ECN Forum Forums General Topics of the Trade General Discussion Area VDV questions for Bill

Hal,
Some of the homes I wire for this company only have damage to 1 or 2 rooms. The walls are already full of RG59 (the small stuff). When I replace the coax in the damaged rooms are you saying I should not or cannot splice into the old system? What would happen if I did? The only alternative I have is to make new home runs and staple them to the outside of the house where the walls are unopened, since many homes here have neither attics or crawl spaces. (I am assuming it is RG59 as a normal connector does not fit, only an F connector will work.)
Thanks, Brian

You can splice RG-6 to RG-59. They both take F Connectors (the standard CATV screw on we all know), the only differnece is that you have to get the connector for the type of cable you are using. A RG6 connector will have a larger barrel in the back, but the part that screws into your TV is the same as that on a 59 connector, or even an RG-11 connector. in your case, just crimp the appropiate connector on your old and new line, and use a coupler to join the 2. Not the ideal way to go about coax, but I think if you have no other options, it will get the picture on the tv!

Does anybody know if there ae any tech issues like mismatched impedance or similiar when you splice RG-6 to RG-59?

Splicing isn't a great thing for video, but probably better than running wire down the outside of the house.

Anytime you splice a signal cable, there's change in the impedance of the cable at the splice point, which results in a reflection. The better the splice is, and the closer the cables are matched, the less of a "blip", and the less the problem. Best case would be 2 cables of the same model number from the same manufacturer.

With random RG-59 and random RG-6, I'd guess you'd lose about 1.5db. (That's a guess, I'm used to working with radio stuff, not cable TV) So anyway, the loss of the mis-match should be quite a bit less than the loss from a splitter. More important is that you'll be cutting the signal strength to the devices that cable feeds by slightly more than 1/2 because of the splitter.

What's critical, though, is to figure out which side of the wire the signal is coming from, so you can put in the splitter correctly. It might work backwards, but it'd be lousy compared to the right way.

You'll be changing the balance of what could be a well designed TV distribution system. Often the cable TV setups are lousy anyway, and the cable company just pushes the signal up enough to compensate for the loss.

At least one exception to all of this is if they're running a cable modem for Internet. Those require such a good signal that adding a single splice or splitter can sometimes break them. The line to watch is the one running from the pole to the cable modem - don't splice that one. Anything that's already split off of that can be split without interference. Digital cable may be the same thing, I don't know. If so, it would be the same concern - the line from the pole to the digital cable box(s).

Use a good quality splitter. There used to be some really cheap ones out there, don't know if there still are.

"While I'm ranting about CAT5....."

I'm glad it's not just me. Every once in a while I see both CAT3 and CAT5 correctly used for a drop, and it always gives me a warm fuzzy feeling.