Radioactive Posted October 26 Report Share Posted October 26 I live in East Tennessee. Hilly/mountainous terrain. A couple years ago I was trying out a retevis portable gmrs repeater, and I had it connected to a commercially built gmrs antenna. I was utterly dissapointed, getting only around 3 miles range. The antenna was only up about 15 feet, in a residential neighborhood so I assumed that was that. I had a couple years prior purchased a surecom simplex repeater thinking I could use it for various things, including testing range of radios etc. So, awhile back I bought a Jpole gmrs antenna from kb9vbr antennas, it arrived and I never got around to erecting it until yesterday. I mounted it to a section of chain link toprail and connected that to another section of top rail, giving me about 20' elevation for the antenna. Today I set up the simplex repeater, just tinkering around really, but had to go on an errand so I thought I would see what it could do. I have to go over a good sized hill to get to the highway from my house, so when I got to the top of the hill I gave it a try, loud and clear, no surprise there really as its really close to home and with all that elevation I expected nothing less. But then when I got to the bottom of the hill, I tried again, and again it was loud and clear. I was intriqued. So a half mile up the road or so I keyed up, and to my surprise it was nice and clear. Did this at several spots, each time getting a nice clear reply. Each time thinking theres no way it will reach this far. Finally it did fail to repeat, but not until I was almost 10.5 (10.47 measured with google earth straight line)miles away from it as the crow flies, NOT road miles mind you, I was and am IMPRESSED!! I intend to set up my duplex retevis repeater next on the antenna, as this is a really useful range at long last!! warthog74 and SteveShannon 2 Quote Link to comment Share on other sites More sharing options...
Socalgmrs Posted October 26 Report Share Posted October 26 Nice. Just wait untill you get a good antenna up. The you will really start to gain milage. gortex2 1 Quote Link to comment Share on other sites More sharing options...
SteveShannon Posted October 26 Report Share Posted October 26 42 minutes ago, Radioactive said: I live in East Tennessee. Hilly/mountainous terrain. A couple years ago I was trying out a retevis portable gmrs repeater, and I had it connected to a commercially built gmrs antenna. I was utterly dissapointed, getting only around 3 miles range. The antenna was only up about 15 feet, in a residential neighborhood so I assumed that was that. I had a couple years prior purchased a surecom simplex repeater thinking I could use it for various things, including testing range of radios etc. So, awhile back I bought a Jpole gmrs antenna from kb9vbr antennas, it arrived and I never got around to erecting it until yesterday. I mounted it to a section of chain link toprail and connected that to another section of top rail, giving me about 20' elevation for the antenna. Today I set up the simplex repeater, just tinkering around really, but had to go on an errand so I thought I would see what it could do. I have to go over a good sized hill to get to the highway from my house, so when I got to the top of the hill I gave it a try, loud and clear, no surprise there really as its really close to home and with all that elevation I expected nothing less. But then when I got to the bottom of the hill, I tried again, and again it was loud and clear. I was intriqued. So a half mile up the road or so I keyed up, and to my surprise it was nice and clear. Did this at several spots, each time getting a nice clear reply. Each time thinking theres no way it will reach this far. Finally it did fail to repeat, but not until I was almost 10.5 (10.47 measured with google earth straight line)miles away from it as the crow flies, NOT road miles mind you, I was and am IMPRESSED!! I intend to set up my duplex retevis repeater next on the antenna, as this is a really useful range at long last!! In hilly terrain is where something like the j-pole will really shine. Good job! WRYZ926, Radioactive and Raybestos 2 1 Quote Link to comment Share on other sites More sharing options...
WRYZ926 Posted October 26 Report Share Posted October 26 There is nothing wrong with a good j-pole antenna. And @SteveShannon is correct, a j-pole antenna or any other antenna with 5-6 dB of gain will work better in hilly terrain compared to antennas with 9 dB of gain. The higher the gain is, the flatter the radiation lobe is. Think of it as a balloon. If you push on it to flatten it, you get a stronger signal but it will be narrower. When it comes to antenna designs, what matters is that it is resonant on the frequencies you are transmitting on. A simple dipole or even a vertical j-pole made from coax or electrical wire will work just fine. Getting the antenna resonant and at the right impedance of 50 ohms is what matters. I know plenty of people that use electrical wire or old coax to make j-pole antennas for UHF and GMRS. They get out just fine with those home made antennas. Radioactive and SteveShannon 2 Quote Link to comment Share on other sites More sharing options...
warthog74 Posted October 26 Report Share Posted October 26 11 hours ago, Radioactive said: I bought a Jpole gmrs antenna from kb9vbr I am using that same GMRS tuned j-pole for my repeater. It's up on a 50 foot mast. Works great. Radioactive and JBRPong 1 1 Quote Link to comment Share on other sites More sharing options...
