I need more advice on installing an roof antenna to the coaxial cable through my home.

Question

This is a post from yesterday with additional details as discovered.

My cable got cut off due to lack of enough subscribers. I have an antenna on the roof that has not been used for years. I have a cable adapter from 300ohm to 75 ohm, but I am not sure what I'm doing. The antenna has two cables coming out the bottom that are about 1/4 in. each. They run the length of the attic and then go into the wall to what appears to be nowhere. Should I cut each of these wires, with each wire going to one of the s***w-on leads on the adapter? Any other information would be helpful. Thanks in advance for your input.

Additional Details

I got home from work and cut the two wires, and they turn out to both be coaxial, but they are smaller in diameter than other coaxial I have encountered. It is probably due to the age of the home/antenna. Any idea how I hook up two coaxial cables coming out of the roof antenna? I'm not sure what to do now. All I want to do right now is use the existing coax cable throughout the house with the old antenna on the roof. Other decisions will be made as needed. I need to get it all properly hooked up first.

Answer 1

Having two coax lines to a conventional antenna just doesn't make sense; either somebody did something unconventional before or you are mistaking what you are seeing.

For instance someone might have had a satellite dish on your roof before and ran the coax line through the same hole as the one for your antenna. They may even have had the dish (or a different antenna) mounted on the same pole.

You really need to get up and look at the antenna itself to see what is connected there. I DOUBT any cable that has been on there for many years is going to be any good to you at all.

You either need to use new twinlead (as suggested by Dusty above) or new coax right up to the antenna, only for the coax you need the 75-300 ohm transformer at the antenna end.

If you know EXACTLY where your coax goes in the house you might be able to salvage that end. You can couple the new wire from the antenna to the existing coax piece and perhaps make it work. I would still recommend new cable all the way to the TV though.

**update** I guess the thumbs down was from a lurker then. Oh well, can't please everyone.

More info: I just though of a scenario where there might be more than one coax from the antenna; If someone had a "distribition" amp on the antenna pole and ran several lines from it to different TV's then you might have the leftovers of that. I think you'll have to see what is up on the antenna though to check that part out.

Answer 2

Your best bet is to start at the antenna. If you can't reach it, you should be able to get to the wire or cable coming down the mast. It is not likely that the antenna will have 2 coax cables running from it, so I have no idea what you found in the attic. If it is old enough it will have 300 ohm flat lead coming down. You can splice that with the 300/75 ohm adapter at any location and run your cable from there. You will need an analog/digital converter if you want to use that after 17 Feb 09.

Answer 3

Smaller coaxial cables would indicate ham radio use.  TV uses RG-59 or RG-6 cable which is 75 ohm and a little fatter than the RG-58 used for two-way or ham radios is 50 ohm cable and won't work well for TV.  If you could post a picture of the antennas it would help.  There's no real way of knowing what you have otherwise.  

I'd recommend you simply start over.  Remove the existing antennas, put up a decent TV antenna, run new coax so you know you have the right stuff.  If you want to feed more than one room, get a TV signal splitter and run 2 coaxial cables.