Topband: Measured RG-6 Loss: Solid Copper vs. Copper Clad center conductor

Tom W8JI w8ji at w8ji.com
Fri Jan 25 12:37:46 EST 2013


> Its easy to use an MFJ-259 to quickly check cable loss, using its cable 
> loss mode.  Its more accurate if you build or purchase a simple 50:75 ohm 
> broadband matching transformer.
>

The 259B uses 1/2 of open circuited return loss as transmission loss. This 
only works if the line impedance matches the bridge impedance of the 259, so 
it only works with 50 ohm lines.

75 ohm lines would need to be measured some other way. I have my network 
analyzer set up to output files now, and eventually plan on measurements. 
I'm too busy with work now, but someday in the not too distant future I want 
to do that project.

I ran several tests, and the network analyzer (a real one, not a $500 one) 
is by far the most accurate method and fairly easy to get data into 
spreadsheets for processing.

73 Tom 



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