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can i use cable from comcast to make a coax for my rigs and cb

R

rob

Member
Jun 21, 2011
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i got a crap load of cable from comcast and i took off the extra coax cable off my house and im just wondering if i can use the extra cable and turn it into a coax for my radio coax?? its the same coax for use for cb and ham rigs.. i got a crap load and just tryin 2 figure out if i can turn the cable into coax for my cb and rigs.. i got so much of it that i can do a 3 or 4 story house.. comcast are idiots and there just to lazy to remove the extra cable so i did it..i figure all i would need to do is cut the ends and put a antenna connector on either ends but im not sure and i dont wanna do something to mess my crap up.. the only difference is the cable is little bit stronger and bigger thats why im asking
 
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pappy.gif
Wow - is it really necessary to use Profanity (and Vulgarity) in your message? Anyway, take a look at: Can Cable TV coax be used for Amateur Radio applications?

Cable TV coax is, for the most part, RG-6, RG-59 and a few varieties of hardline. All of these cables have characteristic impedances of 75 Ω as opposed to the 50 Ω feed lines that hams use.

Does this mean that you cannot use Cable TV coax? Not at all. Assuming you have a modern-day rig, its output network is designed to accommodate a 50-Ω load, but the network can usually handle a 75 Ω impedance with little difficulty (you may see an SWR of approximately 1.5:1). Most dipole antennas, for example, have feed point impedances of 50 to 100 Ω, depending on a number of factors such as height above ground. So, a 75 Ω feed line should present a reasonably good match.

So why don’t hams use Cable TV coax? The answer is that some do, but there are several factors that make the traditional 50 Ω cables more attractive. Cable TV coax uses an aluminum shield and it is often difficult to solder. And as I’ve already mentioned, the 75 Ω impedance isn’t suitable for all amateur antennas. Having said all that, the price of Cable TV coax is often too low to refuse—as in free! Your local cable company often has “remnant” spools containing 100 feet or more of coax that they may be willing to sell at a nominal fee, or simply give away.

From QST August 1999
 
If you can deal with the impedance mismatch and soldering the aluminum, sure, why not? Is it a 'better deal' than 50 ohm coax? Money wise, yes. Effort wise, maybe not? If you got it, use it till you get tired of that 'effort' thingy.
- 'Doc
 
I am glad CJ decided not to bash KE3W's post as there is nothing wrong with it. The truth is that some hams do indeed use cable TV coax without a problem. In most cases it may require you to alter the length to achieve a proper match to the radio. Let's not get into a discussion about using a proper length of cable to tune an antenna as when using 75 ohm cable in a 50 ohm system is a special case where the length of the cable transforms the improper impedance to the proper 50 ohms. While RG-58 cable may well be cheap RG-6 is actually a better quality cable with lower loss and better shielding. I used 75 ohm 3/4 inch trunk line on a VHF system at one time and it worked perfectly so don't let ANYONE tell you that you cannot or should not use cable TV coax on CB or any other band. It may not be simple plug and play but it can certainly be made to work if you are willing to accept a slight mismatch or put a little knowledge and effort into the proper installation and matching. The problem today is that too many people simply want to walk into a store and walk out with everything to put a station together and no one seems to want to build antennas or experiment with anything any more. Too bad for them I guess. Go for it and use the cable, just make sure not to run too much power through it if you run an amp.You should be able to find connectors that fit the cable taking into account the aluminum shield and then use an adapter to get to a PL-259 connector.
 
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This one time,,,,,,at band camp,,,,,,,,,

Just kidding, but one time a friend and I came across a free MFJ dipole that was fed with 100 foot of 450ohm ladder line.

This friend lived on a 30 acre wooded lot. Using a cross bow we launched a string in to a tree that was well over 100 foot tall.

Once we had the apex tied off and the ends strung up, the 75 foot of lmr400 he had would not make it to the house :headbang

He just switched cable companies and the new company insisted on installing their own coax to the house. This left him with 130 foot of some yellow 75 ohm coax from the old company.

Being the RF connector junkie he was, he happen to have a bag full of F connectors to SO-239 adapters!

Attached the the connectors, attached the coax to the dipole, ran the coax in the house, attached it to a MFJ Manual Tuner and we were on the air.

This thing was so easy to tune. We made contacts from 160 meter to 10 meter all day and night.

We even hooked his LDG Auto Tuner (AT-897) just to try and it worked and tuned just as easily.

Now we were using a Yaesu FT-897D and only 100 watts.

We used this set up for over a year with no problems to the radio, sold the 897 and he bought a TS-2000 and it worked with the built in auto tuner.

Was this the ideal set up?????

WHO CARES! We were on the air talking!!!!
 
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Happy_Hamer said:
Was this the ideal set up?????

WHO CARES! We were on the air talking!!!!
Click to expand...

