Long run of RG-59

[KD0OTK]

Hey guys. Kind of in a jam here. I get bad simulcast distortion from my local tower. I would like to put a yagi in the attic, but the only cable that runs to the basement is RG-59 for cable TV. I'm guessing there is about 50-100 ft of it. I've tested the antenna in the upstairs and it works great. Would the loss from the coax make it not even worth it? Forgot to mention above that this would be for a scanner.

 

[n5ims]

RG-59 is OK, but it would be better if you could use RG-6 (that's just a bit larger, but lower loss and better shielding). Since you have the antenna and coax already ran, try it and see how it will work for you. The cost is probably only a couple of adapters and you'll find out exactly if it'll work for you. If not you can then figure out if it's worth simply replacing the RG-59 with something better (or at least newer). Since it's a receive-only application, it should be worth a try.

Other things to check for though is does this run go directly from the attic to the basement or does it go part of the way and then go through a splitter. Chances are you'll be good, but checking it out may save you some grief (Cable-TV systems send their signals using a wide swath of frequencies that overlap with many used by systems we like to scan). It shouldn't hurt the scanner connecting it to a live CATV coax, but you'll get lots of junk signals.

 

[KD0OTK]

Thanks for the reply. Checked and found a splitter. I replaced it with a coupler. I will have to climb up into the attic ( ugh ) and hook it up. I think my yagi will give me about 8db of gain, and the loss at 75 feet is 3db. I suppose 5db gain is better than a 800mhz radioshack rubber duck. Does anyone know what the gain of that antenna is off hand? I'll try it in the morning and report back.

 

[LtDoc]

I've yet to see any 'rubberduck' antenna have any gain at all. If anything, it'll be a negative gain, or a loss. If that directional antenna can't beat the rubberduck, there's something very wrong with that directional antenna.
Good luck.
- 'Doc

 

[bassinkoz]

you should be ok with rg-6, also do forget the db loss of having the antenna in the attic, oppose to having it outside, just a thought.

 

[kb0gus]

Hey guys. Kind of in a jam here. I get bad simulcast distortion from my local tower. I would like to put a yagi in the attic, but the only cable that runs to the basement is RG-59 for cable TV. I'm guessing there is about 50-100 ft of it. I've tested the antenna in the upstairs and it works great. Would the loss from the coax make it not even worth it? Forgot to mention above that this would be for a scanner.

Any luck with the Yagi on the simulcast system? I"m thinking of trying that as well.

 

[jim202]

Hey guys. Kind of in a jam here. I get bad simulcast distortion from my local tower. I would like to put a yagi in the attic, but the only cable that runs to the basement is RG-59 for cable TV. I'm guessing there is about 50-100 ft of it. I've tested the antenna in the upstairs and it works great. Would the loss from the coax make it not even worth it? Forgot to mention above that this would be for a scanner.

The problem with a simulcast system is trying to reduce the signal from other towers and look for the one nearest you. The yagi should help, but you may have to make several tries to find the right direction to point it in. You might have to actually point it some what off of your local tower to null out one of the other towers that is giving you problems.

Good luck with your efforts. I also hope that when you removed the slitter, that you replaced it with a barrel connector. The term coupler can take on several meanings.

 

[nanZor]

I just got burned on using pre-wired RG-59 cable with other barrel connectors designed for 50 ohm use. Found that the center pin on the 59 was microscopically smaller than the inside of the barrel center pins, and had reception intermittently - usually only when the 59 had sideways pressure on the adapters did it come alive.

What was frustrating was that the 59 center pin provided enough capacitive coupling to make me think connections were good initially as I could hear signals, but they were not as strong as they should have been.

I've sworn off RG-59, and will only use RG-6 as my minimum for quality and ease of use now...

 

[LtDoc]

Barrel connectors aren't that big'a deal. I haven't seen one yet that wasn't 'adjustable' for fit, making a good 'tight' connection. The 'receptical' part of them can be adjusted for a tighter fit or a looser one. As for the 50 ohm, 75 ohm thingy, it really isn't going to make much difference at all. I don't think it's worth worrying about. there are enough variations in impedances between different 'chunks' of coax that the connector's impedance isn't going to be anything special or unusual.
As for the differences between RG-59 and RG-6, either can certainly supply the required characteristics, but those characteristics are not the same to start with. Select whichever one best suits your needs.
- 'Doc

 

[nanZor]

As for the 50 ohm, 75 ohm thingy, it really isn't going to make much difference at all. I don't think it's worth worrying about. there are enough variations in impedances between different 'chunks' of coax that the connector's impedance isn't going to be anything special or unusual.

While I agree about the impedance not being that big of an issue for simple systems, this was a *mechanical* issue, where the specifications for 50 ohm connectors actually differ from 75 ohm connectors. In other words, if you ohmed out the cable, it would look open - YET, due to capacitive coupling, you could hear signals making you think that you had a solid connection.

I think the 50 ohm tee came from an old microwave adapter kit that had both 50 and 75 ohm versions with their differing center-pin diameters. We were warned not to mix them up back then. Now I know why.

 

[jim202]

While I agree about the impedance not being that big of an issue for simple systems, this was a *mechanical* issue, where the specifications for 50 ohm connectors actually differ from 75 ohm connectors. In other words, if you ohmed out the cable, it would look open - YET, due to capacitive coupling, you could hear signals making you think that you had a solid connection.

I think the 50 ohm tee came from an old microwave adapter kit that had both 50 and 75 ohm versions with their differing center-pin diameters. We were warned not to mix them up back then. Now I know why.

You have me confused as to why your saying that the use of the different connectors will give you an open if an ohm meter was used to measure the resistance of the cable end to end. I understand that there are some differences in the connectors, but I have never had a problem over the some 45 plus years I have been doing this.

 

[kb0nly]

You have me confused as to why your saying that the use of the different connectors will give you an open if an ohm meter was used to measure the resistance of the cable end to end. I understand that there are some differences in the connectors, but I have never had a problem over the some 45 plus years I have been doing this.

Because the 50 ohm couplers have a smaller diameter center contact to fit the 50 ohm coax with a smaller center conductor. I have seen this first hand also. I have also grabbed a F female barrel and tried to connect RG6 to it and it wouldn't fit on the center conductor, grabbed another and it fit fine. There is 50 and 75 ohm versions, or rather versions for large and small center conductor coax.