brettstoner Posted January 12, 2018 Report Share Posted January 12, 2018 Hello,Joined the world of GMRS last month with the purchase of three portables, BTECH GMRS-V1, and NAGOYA NA-701C antennas. So far I am happy with their performance. Mostly going to use them for camping, the kids, and cub scouts. Currently working on installing a repeater on my home roof for better local coverage. TKR-820, Heliax 1/2 hardline, and J-pole antenna. Hope to have it up and running by next weekend. Really curious to see coverage in urban city with 20-25 ft height antenna. May upgrade J-pole antenna to DB404 antenna. Not sure yet.... Brett Hans 1 Quote Link to comment Share on other sites More sharing options...
n4gix Posted January 12, 2018 Report Share Posted January 12, 2018 At that height expect 1 to 2 miles HT, and up to 4 miles mobile. Height is Might!Welcome to the insanity er, hobby! Hans 1 Quote Link to comment Share on other sites More sharing options...
mcallahan Posted January 12, 2018 Report Share Posted January 12, 2018 I'm curious as to why you chose the Nagoya NA-701C antenna to use on the GMRS-V1? That antenna is a dual band VHF/UHF antenna, and I can't imagine it would perform as well as a UHF specific antenna. The stock antenna on the GMRS-V1 I have found to be very excellent. Logan5 and Hans 2 Quote Link to comment Share on other sites More sharing options...
WRAF213 Posted January 13, 2018 Report Share Posted January 13, 2018 I'd assume it works about as well as a Nagoya NA-701 does on 440, which is pretty great. I still prefer dipoles Quote Link to comment Share on other sites More sharing options...
brettstoner Posted January 13, 2018 Author Report Share Posted January 13, 2018 This is cut and paste from Btech website. "The NA-701 is tuned to the amateur frequencies of 144/430MHz (* consider the NA-701C for higher VHF/UHF frequencies 155/455MHz)." So I went with the NA-701C to try it since GMRS is 462-467. I also like how flexible it is with how rough my kids are. Once I get my repeater up (hopefully today) I want to do some experiments with the stock and NA-701C antenna and see performance differences. Right now I am getting about a 1 mile urban range handheld to handheld. I can get 1.5 miles if I am in the right position but it is not reliable. Zero elevation difference. Very flat land. Single story residential neighborhood. I don't have a mobile or base to compare. Right now I have an antenna mount on my roof. If I am not satisfied with performance I may get a TV tower and get up to 35 or 45 ft. Prefer not to get into that investment if I don't have to. Guess we will see.... brettstoner 1 Quote Link to comment Share on other sites More sharing options...
WRAF213 Posted January 13, 2018 Report Share Posted January 13, 2018 A friend of mine put my (not counterfeit) NA-771 on a VNA, resonances were at 151 MHz and 445 MHz. I don't remember the 2:1 VSWR range on VHF, but on 440 it came out to about 431 to 462.9 MHz. The antennas are fairly broadband, but with resonance actually rather close to where they state it is, the NA-701C would work more efficiently when transmitting at 467 MHz. I can't speak for the bandwidth of the NA-701 as I don't own one, but I'd expect it to be a bit wider than the NA-771's. I assume the GMRS-V1 ships with the same antenna as the UV-82. Mine came out resonant somewhere around 505 MHz. It's under 5:1 (maybe even less, I can't remember) at 467 MHz, though. Next time I've got access to the VNA I should do a writeup. Quote Link to comment Share on other sites More sharing options...
brettstoner Posted January 14, 2018 Author Report Share Posted January 14, 2018 Unfortunately I'm not a ham and not very knowledgeable about that. I got my repeater up and running. I get 2 mile range so you guys right on! Seems to be about every 10 feet of height gets you a 1 mile range. Is antenna height everything? Would switching from a jpole to dipole DB404 make any real range difference? Hans 1 Quote Link to comment Share on other sites More sharing options...
n4gix Posted January 14, 2018 Report Share Posted January 14, 2018 Honestly, no. Although it would be a bit taller, that's not enough of a difference to extend your range much. The increase in "gain" only translates to effective radiated power (ERP), not distance. UHF frequencies are effectively "line of sight" with not much if any leakage beyond the horizon, which is not surprisingly known as the "radio horizon". Here is a link to a 'line-of-sight' calculator: http://www.calculatoredge.com/electronics/lineofsight.htm Enter your repeater's antenna height in the first box and assume about 5' height for an HT or mobile radio. You will be surprised at the actual correlation between height of the transmitter antenna and effective range!. These are results for the effective radio horizon for different antenna heights. 30'/5' = 11 miles. 60'/5' = 14 miles 120'/5' = 18 miles 240'/5' = 25 miles 480'/5' = 34 miles Notice that the increase in height of the antenna isn't directly proportional to the effective distance. Doubling the height from 30' to 60' is only a 3 mile increase. It's a case of diminishing returns, especially when comparing the massive increase in the costs of that height! Hans and Logan5 2 Quote Link to comment Share on other sites More sharing options...
brettstoner Posted January 15, 2018 Author Report Share Posted January 15, 2018 Interesting. That makes sense. I have my antenna on the roof of my one story house. I don't have a problem with power, it's line of sight. In fact I have my repeater output level turned about half way. (I don't have a way to measure output) Tried to match input to output. No need to blast 50 watts when I can only hear 5 watts a mile or two out. http://i.imgur.com/nkiBlfs.jpg I think unless I get the antenna up higher than two story houses in the neighborhood there is not much point of going higher because of line of sight. I'm not sure I want to invest in a TV tower yet. brettstoner, Logan5 and Hans 3 Quote Link to comment Share on other sites More sharing options...
