WRXX938 Posted August 20, 2023 Report Posted August 20, 2023 I am looking to set up a simple base system. I have a good repeater 4 Miles away and 3 or 4 that are just out of reach for my uv5r. This is my plan so far. https://www.amazon.com/gp/aw/d/B0BNLT88FD/ref=ox_sc_saved_image_5?smid=AA3MGRC7F9EI2&psc=1 https://www.amazon.com/gp/aw/d/B0B38Q81NC/ref=ox_sc_saved_image_1?smid=A2NBMQOC5OUPR&psc=1 I would like suggestions for decent priced antenna and power supply. I also have coax questions. Is the link above an ok option for coax? I am a cable Tech and can get rg7 and rg11 cable. I don't suppose this would work in any way? Mostly because of the connectors I suppose? O know nothing comes cheap but... I have too many hobbies so functional but budget friendly options please. Thanks, AL Quote
WRQC527 Posted August 20, 2023 Report Posted August 20, 2023 Use 50 ohm coax like RG58, RG8X, etc with PL259 connectors. RG7 and RG11 are 75 ohm and have the wrong connectors. As for the radio, nothing wrong with the ones you linked. There's lots of switching power supplies out there. Samlex, Powerwerx, MFJ, etc. Make sure you get one that puts out enough amps to supply the radio on high power. I use a 35 ah AGM battery on a battery maintainer to power my radios, so that's another option that will give you some run time if the power is out. Quote
SteveShannon Posted August 20, 2023 Report Posted August 20, 2023 1 hour ago, WRQC527 said: Use 50 ohm coax like RG58, RG8X, etc with PL259 connectors. RG7 and RG11 are 75 ohm and have the wrong connectors. Unfortunately these two sentences pass along bad information. I’ll take them separately: Yes, it’s generally best to use feedline that matches the impedance of the radio, but swapping a minor impedance mismatch has fewer disadvantages than using RG-58 or 58x which has incredibly high attenuation at GMRS frequencies. Using 75 ohm feedline with a 50 ohm radio simply means that you start with a theoretical SWR of 1.5. That’s not terrible and PL-259 connectors are available for both of the common 75 ohm cables. So are adapters. RG-11 attenuates RF in the 400 MHz range at the rate of 3.5 dB per 100 feet. That’s a little more than half of your power lost in the cable. RG-58 attenuates RF in the 400 MHz range at the rate of 11.2 dB. That’s more than 90% of your power lost. I wouldn’t use RG-58 for GMRS feedline for anything longer than 10 feet. https://www.w4rp.com/ref/coax.html WRXB215 and WRUU653 1 1 Quote
WRUU653 Posted August 20, 2023 Report Posted August 20, 2023 @Sshannon thank you for the charts. SteveShannon 1 Quote
labreja Posted August 20, 2023 Report Posted August 20, 2023 Being relatively new to GMRS and ham radio, the most important things that I have learned is, in my opinion is, use the best coax you can afford. Use that coax to feed the best antenna you can afford. I use LMR400 coax with good results. Here are a couple of links to some antennas I use. The Ed Fong is what I currently use for a base antenna. The n9taxlabs antenna I use when camping. https://www.kbcubed.com/DBJ-UHF-5dB-GMRS-Antenna-by-Ed-Fong-p379488596DBJ-UHF-5dB-GMRS-Antenna-by-Ed-Fong-p379488596DBJ-UHF-5dB-GMRS-Antenna-by-Ed-Fong-p379488596DBJ-UHF-5dB-GMRS-Antenna-by-Ed-Fong-p379488596DBJ-UHF-5dB-GMRS-Antenna-by-Ed-Fong-p379488596DBJ-UHF-5dB-GMRS-Antenna-by-Ed-Fong-p379488596 https://n9taxlabs.com/shop/ols/products/dual-band-murs-gmrs-slim-jim-with-10-or-16-foot-cable Lastly, I run Kenwood TK-880-1 ver2 radios. One in my wife's car, one in the truck and one as a base. They are pretty inexpensive, easy to program and built like tanks. I hope this helps. Quote
BoxCar Posted August 20, 2023 Report Posted August 20, 2023 For your installation, you will be better served using quality coax like LMR-400. RG-8 and most variants are best at frequencies below 60 MHz. For a power supply, the Mean Well (also Meanwell) is an excellent unit. A 30A supply in the LMR series will provide all the power and filtering you'll need. For an antenna, the key point is higher is better - and that is elevation, not gain. J-poles are adequate and cheap. The better J-poles are copper tubing, not twin lead like the Ed Fong antennas. There isn't anything wrong with an Ed Fong, it's just there are better ones out there. Quote
WRXX938 Posted August 20, 2023 Author Report Posted August 20, 2023 Anyone got a link to a coax source for LMR400? Only need about 50 feet. Also I thought about building a J pole myself. I can handle the connections just fine, but the parts sizes is what I need the info on. I also thought a bought antenna would be better. I live on a decent hill and have a pretty good line of sight from the ground. The plan is to put an antenna about 8 feet off the roof peak. I have a dish tripod that I can put a pole on almost as long as I want. I could even add wire guide lines if I wanted to go . I have use of a bucket truck. Thanks guys, AL Quote
UncleYoda Posted August 20, 2023 Report Posted August 20, 2023 Browse or Use their Custom Cable builder: https://mpddigital.us/ Or this: https://thewireman.com/product/cq-rg8-low-loss-4xl-lmr400-equivalent/ (The Wire Man sells at a lot of hamfests (not sure about all parts of the US). Quote
