DB loss with this setup?

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intrepid97

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I have approximately 50ft. of RG-58 and 15ft. of RG-58 connected to a KB9VXR J-Pole and the coax is connected with a "barrel connector" to get the coax to my scanner. (was coming up just short of reaching scanner)

How much loss do you think I am suffering with this set up?

I was looking at 75ft. of LMR-400 and was thinking that would be the way to go?

This is connected toa PRO-164.


Thanks for any and all answers. :)
 

zz0468

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You're losing about 8.5 db for the coax at 850 MHz, and maybe two tenths of a db for the barrel connectors.
 

intrepid97

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I monitor mostly VHF and UHF.

I do believe I would do much better with the LMR-400? Or would another type of coax work fine if I eliminate the barrel connector?
 
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zz0468

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The barrel connector is the least of your problems. RG-58 is lousy coax for runs longer than a few feet at VHF frequencies and higher.

At 450, the loss is about 5.8 for just the coax. At 150, the loss is about 3 db. The barrel connector is a fraction of a db at those frequencies. At UHF and 800, changing out to LMR400 would bring a noticeable improvement. At VHF, there would be an improvement, but it wouldn't necessarily stand out like it would on the higher frequencies. But the goal is to eliminate as much excess loss as you can, because it does add up.
 

code3cowboy

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The LMR400 will give you a very noticeable improvement on the higher side of things, and an improvement on the VHF side. It is a fine choice for your application.
 

benbenrf

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Bin the Rg cable and invest in a single length of LMR 400 - you'll see a noticable signal improvement right across your bandwidth.
 
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Unless you are only interested in scanning a single specific band such as VHF, the J Pole isn't a good choice. A J Pole by design of the matching section doesn't do well on other scanner bands of interest, even at its design freuency is has no gain over a reference dipole anenna.
 

benbenrf

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Unless you are only interested in scanning a single specific band such as VHF, the J Pole isn't a good choice. A J Pole by design of the matching section doesn't do well on other scanner bands of interest, even at its design freuency is has no gain over a reference dipole anenna.
Agreed ......... it's essentially an antenna best constructed & sized for a specific bandwidth.
 
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