[TowerTalk] Coax Loss -- RG-Numbers Don't Tell us Much

[Richard (Rick) Karlquist]

Jim Brown wrote:

> Not as ideal as you might think. The problem is that most coax is 
> shipped on reels with access to only one end. To make a transmission 
> loss measurement, you must unreel it to get a connector on both 
> ends. 

No, see below

> 
> Now, if you happen to own instrumentation that allows you to measure 
> that loss on a 1,000 ft spool from only one end, that's another 
> story. :) 

See below

> 
> 73,
> 
> Jim K9YC

I happen to own instrumentation that allows me to measure loss from
one end; it's called an MFJ-259B.  Cable loss is a built in function.
As long as the far end is open, cable loss is half of return loss.
You can also calculate loss from VSWR.  For example, 3:1 means your
loss is 3 dB.

Rick N6RK