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Electronics Repair (sci.electronics.repair) Discussion of repairing electronic equipment. Topics include requests for assistance, where to obtain servicing information and parts, techniques for diagnosis and repair, and annecdotes about success, failures and problems. |
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#1
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Which coax is better?
I never remember the numbers, so i will just describe it.
CB and low power ham radios use one type. TV antennas use the other. Both coax is about the same diameter and looks alike on the outside. I have a police scanner. It has an ext. antenna connector on the rear that is one of those "Motorola jacks" (same as the ant. connectors on car radios). I used to use a CB (car type) antenna on my roof, for the scanner. It used the CB coax with them big connectors on the end. When I moved, that antenna got left behind. I recently dug out that scanner again, and have it connected to my homemade weather radio outside antenna. But this weather antenna has the TV style coax with F connectors. I dont yet have an adaptor for F connector to the Motorola jack, but found one on ebay and am waiting for it to arrive. My question is whether it matters which coax is used? My weather radio works fine as it is. I did try the scanner using alligator clips to connect the antenna and i do get a signal. I dont know how well that antenna, made specifically for 162.xx mhz will work on the UHF scanner bands, but I have gotten 155.xx VHF signals well, even with the alligator clip mess..... |
#2
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Which coax is better?
On Friday, 15 March 2019 08:24:00 UTC, wrote:
I never remember the numbers, so i will just describe it. CB and low power ham radios use one type. TV antennas use the other. Both coax is about the same diameter and looks alike on the outside. I have a police scanner. It has an ext. antenna connector on the rear that is one of those "Motorola jacks" (same as the ant. connectors on car radios). I used to use a CB (car type) antenna on my roof, for the scanner. It used the CB coax with them big connectors on the end. When I moved, that antenna got left behind. I recently dug out that scanner again, and have it connected to my homemade weather radio outside antenna. But this weather antenna has the TV style coax with F connectors. I dont yet have an adaptor for F connector to the Motorola jack, but found one on ebay and am waiting for it to arrive. My question is whether it matters which coax is used? My weather radio works fine as it is. I did try the scanner using alligator clips to connect the antenna and i do get a signal. I dont know how well that antenna, made specifically for 162.xx mhz will work on the UHF scanner bands, but I have gotten 155.xx VHF signals well, even with the alligator clip mess..... 50 & 75 ohm. Each is optimised for its own job. Loss & power handling differ, and there's impedance matching to what you're using. There's also wide variation in frequency response with co-ax, some is only good for baseband. Some is well screened, some less so. NT |
#4
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Which coax is better?
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#6
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Which coax is better?
On Fri, 15 Mar 2019 03:23:53 -0500, wrote:
CB and low power ham radios use one type. RG-58c/u TV antennas use the other. RG-6/u (usually good stuff) RG-59a/u (which is garbage) Both coax is about the same diameter and looks alike on the outside. I use RG-6/u with F-connectors for EVERYTHING, whether it's 50 or 75 ohms. I also have a fair collection of Type-F to BNC or PL-259. The mismatch loss is negligible: https://www.qsl.net/n9zia/wireless/75_ohm_hardline.html Please note that there are variations in RG-6/u quality varying from Radio Shack junk to "satellite TV" grade with lower losses at 1GHz frequencies. Some variations are more flexible than others, some have a UV resistant jacket, and some use CCA (copper clad alumunium) which is cheap junk. Caveat emptor. -- Jeff Liebermann 150 Felker St #D http://www.LearnByDestroying.com Santa Cruz CA 95060 http://802.11junk.com Skype: JeffLiebermann AE6KS 831-336-2558 |
#7
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Which coax is better?
On Friday, 15 March 2019 13:11:36 UTC, Fox's Mercantile wrote:
On 3/15/19 3:23 AM, wrote: I never remember the numbers, so i will just describe it. CB and low power ham radios use one type. TV antennas use the other. Communication radios tend to use 50 ohm coax. RG-58 1/4", RG-8X 5/16" and RG-8 RG-213 1/2" (Roughly) TV and most CCTV stuff use 75 ohm coax. RG-59 and RG-6 5/16" and RG-11 1/2" Both coax is about the same diameter and looks alike on the outside. The 75 ohm is noticeably thicker. I have a police scanner. It has an ext. antenna connector on the rear that is one of those "Motorola jacks" (same as the ant. connectors on car radios). My question is whether it matters which coax is used? It doesn't make much if any difference. Don't let people wind you up about impedance matching on receive antennas. Co-ax impedance is not critical, but choosing rf rather than baseband co-ax is. I dont know how well that antenna, made specifically for 162.xx mhz will work on the UHF scanner bands Generally, UHF is 3 times the VHF frequencies. What looks like a 1/4 wave whip antenna (16-18")on VHF will look like 3/4 wave on UHF. And will work just fine. Try it & see. NT |
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