WRXX938 Posted August 21, 2023 Author Report Posted August 21, 2023 6 hours ago, Sshannon said: Unfortunately these two sentences pass along bad information. I’ll take them separately: Yes, it’s generally best to use feedline that matches the impedance of the radio, but swapping a minor impedance mismatch has fewer disadvantages than using RG-58 or 58x which has incredibly high attenuation at GMRS frequencies. Using 75 ohm feedline with a 50 ohm radio simply means that you start with a theoretical SWR of 1.5. That’s not terrible and PL-259 connectors are available for both of the common 75 ohm cables. So are adapters. RG-11 attenuates RF in the 400 MHz range at the rate of 3.5 dB per 100 feet. That’s a little more than half of your power lost in the cable. RG-58 attenuates RF in the 400 MHz range at the rate of 11.2 dB. That’s more than 90% of your power lost. I wouldn’t use RG-58 for GMRS feedline for anything longer than 10 feet. https://www.w4rp.com/ref/coax.html So if I only used the RG11 about 35 feet I would have about 1.6 to 1.7 loss? So theoretically if my antenna had a 3.5 gain with 100 feet of rg11 it would be a wash? Please forgive the ignorance on the topic. I really just want it to function. I am not really into the technical stuff. Quote
SteveShannon Posted August 21, 2023 Report Posted August 21, 2023 2 hours ago, WRXX938 said: So if I only used the RG11 about 35 feet I would have about 1.6 to 1.7 loss? So theoretically if my antenna had a 3.5 gain with 100 feet of rg11 it would be a wash? Please forgive the ignorance on the topic. I really just want it to function. I am not really into the technical stuff. Let’s say you have 30 watts at the SO-239 on the radio. Then you have the impedance mismatch so a certain amount is reflected back into the radio. That leaves 20 watts going in the direction of the antenna. Then you have a loss of 1.7 dB, which is about 30% of the 20 watts that’s lost. So you’re down to about 12 watts. I’m estimating rather than calculating so these are pretty sloppy numbers. You don’t say whether the antenna gain is dBi or dBd. Assuming the best you’ll have about the same RF in certain directions as 25 watts in an isentropic antenna (it really is only 12 watts, but in some directions the RF field will be as strong as a 25 watt signal into an antenna with no gain. WRXB215 1 Quote
nokones Posted August 21, 2023 Report Posted August 21, 2023 > Anyone got a link to a coax source for LMR400? Only need about 50 feet. Pasternack or Show Me Cables. Quote
WRXX938 Posted August 21, 2023 Author Report Posted August 21, 2023 1 hour ago, Sshannon said: Let’s say you have 30 watts at the SO-239 on the radio. Then you have the impedance mismatch so a certain amount is reflected back into the radio. That leaves 20 watts going in the direction of the antenna. Then you have a loss of 1.7 dB, which is about 30% of the 20 watts that’s lost. So you’re down to about 12 watts. I’m estimating rather than calculating so these are pretty sloppy numbers. You don’t say whether the antenna gain is dBi or dBd. Assuming the best you’ll have about the same as 25 watts into the antenna (it really is only 12 watts, but in some directions the RF field will be as strong as a 25 watt signal into an antenna with no gain. So LMR400 it is! Thank you! Quote
OffRoaderX Posted August 21, 2023 Report Posted August 21, 2023 I got my 50FT of LMR400, pre-cut with ends on it from Amazon.. Was delivered the next morning. SteveShannon, WRUU653 and WRXB215 3 Quote
BoxCar Posted August 21, 2023 Report Posted August 21, 2023 We had a recent presentation at one of the ham clubs I belong to on using a VNA. The presenter stated just for grins he measured some of the coax he had around the shack. He specifically stated he checked two different cables marketed as LMR-400 equivalent. One failed to meet the published specification for LMR-400 and the other was slightly better than published. The cable that passed had the cable manufacturer's name on it while the poorer cable didn't say who manufactured it. The one he had that passed was from The Wireman. Quote
SteveShannon Posted August 21, 2023 Report Posted August 21, 2023 DXengineering will assemble cable to any length. There’s no point in buying and using a 50 foot cable if 10 feet will just be coiled up somewhere. Ham Radio Outlet, DX Engineering, and Gigaparts all have sales to mark the Huntsville Hamfest. They all have good quality cable and probably carry Times Microwave. For long cable I use Messi and Paloni 10 mm. They have a few different types. All are good. Most have stranded copper center conductors, except for Airborne, which uses copper clad aluminum center conductor for weight. True LMR400 uses a copper clad aluminum center conductor and copper braid over aluminum foil as it’s shield. M&P uses copper braid over copper foil for shield. True LMR400 comes from Times Microwave. I also have jumpers from ABR400. Buytwowayradios.com has good pricing for M&P cable and a good assortment. For whatever reason Gigaparts has a lot of “out of stock” selections for M&P. Quote
PA141 Posted August 21, 2023 Report Posted August 21, 2023 Get ready for sticker shock with Pasternack. ABR Industries is a good US made equivalent to the genuine Times Microwave LMR400. You can purchase directly or from most of the ham radio dealers listed previously. https://abrind.com/cable-overview-abr400-pn24400-2/ SteveShannon 1 Quote
SteveShannon Posted August 21, 2023 Report Posted August 21, 2023 5 minutes ago, PA141 said: Get ready for sticker shock with Pasternack. ABR Industries is a good US made equivalent to the genuine Times Microwave LMR400. You can purchase directly of from most of the ham radio dealers listed previously. https://abrind.com/cable-overview-abr400-pn24400-2/ Yeah, Pasternak has every kind of connector ever made, but their pricing is extremely high. I use them as a reference only. Quote
nokones Posted August 24, 2023 Report Posted August 24, 2023 Pasternack prices are probably the result of doing business in California. They are probably being surcharged to death by the local and governmental regulatory agencies. Quote
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