Lscott

If you mean by "bubble pack radio" the ones you see at the department store I would say no. The FCC changed the rules back a few years so combo GMRS and FRS radios are no longer legally sold, and a few I think did include repeater access. What you will find are likely FRS only radios which by law can't have repeater functions. I think your best bet is researching online specifically for GMRS radios, then look carefully at the spec's or get a copy of the operator's manual. Check to see if repeater setup or functionality is specifically mentioned and how it works. As you discovered some don't. One more thing if you want repeater access have you checked to see if there are any repeaters, and are operational, within a few miles of where you plan to operate? If not then repeater functions on the radio won't help you much. Any handheld radio you do get I would recommend it should have a removable antenna. This way you can use it while mobile with a simple 1/4 wave magnet mount on the roof, or switch to a better on-radio antenna. The range is severely reduced using the on-radio antenna while inside of a vehicle. Some people use a magnet mount on a cookie sheet for a ground plane to use inside the house for limited range, usually better than the on-radio antenna.

I just tried all three links just now and they all work. Perhaps you need to try again or another browser.

This is a link for a commercial RF sampler, "ISO-Tee", connector. https://www.rfparts.com/rfa4059a.html

Just for my info can you provide some details on how you performed the tests? For a home made iso-tee connector they have to be calibrated, from some sources I've read, before each use. I found a nice write up on how one guy did his testing along with photos for those who might like to know how its done. Also how somebody made their own iso-tee connector. I'll admit it's done with a crappy "UHF" type connector but it's just the general idea. http://www.repeater-builder.com/antenna/desense-testing/desense-testing.html https://urgentcomm.com/2007/09/01/every-toolbox-needs-one-of-these/

The point about over paying for commercial quality Part 90/95 radios, yes some do in fact have both FCC certifications, should not be poo-pooed, especially on places like eBay. Personally I've purchased somewhere around a dozen such radios, hand held models - all Kenwood, to add to my collection. I've seen the exact same models selling for a good price to nearly 4 times more in the same condition. Some are listed as non functional or damaged but the seller still wants way more that other sellers that will guarantee their radio will work or you can send it back for a refund. Go figure. I see overpriced radios, functional or not, being relisted on eBay over and over again. Just for fun I keep them on my watch list to see how long they last before the seller gives up or gets reasonable with the price. Some of them have been relisting for almost a year at the same over priced point! A few times I've sent the seller a private message through eBay offering what I think is a good price. I've gotten some very good deals this way. I try this even if the seller doesn't have the radio listed for bids or best offers, just a fixed price. A few took my offer since they just wanted to get rid of the radio and not looking to make huge profits off the sale. Most just say no or ignore you. Then you wait to see how long it takes for reality to set in and they drop the price on their own. 8-)

I couldn’t agree more.

If you don't have (1) the right equipment and test jigs to make accurate measurements and (2) the experience/expertise to do this then I recommend you don't try it. Your typical HT antenna is a 1/4 wave long without internal loading coils. For GMRS frequencies the antenna should be somewhere around 6 inches long without any loading coils. So if somebody cut one down to 1 or 2 inches they very likely screwed up the measurement and or the test jig was very seriously miss designed. I have seen "special" 1 or 2 inch long UHF antennas. They have a construction where they have a build in loading coil to provide the inductance lost due to the antenna being shorten. These antennas are VERY lossy and are likely not much better than a dummy load screwed on to the radio.

I looked at a photo of the antenna base. Given it's a gain antenna I'll guess the first section is maybe a 5/8 wave. A 5/8 wave antenna needs a very good ground plane right at the base of the antenna. Using the mount you have, while it is "electrically" grounded through the set screws may not be sufficiently close to the antenna base, where the matching section is located, to function as a good ground plane. You can check that by using an NMO magnet mount type base located in the same position where the current one is located.

I went and downloaded the brochure for the EVX-531. It looks like a dead ringer for the Kenwood I have coming, about the same feature set but with a bit more output power, 5 watts verses 4 watts, which likely isn't that noticeable in real use. For anybody that is interested the brochures are located here. Both seem like nice radios. EVX-531: https://www.buytwowayradios.com/downloads/dl/file/id/747/product/3688/vertex_evx_530_series_product_sheet.pdf TK-D340U: http://comms.kenwood.com/common/pdf/download/DMR_TK-D240V_D340U_K_letter_1124.pdf

The Kenwood is only costing me $46 including shipping. I located the programing software on line as a free download with the SN required for installation. I’m not against Motorola gear, but I have a collection of Kenwood accessories that works with all the various models, except for the TK-2140/3140’s that need the “Motorola” multi spring pin type connection. The same accessories, including the programming cable, also work for the few CCR’s in the collection. Having to deal with 5 to 6 or more battery pack types and charges the various radios use is a pain already. I have a pile of used battery packs that I don’t have a good measurement of the remaking usable capacity. I’m looking at buying a good new programmable electronic load with a battery capacity test mode. Also can use it for running tests on solar panels. The typical end of life, EOF, for a battery is when the pack reaches 80 percent of the as new rated capacity under standard discharge conditions for the battery chemistry. Any at the point or less I’ll have to decide if it’s worth keeping for short term operation and testing or goes in the trash bin.

