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Bman02
| | Posted on Wednesday, September 18, 2002 - 7:47 pm: | 
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Right now im using belden rg8x(the thin stuff) coax on my base on an antron 99.Im probably gonna go down to the local rip off cb shop and get some rg8 this weekend.Do you guys think ill notice a difference or not?Also is rg213 better than rg8 or about the same? |
Taz
| | Posted on Wednesday, September 18, 2002 - 9:57 pm: |
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213 is much better.
Coax plays a very important role in performance.
How long of a run are we talking about here? |
Karatebutcher
| | Posted on Wednesday, September 18, 2002 - 10:07 pm: |
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Bman02 rg8u I have been useing this type of coax for years, I use 50 feet of it and have good results,and good swr. others say the rg213 is real good also, you will have to do your homework, and listen to the reports that come in on the forum, there is a mention in the forum on coax, you will have to search for it I don't exactly know where it is. |
Marconi
| | Posted on Wednesday, September 18, 2002 - 10:21 pm: |
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If the mini8 is in good shape, you will not notice much if any difference between RG8, RG8X, and RG213. The better shielded stuff is best of course.
I ran a 100 feet of mini8 for about 10 years and it got contaminated. I placed a meter at both ends of the line and check it with a dummy load. With the meter at the radio the line showed normal output, about 5 watts. With the meter at the dummy load end, I was only seeing a 1/4 watt.
Just check your lines for thruput. At a 100 ft or less, there should be no differences noted.
Belden make very good coax.
Marconi |
DeadlyEyes
| | Posted on Wednesday, September 18, 2002 - 10:38 pm: |
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OK lets do some research and some math.
Mini 8 coax is perfectly good coax for the CB Service as well as the Amateur service using barefoot 100 watts on HF.
So lets look up the charts and do some math. Go to the cable charts of the coax merchant web sites and look up the loss per 100 feet of the mini 8 and the coax you are seeking to buy. Figure out how long of a run you will need and determine the DB loss you will probably experience.
IF by using the larger, more expensive, coax you save one Db of loss. Given the cost of the the more efficient coax is it that critical to save that amount of DB? Do not be too emotional. In the practical world will the other guy ever know you spent the big bucks? Will your signal reception be that much better compared to the cost you will have to pay? These are questions that only you can answer.
Get out the old legal pad and write down the numbers, costs, benefits, etc. Study the big picture. |
Moderator558
| | Posted on Wednesday, September 18, 2002 - 11:04 pm: |
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RG58 @ 100 foot
Frequency (MHz) 27.385
Attenuation (db/100 feet) 2.357
Average Power (kW) 0.57 (approx. 570 watts)
Total Run Attenuation(dB) 2.4
Efficiency 58.1%
--------------------------------------------------
LMR 400 ULTRA FLEX @ 100 foot
Frequency (MHz) 27.385
Attenuation (db/100 feet) 0.784
Average Power (kW) 2.88 (approx. 2880 watts)
Total Run Attenuation(dB) 0.8
Efficiency 83.5%
--------------------------------------------------
RG213 @ 100 foot
Frequency (MHz) 27.385
Attenuation (db/100 feet) 1.034
Average Power (kW) 1.97 (approx. 1970 watts)
Total Run Attenuation(dB) 1.0
Efficiency 78.8%
http://www.timesmicrowave.com/cgi-bin/calculate
hope this helps |
Bman02
| | Posted on Wednesday, September 18, 2002 - 10:49 pm: |
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Yeah i run about 75 feet. I used to use rg8 and it worked good for me but ive read a lot of good reports on the 213 so i might try it.Decisions decisions. |
Taz
| | Posted on Wednesday, September 18, 2002 - 11:08 pm: |
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why not try it? Its better than rg8 by far |
Bman02
| | Posted on Wednesday, September 18, 2002 - 11:27 pm: |
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The stuff i got now isnt rg58-its rg8x (the slightly larger grey stuff).I just wandered if i would notice a difference if i bought the larger more expensive stuff.When you say 1 db is that basicly like 1 s-unit??Seems to be a lot of mixed opinions. |
Taz
| | Posted on Thursday, September 19, 2002 - 12:03 am: |
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The bigger coax handles more power, less signal loss on receive and transmit.
