Coax wiring for reliability

[Sam Lord]

Hi folks, having many reliability problems with cable modem service, and I'm pretty sure it's a coax wiring problem. I've spent *weeks* on this infernal mess and eliminated everything but the internal house coax. We *must* have reliable broadband, my wife is in an online accelerated Master's program. Digital TV cable working fine, no dropouts on HD channels, etc., but internet cuts out, even tried switching TV and cable lines and eliminating cable box. Literally everything else including outdoor cable to company's distro box has been replaced with same results; great speed tests when connection works, electricals look great on the Cable tech's measuring gear, then modem disconnects hours later at no particular time of day. Not a cooling or power delivery issue. THREE modems now... two Mot SB 6120 and a Mot 6141, all exhibiting similar behavior. Router and other coax wires replaced, similar behavior. We use one cable modem at a time (duh) and one router (Linksys WRT54GL) at a time--router tests and behavior always nominal. We are about to replace the RG6 cable, so I'm looking for suggestions on:

 

1) Connectors: does anybody bother to use (75-Ohm characteristic Z version) BNCs or other high-quality connector types on their wall outlets? I think F connectors are the spawn of Satan, sorry for the profanity. If there is a BNC kit that crimps easily to the Coax, I'll use it. Don't want to solder, very hard for my disabled body to bend low for that delicate work.

 

2) Wire: Anybody use over-specced wire? I have a very conscientious electrician who uses radius-protectors for coax where it is stapled to walls, but I don't want to mess with my bloody coax ever again.

 

3) Anybody use a powered coax distribution splitter? I have a single passive splitter in the system, thinking of insertion losses.

 

All thoughts welcome, thank you.

[Sam Lord]

OK, after an insane amount of work, a good 40 hours of proper operation has happened. Cable techs and I found that:

 

1) Either the somewhat weather-corroded tap from the outdoor cable distro connection (cable company property) next to my house or on a neighbor's distro caused the intermittent outages; or 2) it was internal wire, the last old wire section that was changed out. We'll never know. I wish I could have installed the wire and tested everything, but my wheelchair nixes that.

 

3) The installers used plastic cable anchors and nicely radiused curves in the replaced line, so I'm happy.

 

3) I'll keep the passive splitter, it was changed out also.

 

Now I'm finally ready for hard-wired ethernet connections, AppleTVs for vid and secondary zone distribution, and Audirvana 1.4.6 Integer mode and 24/96 file conversion done and filed in memory for all my FLAC files (why not?). Then DSD...

 

Cheers

[jcn3]

sounds like you've made progress. getting rid of bad/rusty/leaky connectors could have been the source of the problem.

 

here are my recommendations for coax:

 

* always use rg6 quad shield in your house -- the high bandwidth requirements make quad shield important. for long runs to the house or from a satellite dish, you may need something even better

* never use the crimp-on fitting -- always use compression fittings. for outside use, you should use watertight compression fittings.

* try and only have one splitter for the whole house and use the size you need, avoiding having unused ports -- splitters are not good for the signal.

* related to above: only connect what you need. if you don't need it, don't connect it.

 

good to see your network is using wired connections wherever possible -- wired is always better.

[Sam Lord]

jcn3, Thank you for this advice; I've followed it pretty well I think:

 

I tried to see what type of RG6 (it was definitely RG6) the company used, but couldn't reach the area. Wish I could have specified Belden 1694A but oh well. I spoke at length with the senior tech, who did most of the work himself and who, I'm happy to say, was a stickler for good mechanical installation and really understood and practiced good strain relief, for example shunning metal cable anchors (preferring plastic ones) because of their tendency to distort and sometimes bite coax. They did use compression fittings at every connection, and good strain relief with many well-placed anchors. I now have exactly one coax splitter in the system inside, and there will be no others. Outdoors there is a single watertight (with seals) coupler: it was previously a splitter with one cable (to a back-room coax outlet) disconnected, but that wasn't the problem source. The tap on the telephone poles was replaced. I am using the absolute minimum number of connectors on both coax and ethernet cables to avoid insertion loss and reduce mechanical risks--IME around 95% of electronic problems are mechanical in origin. System has been perfectly reliable 4 days now, looking good for the next stage of installation.

 

Thanks again, Sam

 

sounds like you've made progress. getting rid of bad/rusty/leaky connectors could have been the source of the problem.

 

here are my recommendations for coax:

 

* always use rg6 quad shield in your house -- the high bandwidth requirements make quad shield important. for long runs to the house or from a satellite dish, you may need something even better

* never use the crimp-on fitting -- always use compression fittings. for outside use, you should use watertight compression fittings.

* try and only have one splitter for the whole house and use the size you need, avoiding having unused ports -- splitters are not good for the signal.

* related to above: only connect what you need. if you don't need it, don't connect it.

 

good to see your network is using wired connections wherever possible -- wired is always better.