Preassembled coax cable

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Rt169Radio

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Hello,I was wondering if the preassembled RG-8X coax's in this link could be used for outdoors? Their listed as coaxial “jumper” cables to attach to accessories that are attached to coax coming from a antenna,and am not sure if they can be used outdoors as coax coming from a antenna.

Coaxial Cable, Coax Cable Preassembled
 

ridgescan

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Sure you can use the longer runs for the antenna. Only trouble is getting the larger connector at one end through whatever hole into the home. That's why a lot of us build our own connectors once the cable is routed in.
 

Rt169Radio

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Sure you can use the longer runs for the antenna. Only trouble is getting the larger connector at one end through whatever hole into the home. That's why a lot of us build our own connectors once the cable is routed in.
Okay,thanks for replying.
 

mpddigital

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Coax assemblies

Depending on your set-up RG-8x might be fine. It is an old standard though and varies greatly in quality by producer. The cheap chinese stuff is not worth squat. Look for Alpha, Coleman, or other US producers and stay away from Radio Schlock and other cheapos.

8x is fine for up to about 300MHz. If you are going up to 900MHz you really need to look at some of the coax designed for higher freqs. you can look at the Times Microwave loss calculation tool to find out how different types will perform for your needs. There are a lot of good cable manufacturers to pick from, and the price doesn't have to be high.

One option if you need to run a cable into the house and don't want a big hole is to come in thru a roof vent or order on end stripped with a clamp connector you can install yourself. Don't apply a crimp connector without good tools.
 

Rt169Radio

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I have another question,how much of a signal loss would I have if I ran 25 feet of RG-8X coax from a 2/440 antenna and then attached 13 feet of RG-58 coax to it,I would either use the antenna for scanning or transmiting.

25 feet of RG-8X has a efficiency of 77.4% and 13 feet of RG-58 has a effciency of 84.8% ,this is calculated at the freq of 144 MHz
 

LtDoc

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I have no idea how you've arrived at those 'efficiency' figures, but my first guess would be to average the two and see if that's acceptable to you.
Your proposed feed line would be usable. Not the 'best' in the world, but usable. I won't even try to figure what kind of 'loss' you might have with it, just too many variables.
- 'Doc
 

mmckenna

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I have another question,how much of a signal loss would I have if I ran 25 feet of RG-8X coax from a 2/440 antenna and then attached 13 feet of RG-58 coax to it,I would either use the antenna for scanning or transmiting.

25 feet of RG-8X has a efficiency of 77.4% and 13 feet of RG-58 has a effciency of 84.8% ,this is calculated at the freq of 144 MHz
Not sure where you got those numbers either. You weren't looking at velocity of propagation numbers, where you?

Anyway, at 144MHz, here it is:
25 feet of Belden 9258 RG-8x = 1.013 db of loss
18 feet of Belden 8240 RG-58 = 0.604 db of loss
Figure .4 db in connector losses for the joint where the two meet, and you are looking at 2.017db of loss. The .4db number may be slightly off, but it isn't going to change much.
If your entire cable run is the 43 feet, then 2db of loss isn't too bad. You can certainly do better, but no matter how much you spend, you'll always be able to do a bit better. Use a dual band antenna with some gain, and you'll overcome the feed line loss. Losses are going to be worse on the UHF side, totaling 3.588. Consider that loosing 3db is loosing half your signal. Again, a gain antenna will overcome some of this. If at all possible, I'd stick with at least one cable type to eliminate the small connector loss, or try and go with a larger/lower loss cable all the way through.
 

Rt169Radio

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Not sure where you got those numbers either. You weren't looking at velocity of propagation numbers, where you?

Anyway, at 144MHz, here it is:
25 feet of Belden 9258 RG-8x = 1.013 db of loss
18 feet of Belden 8240 RG-58 = 0.604 db of loss
Figure .4 db in connector losses for the joint where the two meet, and you are looking at 2.017db of loss. The .4db number may be slightly off, but it isn't going to change much.
If your entire cable run is the 43 feet, then 2db of loss isn't too bad. You can certainly do better, but no matter how much you spend, you'll always be able to do a bit better. Use a dual band antenna with some gain, and you'll overcome the feed line loss. Losses are going to be worse on the UHF side, totaling 3.588. Consider that loosing 3db is loosing half your signal. Again, a gain antenna will overcome some of this. If at all possible, I'd stick with at least one cable type to eliminate the small connector loss, or try and go with a larger/lower loss cable all the way through.
Thanks for the info,I got those efficiency figures from the times microwave coax calculator.
 
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