170 is a good radio. You should also consider the TK-370G-1, TK-3140-K (Type 1) and the TK-3173-K (Type 1). I have all these models and they work fine on GMRS, repeaters, simplex, split tones (analog and digital) and will program down in to the upper part of the Ham 70cm band. I have a TK-3180 that should be showing up in the next few days from an eBay purchase so I'll see how that works out. The TK-3173 is a TK-3170 but has built in trunking functions, which you don't care about for GMRS, but otherwise they are almost the exact same radio and use the same software. When you buy a used radio try to find out if it's password locked. One of my TK-3170's showed up with a data read and a data write password. That prevented me from reading or writing anything to the radio. It took a while to track down a real "engineer's" version of the software which allows you to blow by any passwords in the radio to read it and then write your own code plug to it. The software also seems to have provisions for "hex editing" the radio's memory and a few other things the normal dealer or end user software won't allow. I also have the "engineer's" version of the software for the TK-3180 just in case there are some "surprises" when I try to program it when it arrives.

If you go that route, two radios, the separate 2m and combo Ham 70cm with GMRS is a recommendation. All of the Kenwood commercial HT’s radios I have all will program down into the repeater section of the Ham 70cm band and most of the simplex section. So I can use just one radio for both services so long as it’s on UHF. When I’m not going to the gym I go for long walks so having just one radio is a big convenience for access to both services.

If the radio supports a STUN function but the user doesn’t have a code entered that won’t work. Of course you would have to know what that code was before hand, which if it’s an unknown user you won’t have it. Changing input PL codes works for a very short time with a determined jammer. It only takes a few minutes curchunking the repeater using different analog PL tones until they hear the squelch tail. There are only around 38 to 40 of them. As far as using an output tone that isn’t that effective either. All my radios, CCR’s - Ham - commercial, there is a provision for entering a RX tone, which I never use. In that case I don’t even care if there is a tone on a repeater output, I’ll hear anything that’s there. The purpose of STUN codes is to disable a lost or stolen radio that you own and programmed. On all of my radios I get used that’s one of the first things I make sure is cleared out. I would suggest using a digital tone, there are more of them. Also using an uncommon repeater access method, like MDC1200, might work out better. The later isn’t that common outside of Motorola radios. Only a few of my commercial Kenwood radios have it for example. One other idea is to also use a non standard repeater split. There is nothing in the FCC rules that requires the repeater split to be exactly 5MHz. The requirements are one frequency from the 467.xxx input group be used and one from the repeater output group, 462.xxx, be used. Any radio that has preprogrammed repeater channel frequencies won’t be able to use the system setup using an odd spilt. In the Ham world I’ve run across a few odd repeater spilts so it’s been done there.

Yup, I have my TK-3170's and TK-3173's programmed up with Ham simplex and repeater frequencies along with the GMRS stuff.

These seem to be rather rare to find, at least for the times I've looked. There was one on eBay a while back but I didn't want to pay the asking price. The TK-3180 with the 450 to 520 split I'm getting looks in very good condition and the seller wanted $55 which includes shipping, battery pack and a somewhat broken antenna, which I have aftermarket replacements. By the way there are a couple more he's selling listed. I have the software installed with the "engineer's key" so I can bypass any passwords that might be on the radio.

I'm thinking about getting a used Kenwood TK-3180-K (450-520) radio to experiment with. How much luck has anybody had getting the radio to work down into the Ham 70cm band? If so how far and any issues with power or sensitivity? The KPG-89D software will allow the out of band entry after clicking the button in the popup warning window.