Does antenna coax go bad?

[letterman]

I have an intermittent bad signal on the tv. I just took the antenna down and cleaned the screw connectors where the transformer adaptor goes. Then I replaced that transformer. I also checked the whole antenna nad it's all fine. Yet I still have a bad picture on analog, and digital dont work at all. I just cut off the plug on the antenna end of the coax and put on a new connector. I still got a terrible picture. All that's left is the coax. I get better picture on rabbit ears now and the antenna used to work great, and still does on occasion.

LM

[pheeh.zero]

[Ralph Mowery]

The coax can go bad. If it is bent in too tight a radius the center conductor can over time contact the shield as it cuts through the insulation. It can get water in it. The braid should be bright and shiney. It can also be mashed almost flat and the signal will not get through it very well. Television signals (RF) is not like direct current or the regular AC line power. Bends and flat spots can cause a suck out of signals.

[hibb]

I was wondering about that. I have a DVD recorder and it is hooked up to the Direct TV box. It has worked fine for several years and now I am not getting a signal to the DVD Recorder.

I have a separate cable to connect the Direct TV box to the TV and that still works fine and I can still watch DVD's on the TV.

David

[Nate Nagel]

I posted a while back about suddenly losing my cable. turned out it was a 3' run of coax between my surge suppressor and the cable box. No evident damage and it ohmed good, but the signal was marginal enough that the picture would pixellate and the audio would drop out intermittently. Made up another cable on the spot and haven't had a problem since.

nate

[Tony Hwang]

Hi, Unfortunately visual inspection is only good for physical imperfection.

[Jim Yanik]

"Ralph Mowery" wrote in news:GpKdnV1YMtaAzx_UnZ2dnUVZ [e-mail]:

Good post.

corrosion at the F-connectors is a major problem for coax. also loose connectors.

[makolber]

Yes coax can go "bad" especially if water gets INSIDE it.

Mark

[Malcolm Hoar]

Yes, the cable goes bad. More commonly, the connectors fail. But even with perfect connectors, the cable itself can be bad.

And failures can present in weird and wonderful ways. I once had a bad 3ft jumper cable (wall outlet to TV). It work perfectly, on most channels. But on a handful of other channels, the signal was totally shot.

Replaced that bit of cable and problem solved!

[pheeh.zero]

house. From there it goes to an indoor amplifier, and directly to either the tv, or the dtv converter (depending on which I am using). Just to be sure, I removed the amp and the short coax from the amp to the tv, and put the coax from the antenna directly to the tv. Still lousy picture, and weaker (no amp). There's only one thing left, the main coax. I just went and bought a premade 25 ft. RG6 coax, but I wont be going on the roof right now at midnight and at zero degrees. That's tomorrow's job.

You are amplifying a weak signal to begin with...loss with transformer and loss thru coax. You need an amp on the mast ($25). It's powered thru your coax. You can't amplify what you don't have!

[hallerb]

RG59 is very lossy in comparison to the far better RG6. Rg59 thinner, venter conductor copper plated steel, thin junk.......

put a new amp on the mast at the antenna after checking the website for what you need for digital tv.

your always better off with a better antenna than a amp that adds noise while amplifying signal

[Ralph Mowery]

You should not bend the coax very sharp. That can (especially in time) cause the inside wire to cut through the insulation and short out to the shield. I think the recommended bending is a radius of not less than 10 times the diameter of the cable. Also most of the coax is made with a coper coated steel wire that can break very easy if bent too tight or too many times.

For only about a 20 foot run there is not much differance in the rg6 and rg59. For longer lengths the smaller rg59 will loose more signal. Just use the rg6 and don't worry about it.

The coax can be taped to the mast. All the signal is inside the cable. Without getting into the technical part of things, the older twin lead type should not be close to anything that is conductive. There is a relationship to the diameter of the wire and the spacing that must be maintained. In coax this is met by the way it is made. When twinlead is used, the mast becomes part of the system if it is too close to the wire and some of the signal is lost.