Coax Calculation

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Well now that the snow has melted and the ground is defrosting a few inches every day it’s time to get into the full swing of my tower project.

My next step is to get my conduit installed and running my coaxes.  I have a good source to get the coax from so the sky is the limit…. Unfortunately the budget isn’t unlimited so that’s going to have to be part of my calculations.

Here is a table I did to compare the different coaxes running on 4 bands with the approx length that I am going to need to go from the tower to the shack.

This is based on 170′ of coax.

LMR-400 LMR-600 LDF4-50A LDF5-50A LDF6-50A 9913 RG8X
440MHz 4.516 2.891 2.436 1.354 0.959 4.791 13.473
144MHz 2.527 1.607 1.359 0.747 0.523 2.62 7.134
50MHz 1.47 0.931 0.789 0.431 0.3 1.505 4.019
14MHz 0.772 0.487 0.414 0.225 0.156 0.782 2.06

All the data was pulled from the Respective MFG websites. All losses are calculated in dB

Obviously the best choice is the LDF6-50A but at 13$ a foot it’s expensive stuff to run.

LDF5-50A is about 7$ a foot.  Still a little pricy but the loss is still quite considerably lower than it’s LDF4 counterpart.  LDF4-50A is about 3$ a foot.  Now we’re talking.  It closest loss cousin the LMR600 is about 1.75$ a foot. with about .3DB difference between the LDF4 and LMR600 I don’t think it’s worth twice the price.

Connectors are another factor in this equation.  The LMR600 connectors are about 20$ each for an N-Type, the LDF4 are about 25$.  In the grand scheme of things it’s not a huge difference.

Now that I have all my data lets put it all together.  I’d probably do 3 runs for the VHF/UHF stuff and 2 runs for HF

In total i’ll have 5 runs.  Lets forget the HF runs for the moment and look at the 2 contenders based on my budget.

The LMR600 vs LDF4-50A.

LDF4-50A x 510′ ( 3 runs of 170′ ) = 1530$ Plus 150$ in connectors bringing the total to 1680$
LMR600 x 510′ = 892.50$ plus 120$ in connectors bringing the total to 1012.50$

LMR600 wins by 667.50$….. is that worth the .3dB gain that I would get for the price? I could probably invest in a nice small amp for that price and compensate for the loss in the coax.


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