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Wally38
Junior Member
Username: Wally38
Post Number: 49
Registered: 3-2005
| | Posted on Friday, November 18, 2005 - 3:43 pm: | 
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Does anyone use hardline coax for their CB setups? I've heard it has almost no loss.
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Chad
Advanced Member
Username: Chad
Post Number: 585
Registered: 11-2004
| | Posted on Friday, November 18, 2005 - 9:52 pm: |
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Hardline is copper pipe within copper pipe in coax form, it needs to be dehydrated with a desiccant pump or gas charged. It IS NOT flexible, Heliax is. I think a few are using Heliax but for the most part many see it as an utter waste of money. Heliax is still FAR from flexible, and still needs to be dehydrated.
Chad
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Tech833
Moderator
Username: Tech833
Post Number: 1097
Registered: 8-2002
| | Posted on Saturday, November 19, 2005 - 2:47 pm: |
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I am running 1/2 inch foam Heliax to all of my antennas. It works very well.
What would you like to know about it? |
Triplecguy
Intermediate Member
Username: Triplecguy
Post Number: 188
Registered: 12-2001
| | Posted on Thursday, December 15, 2005 - 6:50 pm: |
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I run inch and 5/8 heliax on my 2meter/440 ham rig up my 50ft tower to a 13db gain vertical antenna. I can be heard on 2 meters simplex over 200 miles away across the rocky mountains with 50 watts of power. However, they cannot talk back to me so what good does it do me? I have only N-connectors and use short pieces of RG-8 to adapt from the hardline to the antenna and to the radio since hardline is not very flexible. I have calculated my line loss between the radio and antenna between 1.2 and 1.3db, only because of the connectors, the hardline doesn't even have enough loss on 440 to matter even at the 125 length I use. Yes I have the loudest base set up on 2 meters and 440 around here but there IS a price to pay for it;
1. It is very hard to install and is very heavy. I used a crane to pull mine up the tower. It must be used on a tower or it will tear down your push up pole (my big stuff, not the 1/2" stuff)
2. It is horibly expensive vs. coax. My stuff goes for about 5-7 dollars a foot if I remember correctly.
3. Connectors are even more expensive. Depending on what connector you need at the ends of the hardline, they cost between 175.00 and 300.00 a piece!! Plus, you must have an installation tool kit to put them on as it is very difficult and time consuming.
4. Last but not least, don't forget that it is going to affect your receive as well as your transmit. I must run my dual band rig with the squelch attenuator in the full on position because most all ham FM transceivers have trash front ends that depend on a lot of loss in the coax to keep them quiet. I continuously, and I mean 24/7, have intermod and frontend failure where I have local police and fire over running everything I am trying to listen to. I even get a 146.790 local repeater that blares in over my 445.725 receiver. PL tones help a bit but a lot of the time data transmissions and such will open the front end right up. Although I have not used my hardline for anything less than 144.000 mhz, some of the problems I listed above may be something you need to take into consideration. You would probably have little or no problems with 1/2" or 7/8" harline, but the connectors are still very expensive and the stuff is still not near as flexible as regular coax. It was intended for the commercial market and is primarily used there for some of the previous reasons, mostly cost. But it will perform beyond what you could hope for. Without being a braggart, all of my heliax and connectors were given to me by a very nice gentlemen who worked for a paging company for free. There is no way I could have afforded to spend the money that it would have taken to get what I have. About 2 years go when I put the whole set up together, I went online and priced my stuff at over $1300.00. Who could afford to spend that on just coax and connectors? Maybe Bruce, but anyway, ask around with local CB'ers, hams and anybody else in the communications or electronics industry and I'm sure you could find some more opinions and some free stuff as well.
Good luck and let us all know what happens!!
Dan |
Tech833
Moderator
Username: Tech833
Post Number: 1128
Registered: 8-2002
| | Posted on Friday, December 16, 2005 - 10:27 am: |
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Tripleguy,
You CANNOT blame the poor front-end of your radio on your coax! When I first read your post, I couldn't figure out if you were joking or not, but as I re-read I can see you are not joking.
