[TowerTalk] Coax

[Jim Brown]

On 4/8/2012 9:01 PM, Jim Thomson wrote:
> LMR-400db          .666 db
> LMR-400UF          .799 db
> RG-213U             1.024 db

RG213 is not a spec, it's a very broad generic description. There are 
RG213s built with thin copper braid and others with heavy copper braid. 
The loss in cable is a direct function of how much copper they use to 
build it.  Based on resistance data, Davis's 213 is directly equivalent 
to LMR400 for use on the HF bands.

##  say what.   Run 200 feet  of 213-U   into a dummy load at the far end, with a wattmeter 1 foot before the dummy load.


You'll need far more precise instrumentation than a Bird to measure a  
difference of 0.1 dB   Rather, you'll need a scope, RF voltmeter, or 
spectrum analyzer that can resolve 0.01dB, you'll need to measure by 
substitution, and you'd better make a bunch of measurements and compare 
them.

73, Jim K9YC