Topband: 1000 feet 5/8" hardline or 600ohm True Ladder line.

[Jim Brown]

On 4/26/2014 8:21 PM, Mike Waters wrote:
> You're right about the loss being all in the copper center conductor, Jim.

AND in the shield. One of the things that gives bigger coax lower loss 
is that skin effect has the greater diameter of the shield to work with.

It's important to realize that "RG6" and "RG213" are no longer 
specifications for the cable that we buy. There are, for example, 
several dozen RG6s in the Belden catalog, many very different from each 
other. Ditto for RG8, RG11, RG58, RG59, RG213, etc. You've got to look 
at the mfr data sheets to find the real specs.

Example -- go to the Belden website and compare 9212, 8213, 9913, 
9913UF. Very different construction, very different loss 
characteristics. All "RG11" (although I've seen 9212 described as RG11 
in older catalogs and RG6 in at least one newer one). I've got a big 
spool of 9212, and it's slightly smaller than  most RG11, but a lot 
bigger than any RG6 I've ever seen.

I haven't seen Owen's charts, but there's a good chance they're out of 
date in that respect.

For cables of approximately the same o.d. a pretty good determinant of 
loss is DCR of the shield and center combined, because resistance at RF 
is that DCR multiplied by skin effect. Cables with Cu clad Al, like 
LMR400, are an exception. By the time you hit 2 MHz, it's equivalent to 
solid copper. But NOT for Cu clad steel -- it doesn't get close to to 
solid Cu for another octave or two. (an octave is double the frequency).

There's more detail about this in k9yc.com/Coax-Stubs.pdf

73, Jim K9YC