It is a well documented fact that poor coax will make intermod worse, not better. Your receiver is obviously a poor design or in poor health for your location and antenna gain. I have several Motorola radios here that get ZERO intermod from the other stuff on my tower (paging, two-way, broadcast, etc). I also have a Yaesu FT-90 that sits here ncie and quiet despite all the high power stuff just a few feet away. The Alinco goes nuts from the intermod jumping off the desk even with full squelch though. It has nothing to do with the coax. It has to do with poor front-end and a high gain antenna.
Also, since you mentioned you can 'talk' 200 miles but you cannot hear stations coming back to you from that distance, that is a CLEAR indicator that there is something wrong with your receiver! I would think anyone could see that. On VHF and especially UHF, stations with similar power will have a receiprocal path between them. If your radio cannot hear stations that can hear you, it is definately time to get that receiver fixed.
In order to avoid possible confusion to forum readers, I believe that clearly innacurate post should be deleted. Passing obviously incorrect information is what starts 'CB folklore' rumors. |
Wildrat
Intermediate Member
Username: Wildrat
Post Number: 499
Registered: 12-2003
| | Posted on Friday, December 16, 2005 - 1:17 pm: |
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Thats true 833,like having coax in coils, multiples of three, glass jars, lightning is uncontrolable, etc. etc
WildRat |
Therealporkchop
Advanced Member
Username: Therealporkchop
Post Number: 518
Registered: 11-2002
| | Posted on Friday, December 16, 2005 - 3:59 pm: |
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Why not just run Times LMR series coax? Like LMR400 or something?
It's clear that cost would cut out the hardline, atleast for me it would.
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Hollowpoint445
Advanced Member
Username: Hollowpoint445
Post Number: 960
Registered: 6-2004
| | Posted on Friday, December 16, 2005 - 5:06 pm: |
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Wow! Intermod from another band!?! I have a couple of scanners that have really poor resistance to intermod (Uniden), but they never have a problem with VHF while trying to receive UHF. That receiver is either VERY poorly designed or has been hacked so any bandpass filtering that existed was bypassed. |
Triplecguy
Intermediate Member
Username: Triplecguy
Post Number: 190
Registered: 12-2001
| | Posted on Friday, December 16, 2005 - 9:22 pm: |
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Mr. 833, excuse me for simply stating the facts at hand, I will try and rebute myself so as not to start (CB folklore rumors). I am running an Icom 2720 dual bander. Most everybody that has one agrees that the front end on them is poor at best. That is why they put the squelch attenuators on them, it is a cheap method to keep out unwanted signals. A Motorola or other quality commercial radio will not allow anything in that it isn't supposed to. This is a qulaity and PRICE issue. Second, the main Ham Radio manufacturers don't expect many of their customers to run a setup such as mine and therfore do not take the problems I have run into, into consideration. Most people that run regular coax that performs very well at 27mhz don't have any clue what attenuation does to their 144mhz or 440mhz signal. Granted, this post was about CB performance with hardline. I simply gave the results I have noticed with my dual band setup for the original posters information. I will, however, challenge you on the fact that the coax doesn't play a major role in fron end issues. If you remove the loss from a transmission line more signal is going to reach the receiver and then the receiver must decide what is allowed in and what isn't, and depending on the qulaity and ability of the reciever to stop unwanted signals, some may inadvertantly get in. I have almost a no loss system with a 17' antenna on top of a 10 foot mast on top of a 50 tower at 4692 feet above sea level. I had reports that a number of stations in a town approximately 200 miles away across the Rocky Mountains heard me, not well granted, but heard me. My reciever in my 2720 was not able to pick them up either because it is cheap and meant only for local communication or because of some other factor in the strange world of radio. Just because the frontend is flimsy, doens't mean it is broke. If I had the money I would of course purchase a high qulaity commercial rig, but I am unable to do so at this time. Rather than insult you and call you a liar or say that you are starting CB rumors, I would respectfully request that you reread my post and see that I am simply reporting my findings, yes they are open to interpretation, but I am here to learn where I can, and help the few places I can. I am an educated man, with more experience behind me than a lot of folks, and less than a lot of folks too. Please understand that I am not making up theory, but simply using it to help explain what may or may not be happening in my shack. You wrote that "It is a well documented fact that poor coax will make intermod worse, not better." That is an inverse statement to my situation. Excellent low loss transmission line will deliver more signal to your receiver from your antenna. Period.
