Coax loss question

[Rt169Radio]

Hello all,I would like to know which coax run would have the least signal loss.A 25 feet of RG-8X coax attached to a 6 feet of RG-8X coax with a double female UHF barrel connector to make a 31 foot run or just a 50 foot run of RG-8X coax?

 

[zz0468]

It depends on the frequency of operation, quality of cable, and quality of connectors. The 50' run has 2 db more attenuation than the 31' piece at 800 MHz. So, you have to ask yourself if 2 PL259's and a barrel are less than 2 db loss.

So, why not just buy the 50' piece, lop it off to 31' and put connectors on each end?

 

[Rt169Radio]

It depends on the frequency of operation, quality of cable, and quality of connectors. The 50' run has 2 db more attenuation than the 31' piece at 800 MHz. So, you have to ask yourself if 2 PL259's and a barrel are less than 2 db loss.

So, why not just buy the 50' piece, lop it off to 31' and put connectors on each end?

It will probably be used for a scanner antenna to scan 30-50 MHz

Of course everything will be good quality.

 

[LtDoc]

The only 'losses' would be from the connectors used to splice those cables. The amount of loss in a typical connector just isn't all that great at all, but there is some. I would think that sealing that splice would have more affect than the connectors themselves. Using just one run of feed line with no splices would result in lower losses, true fact. But then, just exactly how much 'loss' are you/we talking about? Typically, it's very small and usually not even noticeable. And of course that 'loss' is frequency dependent. The higher the frequency the more loss. In the range you specified, I really doubt if there would be enough loss to even be noticeable. And naturally, that assumes that you use good connectors applied properly. Eliminating losses is good. But there are practical limits to it.
- 'Doc

 

[kb2vxa]

Since connector loss is negligible and we're only talking one type of coax here one simple rule applies. The longer the run the greater the loss. Now you're probably asking yourself "When I ask the time why do these guys tell me how to build a clock?"

 

[Rt169Radio]

Thanks for the replys and info.