A reasoning on coaxial cables
 

On Sun, 7 Jun 2009 09:35:15 +0200, "Antonio Vernucci"
wrote:

the 0.8 ohm per meter figure was not taken a by a catalog. It simply comes from
dividing the measured DC resistance of my RG-179 cable roll (which is 25 ohm)
by its length (which is 30 meters).

Hi Tony,

Then you are suffering from one of two problems:
1. Your measurement is seriously in error, or
2. Your cable is from a very poor vendor, or
3. You have reported the wrong type of coax.

All that aside, the reason why it is specified as any specific Z has
been well described. If you take issue with any "one" measurement of
R that seems to confound those descriptions, then "any" measurement of
R would do so, likewise.

In other words, ALL cables exhibit the loss of R. There are coaxial
cables that are very much smaller than yours that are employed in
transducer probes for doing ultrasound scans of patients. You would
need a microscope to measure their dimensions. And they have enormous
loss.

73's
Richard Clark, KB7QHC

A reasoning on coaxial cables
 

Hi Tony,

Then you are suffering from one of two problems:
1. Your measurement is seriously in error, or
2. Your cable is from a very poor vendor, or
3. You have reported the wrong type of coax.

Look at http://hongsencables.hisupplier.com/...TFE-Cable.html and
you will see that the RG-179 cable has a Direct Current Resistance (DCR) of 800
ohm / kilometer, that is 0.8 ohm per meter, exactly what I measured. That is the
normal resistance value for a 7-wire stranded copperclad conductor, each wire
having a 0.1 mm diameter.

Should you think that the Chinese firms are poor vendors, then read the
characteristics of the US-made RG-179 built by Belden on
http://us.100y.com.tw/pdf_file/Belden%2083264.pdf, where they report a
resistance of 244 ohm per 1000 feet, that again corresponds to 0.8 ohm meter.

Regards

Tony

A reasoning on coaxial cables
 

On Sun, 7 Jun 2009 23:17:19 +0200, "Antonio Vernucci"
wrote:

copperclad conductor, each wire
having a 0.1 mm diameter.

Ah! Steel.

Nevermind.

73's
Richard Clark, KB7QHC