A few more bucks for much better coax.
Its still better than rg8x.
I would take the 213 |
828
| | Posted on Thursday, September 19, 2002 - 12:15 am: |
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6dB = 1 s unit |
bruce
| | Posted on Thursday, September 19, 2002 - 4:54 am: |
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At 27 meg lmr-400 is as good as you will ever need. We use it for all our jail repeaters ( 460 mhz ) never had a problem with it and some if it has been up there pushing 10 years. Stay away from OLD coax it's a "toss of the dice " as to what you will get.
Bruce |
Marconi
| | Posted on Thursday, September 19, 2002 - 8:30 am: |
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828, is probably right in his comment. 558's post does not include the qualities of the RG8/x line that you are using however. You will get some improvement with a better line, but no body will probably notice.
Most folks that are using 213, do so because of the wattage it is able to handle. LMR 400 probably has the best all-a-round qualities as 558 notes and also has this same quality regarding the high power thing. Most have a pretty good feeling that what they run is best. That will probably work on your mind too. So, I suggest that if you get a sense that something will work best for you, then go for it. Otherwise you will begin to question your decision and start second-guessing. That often produces bad feelings.
Do you think you are having some kind of problem with the RG/8x setup? Is the coax old or of cheap quality? Staying with the big brand name products is usually a good idea. I doubt you will find such at your local rip-off shop as you note.
Before you go up with the new line, check both like I suggested above and let me know how that turned out for you. Let us know what you decide and how it worked out in your case.
Marconi |
Bman02
| | Posted on Thursday, September 19, 2002 - 7:40 pm: |
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Theres no problem with the coax i have now and it really isnt that old.like everybody else im always trying to improve.Thanks for all the feedback. |
Tech671
| | Posted on Thursday, September 19, 2002 - 11:23 pm: |
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LMR400 or Davis Bury-Flex is very close to the cost of 213. You will notice an improvement in tx and rx with runs over 50'. |
Sarge
| | Posted on Thursday, September 26, 2002 - 5:28 pm: |
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One minor note on coax. The military specification on "RG-8" coax does not exist anymore. It was replaced a long time ago by the milspec standards for RG-213. That's why nobody in the military uses "RG-8" coax. It's always RG-213, or in rare cases RG-214.
The net result is a lot of companies making "RG-8" coaxial cable of poor quality. Since there is no longer a milspec for it, they can pretty much make it however they feel like. There is no published standard to hold them to. I have even seen coaxial cable marked "RG-8 Type", which makes me wonder how far off from the original specifications it might be, since they are not even trying to claim it is RG-8 cable.
RG-213 coaxial cable manufactured by Belden is always a good choice. The LMR 400 cable is also well established in the Land Mobile Radio (LMR) industry. |
Bigbob
| | Posted on Thursday, September 26, 2002 - 6:29 pm: |
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About 7 years ago I bought 75 feet of Radio Shack rg-8 coax,at that time it was the new version.The dieletric is solid white poly-ethylene and the jacket is non-contaminating vinyl,very stiff stuff,type cl-2.I had a piece of rg-213 and tried to solder it with a propane torch and the dielectric turned to liquid before I could finish;torch had medium flame.I did the same with the rg-8 and an outer layer of the dielectric liquified but the core around the center wire stayed firm and I was able to finish soldering.The only thing I've seen that's tuffer is Teflon.Does R.S. still make this coax,I took mine down last year and tested it with a dummy load 1to1 swr 4watts in 3.7 out 75ft.not bad. |
scrapiron63
| | Posted on Thursday, September 26, 2002 - 7:22 pm: |
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Your right about the great differences in different brands of RG-8U, however there is some RG-8U better than RG-213. I live about 2 miles from a Belden Cable Plant, and a few years ago I needed a roll of coax, a friend was a foreman at the plant, and could get it for me at a good price, I was going for 213, but he advised me to get 8214 RG-8U, said it was just a little more money but better coax, so I followed his advise, and it is the best I have run. Belden makes 4 different RG-8U coaxial cables that are better than their 213 if you look at size of center conductor, #11 compared to #13 for the 213, shield 97% compared to 96% for 213, and all other specs are better. Below is the link to their site, just type in the number, then read all the specs.
