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How important is Coax..length and size?
- Thread starter Mr. Doug
- Start date
B
BOOTY MONSTER
Guest
it depends on the length of the run , the ammount of power , the frq. .
i just ordered 50 foot of 8x for my base im geting together from sparkys . for my short run and only several hundred watts its more than adaquate for cb and export radios , IMO . but if ya got the bucks or a long run or a lot of power lmr-400,9913f7 and bury-flex should all do a fine job . next up the ladder is hardline from what i understand . good quality 259s and PROPER attachment is very important for any coax to perform to its potiental .
good read here .
Welcome to KØBG's Web Site
scroll to ... " Coax & PL259s"
i just ordered 50 foot of 8x for my base im geting together from sparkys . for my short run and only several hundred watts its more than adaquate for cb and export radios , IMO . but if ya got the bucks or a long run or a lot of power lmr-400,9913f7 and bury-flex should all do a fine job . next up the ladder is hardline from what i understand . good quality 259s and PROPER attachment is very important for any coax to perform to its potiental .
good read here .
Welcome to KØBG's Web Site
scroll to ... " Coax & PL259s"
If you are working a legal CB, low power, and modest lengths it has been my experience that the coax is probably a lot less important that most will tell you. The coax is very important, with long lengths, at higher frequencies, or with high power. Of course all your coax should be in good condition and the assembled parts should be installed properly.
I know I will get a lot of arguments with these words, but at the time some years ago we were not that big on meter readings. What counted was---could we reach and hear what all the others around us did.
I had an old 105' RG8x line that had been contiminated by water hooked up to and old Hygain CLRII that had be up for 5-8 years. Later I used the line on my Starduster and when I finally took the line down I tested it. Using a metered dummy load I could put 4 watts in and would see less than 1 watt out at the other end. While it was on the SD'r I was still able to communicated right up there with all my buddies. That is why I worked it for over a year on the SD'r before I discovered the problem. Maybe I did not make much of a signal, but I could talk to and hear everybody the guys around me did---locally or DX.
Technically, there is a difference, but I'm not sure you can tell just by hearing. You might notice a small difference in signal, but as I said above I never noticed a difference that would stop me or allow me to communicate local or DX. If I did there was something else wrong. You will hear guys tell you that when they changed to a new/better, the latest, and greatest feed line---that they could not hear half as far as before or now they can hear the guys in the next town.
Mr. Doug,
It's either very important, or makes no difference at all.
If the characteristic impedance of that coax is the same as the rest of the system, or at least close, it makes very little difference as far as the characteristic impedance goes. So, select a coax of the right impedance.
Power handling ability. It actually amounts to voltage handling ability, how much before the stuff arcs over, or get's too hot? High SWR, or impedance mismatches can raise the voltage to really, really high levels. Only part of that applies to the actual power put into the stuff. More is better to an extent determined only by you.
Losses. All coax has losses. Those losses are determined by frequency of use and length, for any particular size/type of coax. Until those losses get to something like 3 dB, you will never know it or hear it without using 'lab' grade testing equipment. If you are talking about 1 dB of loss, or a fraction of a dB, forget it. RG-58 coax has a bad reputation, but it's only because it was used beyond it's capabilities. The same can be said for ANY coax if it's used beyond it's capabilities. Knowing what those capabilities are certainly helps. At HF, most of the 'high end' coax is vastly over rated. Doesn't hurt to use it, but it's certainly not nece$$ary for the average person. Suit yourself.
None of this tells you exactly what to use, does it? Nope, you need to evaluate that for your $elf.
- 'Doc
It's either very important, or makes no difference at all.
If the characteristic impedance of that coax is the same as the rest of the system, or at least close, it makes very little difference as far as the characteristic impedance goes. So, select a coax of the right impedance.
Power handling ability. It actually amounts to voltage handling ability, how much before the stuff arcs over, or get's too hot? High SWR, or impedance mismatches can raise the voltage to really, really high levels. Only part of that applies to the actual power put into the stuff. More is better to an extent determined only by you.
Losses. All coax has losses. Those losses are determined by frequency of use and length, for any particular size/type of coax. Until those losses get to something like 3 dB, you will never know it or hear it without using 'lab' grade testing equipment. If you are talking about 1 dB of loss, or a fraction of a dB, forget it. RG-58 coax has a bad reputation, but it's only because it was used beyond it's capabilities. The same can be said for ANY coax if it's used beyond it's capabilities. Knowing what those capabilities are certainly helps. At HF, most of the 'high end' coax is vastly over rated. Doesn't hurt to use it, but it's certainly not nece$$ary for the average person. Suit yourself.
None of this tells you exactly what to use, does it? Nope, you need to evaluate that for your $elf.
- 'Doc
I would have to say that whatever coax you use just make sure that it will handle the power that you are running ...make sure it is in good shape,no breaks,cuts,sharp bends/kinks, and the ends are weather tight .....and I have always heard to use no more than needed to get to the antenna from your radio desk....I would add about 10 or so feet in case you move the antenna or radio desk
just my $.02
just my $.02
i agree with keeping it short as possible.but ya also want the best coax ya can
afford.like belden 9913 or lmr400.i believe antenna and coax are the most
important of any radio setup.
I will admit that in my 30 years of doing CB repairs, I have heard all the wildest crazy stories you could ever hear, and the coax debate is endless. Too many guys tend to over-think things and that's where they waste time and money, if you want to debate things, do so, but if you want to hook it up and talk, go buy some coax and talk.,but, I will also tell you, the answer is this simple and this short...
shorter is better and using the coax that is designed for your specific system is a grand idea, but, not a must.
shorter is better and using the coax that is designed for your specific system is a grand idea, but, not a must.
It's not as important as some make it out to be. Run low loss coax as much as you need and forget about it!
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@ ButtFuzz:Please advise me to what is a good replacement mic for my SR-497HPC... Answer: 497 is "wired like Cobra", so many choices available. That radio does not need a power mic, so purchase a stock "coffin style" mic with a decent cord, like the ones that Astatic uses. The Superstar DM-507 is my go-to. https://www.ebay.com/itm/3050474478...adANq91JSiEEnz8EGqPJRBloTgEyaVsBoCtoMQAvD_BwE $12.99 + .99 cent shipping.
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