I'm picking up a used Kenwood TK-D340U Type-1 analog/DMR radio on ebay for a good price and I'm looking for a PDF of a good programming guide specifically for this radio. I have plenty of general DMR guides already. I also have the software too, but could use a more detailed guide on the feature set this radio has. The included help file is very brief and light on details. I have programmed a D878UV so a number of the DMR features I do have an idea what they are but Kenwood likes to relabel them using different terminology it seems. I want to make sure I know what the settings do before trying to put the radio on the air using a "from scratch built" code plug. The radio is interesting since it does both analog and DMR, 32 channels total in two zones of 16 each, and wide or narrow band analog. Each memory can can be programmed as a mix mode, DMR in and analog out, analog in and DMR out, or strictly analog or DMR. It also supports the Dual Slot Direct Mode as well. Another point of interest. I can enter out of band frequencies, with a warning popup window, but seems to take the entry. I'll have to wait and see how far I can push the out of band operation limits. I have read with many Kenwood radios it's around 5 percent so that would cover the upper end of the Ham 70cm band, which is all I'm interested in. https://comms.kenwood.com/common/pdf/download/DMR_TK-D240V_D340U_K_letter_1124.pdf

Yup you would doing well to wait awhile for two reasons. You don't want to be "Beta Testing" a version 1.0 radio. Let somebody else spend their money and deal with the problems. While that is going on just occasionally do a search for reviews and see how people are liking, or not, the radio before you spend your money. The second is new radio designs typically sell at the top end of the range the model is targeted for. After 6 months to a year once the novelty wears off, competitors come out with similar models, the price will slowly drop. After some time the manufacture may try to drive sales by offing "manufacturer's discounts" on many of the more well know radio equipment vendor sites. Keep checking to see who is offering the best deal, no sale tax and maybe free shipping. With the holiday season arrival you may find those vendors offering holiday specials. Pays to keep looking around. I was given a free Wouxon KG-UVD1P at a local Ham radio swap. It looked new in the box but no charger. Cost me $17 to get one off of eBay. One of the things I do is look for PDF versions of the manuals, FCC grants and a service manual. Turns out this radio really had a service manual complete with a schematic. That proved interesting. If you are familiar with electronics the schematic can tell you a few things the radio spec's likely won't. In this case the radio was in fact a dual superheterodyne design. First IF was at 29.250MHz using 2 cascaded resonators and the second IF was the usual 455KHz. However the bandwidth on the filters is not delectable so it will be fine on wide-band FM but too wide on narrow band, at least from the stand point of using closer spaced channels. Manufactures do this to save cost. To get narrow band operation the frequency deviation is reduced from 5KHz to 2.5KHz and the audio gain is doubled on receive. https://en.wikipedia.org/wiki/Superheterodyne_receiver By contrast the commercial radios I have use two sets of filters, one wide band and the other narrow band. One even has a "tracking filter" on the input to pre-filter out any potential interfering signals before they get to the IF stages. These radios are designed to work in a very severe and crowded RF environment. You likely won't find this in consumer grade or even Ham Radio grade radios.

You’re right about testing HT antennas. It’s very difficult to get an accurate measurement for the SWR. I know because I tested a bunch I have in my collection. The only thing that seemed fairly consistent were the UHF antennas. At 450 to 470 MHz they only need to be about 6 inches long for a full 1/4 wave, thus you don’t have a real lossy helical wound coil found in the typically stubby VHF designs. Further on a decent sized radio the internal metal chassis provide a fairly good ground plane. When you look at the really tiny shirt pocket radios that isn’t so true. One other reason to stay away from the tiny radios had to do with the heat sinking of the final power amplifier stage. Using them for more that a few percent duty cycle the make wonderful hand warmers. One Ham wrote about destroying his output power stage more than once when running full power at more that the manufactures recommended duty cycle on transmit. On H PO T antennas testing one guy made an attempt to replicate the conditions the antenna sees when on a radio. There were some problems with his test jig that are pointed out in the comments. https://reflector.sota.org.uk/t/antenna-testing-jig-swr/14791

