Hardline / Coax loss calculator
I got a few questions at Field Day 2017 why I always run the heavy thick RG-213 cable for HF when we are portable. I told them it was all about the loss and the shielding.
Below is good information to have handy when looking at purchasing new coax or hardline. Remember: When it comes to coax, you definitely get what you pay for.
As a rule of thumb, try to keep coax losses under 1db in your antenna setup.
3db loss is HALF you power!
(Yes, some of these are similar.. pick the one you like and go with it. Or bookmark this site and have a choice of any of them.)
http://kv5r.com/ham-radio/coax-loss-calculator/
http://www.w4rp.com/ref/coax.html