That's all that really matters in the end is it not? Number one priority is to get on the air. Improving what you start off with is priority number two. My first antenna broke a lot of rules but also worked a lot of DX. it was an 80m dipole fed with 450 ohm ladder line with the apex at about 35 feet. It was set up as an inverted VEE on a metal tower smack in the middle. The antenna was not offset from the tower with a dog leg or anything. The balanced feedline was run out from the basement and taped to a steel pole for about 7-8 feet and then run over to the tower about 20 feet away. From there it was taped to the steel tower leg breaking all the rules regarding the running of a balanced line for the rest of the way to the antenna. The antenna ends were about two feet off the ground. I worked a lot of DX with that setup using some CW and AM,no SSB, from a Heath DX-60B and separate receiver. I would zero beat a station I copied on SSB and then use my massive 50 watts of carrier controlled AM to call him. Most times they had no idea I was on AM. I worked many stations into Africa,Europe, and even Barnaul in south-central Siberia using that method. What I am trying to say I guess is that rules can be broken and you can still have great results.If you have the right knowledge then it is more like bending the rules rather than breaking them. Experimenting is what it's all about and learning what works and what does not. No matter what you have someone will say to get something better but as long as YOU are satisfied with the performance then all others can go pound sand. :D
 
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Channel Jumper said:
Im not going to bash KE3W's post.
What I am going to tell you is that the first radios made were all 50 ohms and so to keep it so one antenna set up would work on all radios.
Click to expand...

Not quite right. Radios have been around a lot longer than coax. The first radios had outputs for single wires, and the operators were expected to know that they would have to provide the counterpoise/radial system for this type of antenna. Different outputs made it possible to feed a balanced antenna with tuned feeders, otherwise known as parallel line, open-wire line and which evolved into 300-ohm twinlead for television - again, well before coaxial cable was commonly available.

After the end of WWII, the military released miles and miles - literally - of what was called "RG-8/U" cable which had been developed as HF feedlines into the surplus market. It happened to have a characteristic impedance of 50-52 ohms and was pretty consistent in its other electrical properties.

It wasn't until THEN that radio manufacturers began standardizing their outputs at 50 ohms - to match the most commonly-used coaxial cables. Not long later, TV manufacturers realized that shielded coax was a handy alternative to the flat 300-ohm stuff then in use. Using a balun to transform the 300-ohm impedance to 50 ohms would have required a 6:1 impedance ratio: tricky to design, and not cheap. They found that a 4:1 ratio was a lot simpler and cheaper - so they designed a 75 ohm coax. Called it RG-59 and the rest is history.
 
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ok i do wanna say this YES im a noobe in this ham radio thing but what ive been learning about hams that its sometimes you need to experiment and thats what i been learning and i love it more and more.. im different and i love it and i think outta the box, yes going to the store and buying store but coax is the easiest BUT what are you learning if you just be safe.. some people did listen to my question and i thank you for that.. i do know a lot about electronics and dealing with comcast for over 10 years i learned a lot because they dont seem to fix my signal and yes i know about dbs and shit like that.. i know ham radios are different and yes i wanna learn all that good shit.. the main reason that i asked this question was i got so much cable i been trying to figure out what to do with it all.. im not rich nor got money coming outta my ass im poor as hell and what im saving my money for a yaesu ft 897d and thats goin to be about a grand, so that being said im not trying to brake it.. yes i want to learn hella a lot more about ham radio and im learning a lot to.. BUT for real tho isnt ham radio about learning and experimenting as long as you do your research of what your trying to do.. well thats what im getting after watching videos and reading online.. or is it just me being old school??? o ya i am going to radio shack and buying few things and yes im going to try it
 
rob said:
ok i do wanna say this YES im a noobe in this ham radio thing but what ive been learning about hams that its sometimes you need to experiment and thats what i been learning and i love it more and more.. im different and i love it and i think outta the box, yes going to the store and buying store but coax is the easiest BUT what are you learning if you just be safe.. some people did listen to my question and i thank you for that.. i do know a lot about electronics and dealing with comcast for over 10 years i learned a lot because they dont seem to fix my signal and yes i know about dbs and shit like that.. i know ham radios are different and yes i wanna learn all that good shit.. the main reason that i asked this question was i got so much cable i been trying to figure out what to do with it all.. im not rich nor got money coming outta my ass im poor as hell and what im saving my money for a yaesu ft 897d and thats goin to be about a grand, so that being said im not trying to brake it.. yes i want to learn hella a lot more about ham radio and im learning a lot to.. BUT for real tho isnt ham radio about learning and experimenting as long as you do your research of what your trying to do.. well thats what im getting after watching videos and reading online.. or is it just me being old school??? o ya i am going to radio shack and buying few things and yes im going to try it
Click to expand...

I am noob to this kinda thing too. However, you are gonna find when you ask a question or post a comment you may get flamed. Take it with a grain of salt ( so it tastes better) learn from the flame what you can and move on.

Now do what ya gotta post some pics and tell us what ya learned please!!! ;)
 
all i was is stated a facts and you know what screw the people who try to get me flamed but hey i just got home and what i got is solder type PL 259 UHF type connectors so well see how good it works soon... but hey thats why i want to get to know more about hams and hey least im experimenting see what works and doesnt for me and you know what least i can say that i tryed
 

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