What is the capacity of the battery bank you have? I have a collection of LiFePO4 battery packs, 3AH to 40AH. Also I have several solar panels, none are permanently mounted outside, just deployed when needed. They range in size from 50 watts down to one at 5 watts. I use MPPT's specifically designed for the battery chemistry, most are for LiFePO4 and one is for Lead Acid. I would recommend that anybody looking for a battery type for portable or emergencies not to use Lead Acid types unless cost is a major factor. I've ruined enough gel cells over the years and gave up on them. My recommendation is use LiFePO4 battery packs, yeah they cost a lot more but they hold a change for months or longer without requiring a trickle charger like Lead Acid. This type of battery doesn't get ruined buy sitting around for long periods partially discharged. Lead Acid types will sulfate ruining the battery.

This topic comes up every once in a while in other threads but not discussed on its own. A number of people got GMRS, and or Ham, radios for use during an emergency but haven't given much thought to how the radio(s) will be powered once the battery pack is dead, for portables, and how to recharge them. For an extended power outage, over a large area, gas powered generators likely won't work for long due to the fact the gas pumps likely won't have power either to refill the gas cans. One case in point was the great northeast power blackout in 2003. https://en.wikipedia.org/wiki/Northeast_blackout_of_2003 I'm in the Detroit area and the gas stations had no power except for a few. Those were only pumping gas for police, fire etc. nothing for anybody else. One solution is using a small solar power system to keep a battery charged up. There are plans all over the Internet for building "solar power generators" with one example below. https://www.builditsolar.com/Projects/PV/PortableSolarGen/easy_diy_solar_generator.pdf Some of the info above is out of date, but the general idea of how to build one isn't. So what plans have people made to power their radio equipment when the grid goes down?

You need to look at EVERYTHING! And even then you may still get burned. You can get some very good equipment and deals on eBay but it takes time and research what you are buying FIRST before spending your money. I was looking at what was advertised as a TK-3170 UHF radio. Some of the photos looked like they were lifted from the manufactures web site, had that "new" look, not what you expect from a "used" radio. Others showed obvious signs of usage. One showed a partial of the rear of the radio which showed the model as a TK-2170 VHF type, which I would not mind getting anyway, so I ordered it. Well it showed up and it was a TK-3170 alright, name plate didn't match the sellers photo, but for the totally useless band spread of 400 MHz to 430 MHz. It was now obvious the seller was completely dishonest in his listing and knew it, not a common mistake where some sellers get the model or description wrong. That's why I like seeing the name plate with serial number, FCC ID and model number. The seller had a 99.8% rating too, but not after I was done with the feedback. I finally got eBay to refund the cost plus shipping. I've purchased plenty of handheld radios off eBay, have a good collection of them, so I know what to look for but still got burned. So if you don't have experience buying used, don't, or have somebody who does look it over and do your research.

If you're referring to me the radios I'm using are Part 95 certified, no modifications, and will accept entry of frequencies in the Ham 70cm band too, the programming software complains with a warning pop-up window but will accept the entry. That's why I use them. TK-370G-1 https://fccid.io/ALH29473110 TK-3170 https://fccid.io/ALH34713110 The FCC grants show Part 95A, among several others, since at the time that was the section for GMRS. When the rules were updated it changed to Part 95E, but that will not invalidate the original grant. You will also notice the grant is for both wide and narrow band too. It seems a lot of the older Kenwood commercial band radios have Part 95 certification. For Amateur Radio the only thing the FCC certifies the radios for is Part 15, making sure the radios can't receive cellular phone frequencies.

One can never have enough radios. 8-) GMRS is a good way for people to test the water and see if they like radio communications without having to do any testing. Good luck getting your Tech Class license. Later you can upgrade to General Class which gives you access to all of the HF bands for world wide communications, very handy if the worse happens and local public communications resources are completely wiped out. Some commercial band radios are FCC certified for Part 95, and the programming software will allow Ham 70cm frequency entries even if they are outside of the "official" range for the radio, the software throws up a warning message, but allows the entry. I've used two so far, both Kenwood radios, TK-370G-1 and the TK-3170. I can get them down to around 440MHz or so which covers the simplex and repeater sections of the Ham 70cm band. Now I only need one radio for both services and its legal since I'm licensed for both. There is one other radio service on VHF that could prove useful too. That's MURS and no license is required. You can find some MURS certified radios out there. https://en.wikipedia.org/wiki/Multi-Use_Radio_Service https://www.intercomsonline.com/murs-radio-multi-use-radio-service-technology-guide

Don’t forget with the change in the rules both GMRS and FRS now share the same frequencies. One of the major differences between them is FRS can’t use repeaters, thus my comment about using simplex, and FRS is narrow band. I have two sets of memories programmed in my radios, one for the wider bandwidth for GMRS, the other for narrow band for FRS.

