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#1
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heliax vs lmr
i've read the specs on some healiax and lmr 400 but i can't say that i
always can interpert it fully and confused myself basically interperting a real world practical answer if for ex i am going to do some 1296 work and debate what coax is best i compare lmr400 to 1/2i heliax is the heliax much better ? by how much how about lmr 600 vs 1/2in/ and maybe 7/8" heliax is the lmr nearly as good or is the heliax vastly superior? comming here for a tie breaker everyone i asked either gives different answers and non can explain their choice i am not looking for a well lmr is pretty close and cheeper so buy it, price is not the issue i just want to know based on technical spec's if they are only 1db apart it's splitting hairs i'd get the cheepest easist to work w/ after that i just want least loss thanks |
#2
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heliax vs lmr
The problem you are having comparing heliax to coax is that you are not considering all the parameters. Loss is only one aspect. The biggest difference between most coax and Heliax is physical construction. Heliax, properly installed, with last 10 to even 20 years outdoors before it should be replaced. Coax would deteriorate much much faster. Heliax is a much more "sturdy" product and can also hold up to weather damage better than coax. Being made with a sold jacket also adds to its shielding superiority over most coaxial cables. For most ham use, You'll get the performance you need with coax type cables and not need heliax.... plus your wallet will remain fatter, too. ( I haven't even mentioned the high cost of connectors for Heliax, if you purchase them new.) Ed K7AAT |
#3
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heliax vs lmr
No doubt you'll get a few answers...
This is a good URL to compare line loss on; http://www.ocarc.ca/coax.htm A 50 metre run on 1296 of LMR400 is about 7.8dB A 50 metre run of LDF4-50 (1/2" heliax) is about 4.2dB A 50 metre run of LDF5-50 (7/8" heliax) is about 2.3dB You can work out the difference in your install by scaling things proportionally. Dont forget to factor in additonal loss for any mismatch. You then have to ask whether that few dB will make a difference in whatever your mode of operation and interest is. When a RX signal is borderline that dB or two can make a useful difference. Dont forget to factor in the cost of connectors. You may also find both the LMR400 and Andrew cable is too rigid. I'd personally stick to LMR400 simply because I see that as a major step up from (say) RG213 (16dB loss per above) using roughly the same cable diameter. Some of my interest is in low signal 144MHz work but I tend to reduce that problem by using a preamp at the antenna. About the only downside for me using LMR400 is its rigidity and turn radius limitation. I also tend to think in terms of a link budget. Thats easy to do with a path prediction program. (There are some GPL ones out there) Hope this helps Cheers Bob VK2YQA ml wrote: i've read the specs on some healiax and lmr 400 but i can't say that i always can interpert it fully and confused myself basically interperting a real world practical answer |
#4
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heliax vs lmr
In article ,
Bob Bob wrote: No doubt you'll get a few answers... This is a good URL to compare line loss on; http://www.ocarc.ca/coax.htm A 50 metre run on 1296 of LMR400 is about 7.8dB A 50 metre run of LDF4-50 (1/2" heliax) is about 4.2dB A 50 metre run of LDF5-50 (7/8" heliax) is about 2.3dB You can work out the difference in your install by scaling things proportionally. Dont forget to factor in additonal loss for any mismatch. You then have to ask whether that few dB will make a difference in whatever your mode of operation and interest is. When a RX signal is borderline that dB or two can make a useful difference. Dont forget to factor in the cost of connectors. You may also find both the LMR400 and Andrew cable is too rigid. I'd personally stick to LMR400 simply because I see that as a major step up from (say) RG213 (16dB loss per above) using roughly the same cable diameter. Some of my interest is in low signal 144MHz work but I tend to reduce that problem by using a preamp at the antenna. About the only downside for me using LMR400 is its rigidity and turn radius limitation. I also tend to think in terms of a link budget. Thats easy to do with a path prediction program. (There are some GPL ones out there) Hope this helps Cheers Bob VK2YQA ml wrote: i've read the specs on some healiax and lmr 400 but i can't say that i always can interpert it fully and confused myself basically interperting a real world practical answer thanks very much i see the 600 and 1/2 are very close and the 600 is way chubby and hard to work w/plus $$ whereas heliax i think i can find on ebay or hamfair normal sized guess it will last has good shield not too bad to work w/ i think in my applicatioin a 1'x1' shaft few bends on the roof easy and a few in the hallway molding tray prob the hard part not counting hoisting it up the shaft the lmr went up ok but it's light adding more coax and antennas are the most fun thanks again al for the help |
#5
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heliax vs lmr
In article . 196,
Ed wrote: The problem you are having comparing heliax to coax is that you are not considering all the parameters. Loss is only one aspect. The biggest difference between most coax and Heliax is physical construction. Heliax, properly installed, with last 10 to even 20 years outdoors before it should be replaced. Coax would deteriorate much much faster. Heliax is a much more "sturdy" product and can also hold up to weather damage better than coax. Being made with a sold jacket also adds to its shielding superiority over most coaxial cables. For most ham use, You'll get the performance you need with coax type cables and not need heliax.... plus your wallet will remain fatter, too. ( I haven't even mentioned the high cost of connectors for Heliax, if you purchase them new.) Ed K7AAT lots of good tips everyone thanks much |
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