n4gix Posted January 15, 2018 Report Share Posted January 15, 2018 Nice job on the repurposing of the old satellite antenna mount. Keeping the power as low as needed is a good thing. There's no point in simply being a "Gator Mouth" with "Cricket Ears" after all... Here is a picture of my roof's antenna farm. The far left is the repeater, the center is my 2m/70cm ham, the two on the chimney mounts are my backup antennas for 2m/70cm and 70cm ham and GMRS. My J-Pole is not visible in this photo: Logan5 1 Quote Link to comment Share on other sites More sharing options...
Hans Posted January 15, 2018 Report Share Posted January 15, 2018 Unfortunately I'm not a ham and not very knowledgeable about that. I got my repeater up and running. For your average bear, that's no small feat. Kudos! Quote Link to comment Share on other sites More sharing options...
brettstoner Posted January 16, 2018 Author Report Share Posted January 16, 2018 Thanks for the words of encouragement. Honestly it wasn't too difficult. I purchased a used TKR-820 from Tim at http://www.thetkrguy.com (which by the way fantastic job, highly recommend). It arrived at my door tuned and ready to plug in and go. Two sets of tones. 141.3 for the public and a private set for my family. I then bought a J-pole and ferrite beads from Michael at http://www.jpole-antenna.com (again also did a great job answering my questions). Purchased 50 feet of Heliax 1/2 hardline and connectors. I use to have a 900 MHz Yagi antenna for a cell phone repeater which I took down off the old Dish satellite mount. I had 1.5 PVC extending it 5ft and #4 copper running to ground. Mounted the J-Pole, weatherseal the connector, and run the Heliax down the roof and wall and into the basement. Hard part was worrying about not falling off the roof due to the snow and ice. Very slippery. I still have the LMR-400 from the old Yagi I need to take down once the weather warms up. I then went out 2 miles and adjusted the repeater output until it was loud enough to match my handheld. I finally got a chance this afternoon to do some testing and sound quality was great. I had two goal locations, one at 1.5 miles and one at 2 miles, and both come through very clear on 5w handhelds while indoors at both locations. I see no need to upgrade antennas or get higher for more range at this time. I am happy with the performance. This is a setup for family at 3 houses. I never realized how much height played a role. I was smart enough to realize the bubble pack claims are ridiculous but in an urban residential city I was only getting a mile with my 5w handhelds. Even now with my repeater on my roof I am only getting a little over two miles. And this is all very flat land with zero elevation change. Logan5 and Hans 2 Quote Link to comment Share on other sites More sharing options...
brettstoner Posted January 16, 2018 Author Report Share Posted January 16, 2018 Nice job on the repurposing of the old satellite antenna mount. Keeping the power as low as needed is a good thing. There's no point in simply being a "Gator Mouth" with "Cricket Ears" after all... Here is a picture of my roof's antenna farm. The far left is the repeater, the center is my 2m/70cm ham, the two on the chimney mounts are my backup antennas for 2m/70cm and 70cm ham and GMRS. My J-Pole is not visible in this photo: What kind of antenna is the GMRS repeater? Quote Link to comment Share on other sites More sharing options...
n4gix Posted January 16, 2018 Report Share Posted January 16, 2018 What kind of antenna is the GMRS repeater?It is a Comet CA-712EFC 9dB gain fiberglass antenna. Seventy feet of 1/2" heliax feeds the Bridgecom BCR-40U repeater. Here is a picture of it assembled and with the joint sealed with shrink tube prior to installation. Hans, Logan5 and brettstoner 3 Quote Link to comment Share on other sites More sharing options...
Soladaddy Posted January 22, 2018 Report Share Posted January 22, 2018 I've found my range jumps after clearing the roofs of the nearby houses at about 25 ft. Now if I can clear the tree tops near 45 ft, then range should bump up again. But I can see the appeal for short distance if the audience is covered. How do you like the j-pole? Was just looking at his offerings and the prices are not bad. Quote Link to comment Share on other sites More sharing options...
brettstoner Posted January 24, 2018 Author Report Share Posted January 24, 2018 I've found my range jumps after clearing the roofs of the nearby houses at about 25 ft. Now if I can clear the tree tops near 45 ft, then range should bump up again. But I can see the appeal for short distance if the audience is covered. How do you like the j-pole? Was just looking at his offerings and the prices are not bad. I could believe it! I have my antenna on the roof of my one story. Although my neighborhood is mostly 1 story ranch there are many 2 stories in the area that I am trying to go through. I like the J-pole. It works for my needs and I am getting the range I want.... and the price was very attractive! Is it better or worse than commercial antennas.... I honestly have no idea. I am not knowledgeable enough on antenna theory and design. I did paint mine grey to blend in with the sky. Probably the only downfall is that it looks different verse traditional antennas so it might stick out more. Having the large black cable coming out the side also makes it more noticeable. It doesn't bother me and none of my neighbors notice it so in the big scheme of things it is insignificant. Brett Quote Link to comment Share on other sites More sharing options...
Recommended Posts
Join the conversation
You can post now and register later. If you have an account, sign in now to post with your account.
Note: Your post will require moderator approval before it will be visible.