8267 for RG-213
8214, 9354, 9355, 9356 are the 4 types of RG-8U, they are all about equal.
http://bwccat.belden.com/cgi-bin/ncommerce3/ExecMacro/BELDEN/frames.d2w/report
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Marconi
| | Posted on Thursday, September 26, 2002 - 8:07 pm: |
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You are right Scrapiron, I check every piece of coax I get for thruput. If it does not show good, it goes back.
I also test a 1/4 wave piece or cut a 1/2 wave section to confirm the VF using a noise bridge. That comes in very handy and I find it is pretty reliable.
Marconi |
Bigbob
| | Posted on Thursday, September 26, 2002 - 8:36 pm: |
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Ever get the feeling you're talking to yourself,anyone. |
Marconi
| | Posted on Thursday, September 26, 2002 - 9:25 pm: |
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Hey Bigbob, I will talk to you. Did you check the SWR and output with the meter comparing at both ends of the line?
Consider a line that is electrically sound, but is found to be contaminated with age and weather. Assume it will pass a continuity test but only lets .25 watts thru to the end, with 5 watts input. This line will likely give you a good SWR report as well. You are in fact only checking the load in this case and SWR will not cut it in testing this way.
The proof in the pudding will be noting a reduction, if any, in RF getting to the meter at the other end of the line. To a degree this will also depend on the length being around a 100 feet or less. I do not know what you did in your case, using 75 feet, but I would not have been satisfied if only 3.7 watts was all that got to the end of the line.
How say you?
Marconi |
Alsworld
| | Posted on Thursday, September 26, 2002 - 9:42 pm: |
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Bigbob, I'm with you man. Probably why I'm on the radio and on the internet because the wife sure don't listen to me anymore! (okay, I'm just kidding about the wife) but yes Bigbob, talking to myself at least keeps me company. Just maybe with the "DX-a-thon" this Saturday (yes I hate the name but couldn't think of anything else to call it), you can join us and we can talk to ourselves together.....er....that didn't sound right huh? Hey I never claimed to be sane.
Welcome to Alsworld, where the key to sanity is to stay insane. |
HoosierCardinal
| | Posted on Friday, September 27, 2002 - 5:45 pm: |
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Ive never heard of LMR 400 until i got on the net. i use mostly 9913 here. |
Bigbob
| | Posted on Friday, September 27, 2002 - 6:09 pm: |
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I had a swr meter at both ends,4 in and 3.7 out is very bad,Hmmmmm.The watt meter on the far end was an old one I had sitten around,the other was my digital,maybe the old one is miss calibrated,the screws on it are all buggered up. |
Karatebutcher
| | Posted on Friday, September 27, 2002 - 6:16 pm: |
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Alsworld Now here is one man who really needs that meter,{for Talk Back} I get all my talk back from my wife. |
Karatebutcher
| | Posted on Friday, September 27, 2002 - 6:16 pm: |
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Alsworld Now here is one man who really needs that meter,{for Talk Back} I get all my talk back from my wife. |
Marconi
| | Posted on Friday, September 27, 2002 - 7:07 pm: |
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Bigbob, that is a good procedure. Now do it again and then reverse the meters to see if they are giving the same results. That will tell you if they are reading the same or not.
If that does not work out too well then use your best meter and move it from one end to the other. Of course it would be better to have two meters that read the same, but you have to do what you have to do.