FCC database search for the Virgin Islands shows only 15 active licensed GMRS users. I didn’t drill down to see who was located where however. If they are spread out over multiple islands your chance of contacting one on the air likely isn’t very high. The chance of contacting someone using a cheap FRS radio, simplex only since they don’t have repeater functions, might be higher. I would also suggest you look at getting at least your Ham Tech class license. That will increase the opportunity of contacting somebody during an emergency. About a third of the group of GMRS users on my local repeater are also licensed Hams.

If you're worried about having communications after a major storm you should also think about a source of emergency power. Last storm through Puerto Rico for example the power was out for a really long time from the reports on the news. After a few days you likely won't find any gas for a generator so a long term solution is needed. You will likely want something like a small solar panel, charge controller and battery. Then look for a 12VDC battery pack eliminator for the radio. I have a few charging cradles for the commercial Kenwood radios, with one modified to use 12 to 14 VDC input, instead of wall outlet power, to recharge the battery pack. If you can't find a 12VDC battery pack eliminator then a few spare battery packs you can cycle through the charger works too.

If GMRS ever allows DMR I would think SFR mode would be the way to go since it would be simple for a user to setup, no fancy controller or cavity filters to deal with. In fact this would be ideal for a Ham buddy that's into off-roading with his Jeep and the group he belongs to. They are switching to GMRS since that seems to be the direction the off-roading community is moving towards. He's trying to get the group members to get their Ham Tech class tickets. If he can do that then using DMR with one radio setup as the repeater using SFR mode would fit exactly what they are looking for without a complex system to drag around. If a particular frequency is busy you just switch to another one. Can't do that in the field with a conventional setup.

DCDM, allows two voice channels on the same frequency. That's good to know. I wasn't aware there are radios that could coordinate the time slot sharing without a repeater in the mix. The question there is how many DMR radios have that capacity? The point about single frequency repeaters using DMR I think is a significant development. It just so happens the CCR's I linked to offer it but I'm not advocating people buy those CCR's, just used them as an example.

I believe that is only true when operating through a DMR repeater. The repeater supplies the sync signal so each radio knows when to transmit based on the time slot selected. When operating simplex there is no sync signal to determine which of the two times slots is slot 1 or slot 2. One of the interesting aspects of DMR is with the right programming of the firmware a radio could supply the sync signal. In the case of the D578UV, from what I've read, can do this thus you can run a single frequency repeater, no offset or tuned cavity filters required. There are some other DMR radios that claim to have the feature as well. https://www.ailunce.com/blog/What%27s-Single-frequency-repeater-function https://www.rexontec.com.tw/en/product/RPT-810.html

You can try the antennas from Ed Fong. He sells several models from base antennas to "roll-up" types for portable use. None require a ground plane so they are ideal for temporary use. For a base type antenna look at this one. "DBJ-1 (commercial) dual band base antenna - (152-157 MHz and 460-470 MHz). Maximum power input 75 watts. - $36" For portable use< roll-up type, this should work. DBJ-2 (commercial) dual band roll up antenna kit - (152-157 MHz and 460-470 MHz). Includes adapters for BNC, SMA and SMA - female. Also includes a 6 ft extension cable. Maximum power input 50 watts. - $36 The link to the website is below. https://edsantennas.weebly.com/ These are "J-Pole" antennas. For some background on what they are a basic theory how they work can be found at the following link. https://en.wikipedia.org/wiki/J-pole_antenna Without seeing your situation a roll-up antenna might be a good choice if you have something nearby to throw a light string or rope over, like a tree limb. Then you just hoist the antenna up by the string, the higher the better. When you're done just drop it down and store it. Likely you can get away with leaving the string in place for next time. Some years back when I lived in a ground floor apartment I used a portable light fiberglass "pushup mast" stuck in a heavy duty speaker tripod. That got a telescoping dual band antenna up about 20 feet. I ran the coax out of the window. This was done at night so as not to attract too much attention. http://www.randl.com/shop/catalog/index.php?manufacturers_id=67&sort=3a&page=20&osCsid=6bcm5d1bpm8b0ar83lvi2h2a40