Respectfully,
Dan |
Tech833
Moderator
Username: Tech833
Post Number: 1131
Registered: 8-2002
| | Posted on Saturday, December 17, 2005 - 10:34 am: |
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Dan,
No sweat! I have taken no offense, and I intend no offense to you. All I want to do is make sure that no inaccurate information is passed as fact here, and I want to squelch inaccurate information as quickly and permanently as possible.
You keep using the word 'intermod', but as I read your last post, it appears you are confusing intermod with 'overload'. Lossy coax WILL make intermod worse, but will make overload 'better'. If your receiver is overloaded, then giving it more signal will make it worse, that is true.
Intermod is the mixing of signals and site generated noise that produces more frequencies and spurs that would not have existed otherwise.
Again, overload is a problem for any receiver with inadequate filtering or a poorly designed AGC. You mentioned ham radios having low cost front-ends, that is usually true.
Now, again, how can you blame your high quality coax for your receiver overload problem? Back to basics for a minute, and for the benefit of other forum readers who are trying to learn about this subject, is it appropriate to blame anchovies for making my pizza taste fishy, or is it more appropriate to blame the pizza maker that put them on my pizza by mistake? Same thing here- If your receiver has a poorly filtered front end with a poorly designed AGC, and you use a high gain antenna in a high RF environment and high quality coax, then your receiver is getting overloaded.... Seems to me the coax is doing its job correctly. First thing to 'blame' is the poor radio receiver. If you insist on using that receiver, then choose a lower gain antenna. Here's why that makes more sense-
Coax loss works both ways. You not only lose watts from the transmitter to the antenna, you also lose microvolts from the antenna to the receiver. Using high quality coax and a low gain antenna will make your overload problem better. Using a high gain antenna and lossy coax will make your transmitter weak and your receiver weak, but not really 'cure' the overloading. Let me explain- You have to remember that in a high RF environment, RF will leak INTO the lossy coax and remove any benefit of a lower gain antenna. However, with lower loss coax (like your Heliax), the high RF fields will not be able to get into your coax, so any level of off-channel signal that is coming from the antenna can be easily calculated and controlled.
I hope this helps. |
Wildrat
Advanced Member
Username: Wildrat
Post Number: 506
Registered: 12-2003
| | Posted on Saturday, December 17, 2005 - 11:24 am: |
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OK,I got all that think I'll go take the General test now. *_*
Wildrat |
Triplecguy
Intermediate Member
Username: Triplecguy
Post Number: 191
Registered: 12-2001
| | Posted on Saturday, December 17, 2005 - 12:32 pm: |
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Very well written, and I may have used the wrong terms as I am not an expert. However, public safety in the 150 band and other stuff in the 450 and 460 band absolutley overpower my Icom. It sounds crappy when it happens, but it completely destroys everything else trying to come in. My antenna which is a clone of a Comet or Diamond (17 feet tall dual band) is very wide banded and allows the nearby signals to come on in with out any "resistance" so to speak. I also live less than 2 miles from a very powerful public saftey repeater that puts out 200 watts into folded dipoles and others have complained of my same symptoms, just not to the extent I have them. I could contorl them with a notch filter but then I couldn't monitor public safety and commercial servies, but there is a price for everything.
Dan |
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