I did not say 3.7 was VERY bad. I said it would not be acceptable to me and I would return it. Another thing I do, is feel every inch of my line to see if there might be a patch in there somewhere. You can tell if it does, then take it back if you can't cut it at this point and still use it like you planned.
Marconi |
Znut
| | Posted on Friday, September 27, 2002 - 7:56 pm: |
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Hey Bigbob,
Swap the meters around and see if still the same. If you have more power with the meter on the other end leave it there. It's like having an amp. |
Alsworld
| | Posted on Friday, September 27, 2002 - 8:08 pm: |
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Uh oh, that Karatebutcher is trying to spend my money. Man I sure do like the looks of that meter too so I guess you'll probably be successful.
Alsworld |
fdirsh
| | Posted on Thursday, October 03, 2002 - 4:34 pm: |
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where can I buy some lmr 400? |
Alsworld
| | Posted on Thursday, October 03, 2002 - 10:01 pm: |
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fdirsh,
if you don't get answers, e-mail me and I will give you some help.
Alsworld |
Tech833
| | Posted on Friday, October 04, 2002 - 12:49 am: |
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Copper has been planning on carrying LMR-400 cable. Call the 800 number and see if it is in stock yet.
LMR-400 is a good choice for installations that do not include a rotor. |
Taz
| | Posted on Friday, October 04, 2002 - 2:20 am: |
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why is it good for not rotor?
What is good for a rotor? |
bullet151
| | Posted on Friday, October 04, 2002 - 2:46 am: |
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tech833,
glad you brought that up.
alot of guys just use a jumper at the top of the tower thats flexable like the lmr400 ultra flex or 9913f,for beam work.
that is a good point to make though, that stiff coax with "solid" centers will break after to many bendings.
i tend to be a over builder/overdoer but ive got a roll of lmr600 and plan to use a short jumper at the top for my six element quad. coarse its still on the floor of the radio room.haha it presently has mini8 coax on it. i do have 100ft of 9913f going to my 27mhz colliner array.was using 9913 but it became waterlogged.  ya should have used coax sealant but i was in a hurry
to play and didnt take the extra time......we've all been there before im sure.  |
Tech833
| | Posted on Friday, October 04, 2002 - 11:50 am: |
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Taz,
LMR-400 has a solid center conductor which, when bent back and forth enough times, will fracture. Also, the foil shield will become loose and could fail as well.
For installations like a vertical which does not move, LMR is a solid choice. The jumper idea for installations requiring movement is also a good idea.
On the one antenna I have that moves, I use Andrew 7/8" Heliax all the way to the rotor, then a short flexible jumper to the antenna. |
Znut
| | Posted on Friday, October 04, 2002 - 1:14 pm: |
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Fdirsh,
Is the email address under your profile correct? I emailed you with some info.
Email me.
Znut
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Buck
| | Posted on Friday, October 04, 2002 - 5:28 pm: |
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I ve got about 75' to get to my Imax 2000....I dont want to(wife says I cant)spend much money....Will mini 8 work good for this run. Im currently using 8/u but it is at least 15yrs old and I want to replace it |
Taz
| | Posted on Friday, October 04, 2002 - 6:35 pm: |
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cool 833, thanks for answering my question.
Are you saying that coax that is stiffer is better for rotors? |
Taz
| | Posted on Friday, October 04, 2002 - 6:35 pm: |
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cool 833, thanks for answering my question.
Are you saying that coax that is stiffer is better for rotors? |
Taz
| | Posted on Friday, October 04, 2002 - 8:34 pm: |
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hmm, um echooo echooo echoo |
HoosierCardinal
| | Posted on Friday, October 04, 2002 - 9:56 pm: |
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Taz..