WRUE951 Posted October 26 Report Share Posted October 26 i had a homemade J-Pole on my portable RV repeater set up and was always impressed with it.. Then for some reason i decided to try a Midland MXA w/ground plane kit.. Although always afraid to admit it, my home brew J-pole performed better and about $160 bu bucks cheaper.. I also get better SWR with the J-Pole and probably why it performs better.. Radioactive 1 Quote Link to comment Share on other sites More sharing options...
WRZR953 Posted October 26 Report Share Posted October 26 Good To hear since Ive just recieved one of these. All new to me. Trying to figure out mounting solutions and coax type vs length. Radioactive 1 Quote Link to comment Share on other sites More sharing options...
SteveShannon Posted October 26 Report Share Posted October 26 14 hours ago, Socalgmrs said: Just wait untill you get a good antenna up. Why do you say dumbass judgemental things like that to people? What’s wrong with you? Radioactive and WRYZ926 1 1 Quote Link to comment Share on other sites More sharing options...
Radioactive Posted October 26 Author Report Share Posted October 26 43 minutes ago, WRZR953 said: Good To hear since Ive just recieved one of these. All new to me. Trying to figure out mounting solutions and coax type vs length. I attached mine to a section of chain link toprail with the clampa it came with, and using 25' of some lmr 400 "like" coax from amazon. Works great. The shorter the coax you can use the better. 462mhz is has high loss so the type and length of cable matter alot. Good luck! WRYZ926 and SteveShannon 2 Quote Link to comment Share on other sites More sharing options...
WRZR953 Posted October 26 Report Share Posted October 26 Arent you supposed to make a 4 inch loop somewhere near the top of the coax ? Mine Came with some instructions reccomending this whic are not on front of me atm. I was curious about doing this and how it would be accomplished with the thicker lmr 400 or if you need a piece of thinner coax to start with .. Quote Link to comment Share on other sites More sharing options...
SteveShannon Posted October 26 Report Share Posted October 26 28 minutes ago, WRZR953 said: Arent you supposed to make a 4 inch loop somewhere near the top of the coax ? Mine Came with some instructions reccomending this whic are not on front of me atm. I was curious about doing this and how it would be accomplished with the thicker lmr 400 or if you need a piece of thinner coax to start with .. A drip loop near where you go through your wall is helpful to keep water out of your walls, but that’s at the other end of the coax. For some antennas a loop is added next to the antenna to act as a choke. The minimum radius allowed for lmr400 might not allow that. If you think you need a choke you can make on with a more flexible cable, like rg58. It’s such a short length that the losses won’t hurt. There’s really no other reason for a loop at the antenna end as far as I know. I doubt that you need it. Quote Link to comment Share on other sites More sharing options...
WRZR953 Posted October 26 Report Share Posted October 26 Seems after some research. The antenna manufacturer was referring to a choke to keep rf out of the feed line. An Alternative with lmr 400 could be ferrite snap ons I suppose. Thanks for your input. So much to learn and consider. SteveShannon 1 Quote Link to comment Share on other sites More sharing options...
WRYZ926 Posted October 26 Report Share Posted October 26 Another reason to have a loop at the antenna end is so that you have some slack in the coax in case you ever have to work on the antenna. I generally try to leave one wrap right at the antenna for this very reason. One or two wraps in a coil will not work very well for a common mode choke. It takes a certain number of wraps and they need to be a certain size to make an effective choke. Quote Link to comment Share on other sites More sharing options...
WRWE456 Posted October 26 Report Share Posted October 26 KB9VBRr antennas recommends and sells the snap on ferrite chokes for the J-pole he sells. https://www.jpole-antenna.com/shop/snap-on-ferrite-beads-11mm-set-of-3/ I got them for mine when I ordered it and they are the correct size for LMR 400 and RG8-U. Be sure and wrap them with electrical tape so they don't slide. Quote Link to comment Share on other sites More sharing options...
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