Repairing Coaxial Cable - A Difficult Task? 13

[muthabored]

I'd been having trouble with my high speed internet (the connection would suddenly drop on its own for what appeared to be no reason). After speaking with my ISP's tech support, my attention was directed to the coaxial cable that comes in from the outside (the cable is frayed). They offered to send someone out to take a look at it/repair it but I'm wondering if this is something that I could do on my own. I have spare cable and I think I'd have to get one of those connectors (F81) and then something to cut/crimp the cable. Can anyone refer me to a website that might assist me with this? Thanks in advance!

 

[ArizonaGeek]

Well I gotta say I didn't realize coaxial cable was such a heated topic I mean forget Democrats and Republicans ... it's about coax.

Honestly though I am really fascinated by all this and learning quite a bit, I honestly just thought coax was coax was coax and never understood the actual inner workings of it. Now I've got something else to read about and get some more information. Stars all around for making me think!

Cheers
Rob

 

[gbaughma]

Therefore, the signal delivered by my cat5 cabling is actually delivered by the air around the wire, and not the wire itself?

No, because that is digital electrical pulses representing binary data, and not RF.



Just my 2¢

"What the captain doesn't realize is that we've secretly exchanged his dilithium crystals for new Folger's Crystals." -- My Sister
--Greg

http://parallel.tzo.com

 

[LawnBoy]

<grin> It's all about the coax, baby!

Like most scientific principles, the details are almost endless. Take magnets for instance, everybody thought we knew everything about them and then some joker comes up with superconductivity...

 

[LawnBoy]

Waitaminute, current is current. digital signals are square waves, analog signals are sine waves. The only real difference is the harmonic component.

What difference does it make what the signal "represents"?
Please explain your statement. Maybe you should define what you mean by RF; my LAN is operating in the RF range... (1 Ghz)

 

[Freestone]

If electrons are shooting down the copper and radio wave down the dielectric, then surely they would go out of synch as radio wave travel far slower than copper conducted electrons.

Stu,

You are correct that a slowing down occurs. This effect is known as Velocity Factor and varies by cable.

http://www.picwire.com/technical/paper2.html

http://en.wikipedia.org/wiki/Velocity_of_propagation

And that's what I've been saying! The Dielectric actually carries the signal,...

But that is not what I said. I stated that the dielectric contains the resulting electromagnetic field caused by the flow of current through the copper wire of the coax. It takes on the role of air in an open-conductor transmission cable. The diameter of the dielectric also has a factor in the characteristic impedance of the coax. I haven't even convinced myself the dielectric is totally responsible for the containment of the electromagnetic wave. I am sure that the outside shielding has a lot to do with this too.


I will say that the propagation of the signal is due to current flow in the copper wire, not the dielectric. We are in disagreement there, Greg.

 

[biglebowski]

From what I understand at lower frequencys the signal is carried in the centre of the condusctor core, as the frequency increases the signal gets closer to the outer surface. At high frequencys the signal is carried on the outside surface and some of this signal is lost due to radiation. The dialectric is there as both an insulator (air being the best that is why the best coaxs have a rigid outer screen and spacers rather than foam to increase the air volume) and to keep the braided shielding the same distance from the core all the way along the cable. The shielding is there to prevent any of the electromagnetic radiation escaping and also to prevent external fields affecting the signal quality.

Like I say from what I understand I may be wrong and I have been known to make up my own theories from time to time.

When I was born I was so suprised I didn't talk for 18 months

 

[wahnula]

I for one would like to thank everyone for helping educate myself and countless others with all this excellent information. I now see how a wave can move in the dielectric between the conductor & shield. Right or wrong, I have a picture in my head that satisfies me, where before there was just air...or foam.

Discussions like this are one of the reasons I like it here.

Tony

 

[LawnBoy]

No, because that is digital electrical pulses representing binary data, and not RF.

Since the original subject was a high speed digital circuit from a cable co, do you now retract your statement?

 

[gbaughma]

Since the original subject was a high speed digital circuit from a cable co, do you now retract your statement?

Ummmm... no.... why would I?

my attention was directed to the coaxial cable that comes in from the outside (the cable is frayed).

Meaning that he's got a cable modem, which uses unused analogue television frequencies. A cable modem is essentially a TV tuner and low-power transmitter which locks onto an unused ANALOG FREQUENCY and converts it to digital.

I'm really done with this thread now... I probably shouldn't have even responded to such a juvenile stab in my direction. I've done my best to give advice in this forum, and now you guys are just starting to be jerks. I've given information, backed it up with multiple sources, and I've been told that my sources (like encyclopedia britannica and wikipedia and howstuffworks.com) are unreliable???

If you guys don't want my input on the forum, please, just let me know; I'll be glad to remove it from my threadminder, and you can say goodbye to almost 30 years of computer experience. Because, frankly, I don't NEED this forum.


Just my 2¢

"What the captain doesn't realize is that we've secretly exchanged his dilithium crystals for new Folger's Crystals." -- My Sister
--Greg

http://parallel.tzo.com

 

[LawnBoy]

I probably shouldn't have even responded to such a juvenile stab in my direction

That was not my intention Greg. I didn't know that 'digital cable' actually comes in on an analog signal, I assumed it was a digital signal. My mistake.

 

[gitrdunn]

Ladies and gents, I think the original question got a bit lost in the smoke and flames. I found this post through Google b/c I wanted to fix my own cable for the same reason as muthbored. I don't know much about cable but I know that if you don't have HDTV (e.g., just your basic cable signal) and you need to repair a frayed cable, you can ABSOLUTELY do it yourself and you'd never know the picture quality difference (but you will in your wallet, which will be $40-80 heavier, and in terms of hassle, because this takes about 15 minutes whereas calling a "professional" will take days).

HOW TO DO IT:
You need: 1) A utility knife; 2) Needlenose pliers.

Find the damaged cable. Regardless of where the damage is, you need to ensure a quality line of cable from the neighborhood source box to your house and from the splitter (assuming you split the signal to multiple TVs) to the TVs. Usually animals will chew through the cable somewhere close to your house, so the instructions below assume this scenario (NOTE: If the damage is NOT at one of the ends of the connection, lay a new line rather than attempt to make a mid-way connection).

Remove the threaded connector from the now-cut away piece of cable (the part that connected to the house). With your utility knife, CAREFULLY cut away about somewhere between 1 and 3/4" of the rubber sleeve away from the new end of the good cable. Do not cut the metal braid. From the last 5/16" or so, cut away everything but the copper wire (this is so it can be plugged in to the receptacle). Carefully push the exposed portion of the good cable into the old connector, making sure that the thin-metal sleeve around the foam center is intact ALL THE WAY through (this is important b/c failure to do so will result in a terrible or nonexistent signal). When connected, the end of the copper wire should be about flush with the thread ring of the connector when looking at it in profile (it can extend a little father without causing a problem). Use electrician's tape to secure the connector to the cable (this serves to protect the connection from the elements and provides a reasonable level of solidity to the connection - admittedly not as good as if you used a crimping tool - which costs $40, but plenty good enough to last for years). Reconnect the new cable connection to the splitter (or whatever connector it was originally connected to). Test the TV. Wow, it worked. Close the housing box (where the splitter, etc. are). Go inside and watch TV. You probably want have to do this again until next time an animal chews through the cable (hopefully no time soon!).