LOL!! Same thing happened to me a few times... |
Capdude
| | Posted on Friday, October 04, 2002 - 11:35 pm: |
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Why use rg8 simple $ rg213 big $ rg8 less $ |
bruce
| | Posted on Saturday, October 05, 2002 - 7:17 pm: |
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Buck 15 YEARS OLD? i have a rule i dont use old coax or buy cars from honest abes! ill bet the rg-8x has less loss that what your running |
bullet/151 southern Indiana
| | Posted on Saturday, October 05, 2002 - 11:23 pm: |
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taz,
no just the oposite, use the stiff stuff for non moving antenas unless you use a flexable jumper at the top. |
Taz
| | Posted on Saturday, October 05, 2002 - 11:48 pm: |
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ok i see, so hardline wouldnt be good to run directly to a big antenna? |
Tech833
| | Posted on Sunday, October 06, 2002 - 12:16 pm: |
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Hardline is non-flexible (like water pipe) and is not really going to gain any performance over Heliax or similar cable for your CB installation. Hardline is used mostly for AM and SW installations where high power handling is required and it is either directly buried or run inside some means of support which does not allow it to move. Hardline is sold in 10 or 20 foot sections and is extended with the use of bullets for the center conductor and either solder sleeves or bolted sleeves for the shield.
On the other hand, Heliax comes on a spool and is semi flexible. Heliax can be direct buried, suspended overhead, and all sorts of other schemes since small amounts of movement will not harm it.
For minimum loss, running Heliax from your radio to the antenna is certainly best. In the case of a directional antenna with a rotor, Heliax should only be run to the rotor plate, then a short flexible jumper (like 9913, 9914, etc.) is run from the Heliax to the antenna itself. This allows for movement of flexible cable when the rotor turns, but does not stress the Heliax with the movement. |
Bigbob
| | Posted on Monday, October 07, 2002 - 8:40 pm: |
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DUH,I'm gettin a headache. |
Taz
| | Posted on Tuesday, October 08, 2002 - 12:11 am: |
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Ok bigbob, give me an 11 digit prime number. |
bruce
| | Posted on Tuesday, October 08, 2002 - 7:48 am: |
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Taz was it the same one he gave me
1-900-hot-coax ...... or was that babe? |
Znut
| | Posted on Tuesday, October 08, 2002 - 3:21 pm: |
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Aren't equivalent sized heliax and LMR type cables nearly the same at 27 mhz other than the ruggedness and cost? At 6 gigahertz the Andrews Heliax is definitely better. I know the heliax can handle some hefty power too, but it's pretty expensive. I've installed a few connectors on that stuff, only "N" types and "7/16" types so far. I have put conn's on many LMR assemblies up too LMR 900. I wish I could get a run of that to my dual band omni. You don't get much of a signal out of the other end of RG 58 at 440 mhz,
Znut |
bruce
| | Posted on Tuesday, October 08, 2002 - 6:35 pm: |
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znut lmr for cb if it was me would be the best i would ever buy of course when your running 4 watts not much matters but losses on 27 are small even for rg-8 |
Znut
| | Posted on Tuesday, October 08, 2002 - 11:24 pm: |
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That's right,
However, you know that in your system, your coax and your antenna efficiency also make a difference on receive. I'm telling you, mini 8, RG8 or RG213 are fine when you are dealing with 100 feet or less (RG8/RG213 are good for even longer stretches). RG8 and RG213 are tough and still affordable.
If you have to deal with longer runs of cable, high power, or higher frequencies you must think about lower loss coax. By higher frequencies I mean VHF or UHF. The CB band is HF, under 50 Mhz.
I would definitely run LMR 400, 9913 or 9914 if I could afford it. I would make double sure to weatherproof the connections and make sure NOT to kink it (I guess this applies to any coax, but foam core cable is more fragile).
That said, I would rather buy very capable coax and have enough $$ left over to buy a decent SWR meter or mic.
Znut |
Buck
| | Posted on Thursday, October 10, 2002 - 10:45 pm: |
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Has anyone ever used the double shielded mini-8 coax? Its 95% copper shielded and also foil shielded, I was just wondering if it was decent stuff.
Thanks |
Tech671
| | Posted on Friday, October 11, 2002 - 9:15 pm: |
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Yes, Times LMR240 and CQ Mini 8 lo-loss. Both rated to 1kw RMS. |
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