At 07:34 PM 3/10/98 -0600, you wrote:
>>         Secondly, lets suppose that there was enough wire in the cable to
>create
>>a significant capacitance. The effective circuit would look like a
>
>RG-58 is about 30 pF/foot, according to my Belden catalog.
>
>

Ok, maybe I was getting confused, I thought we were talking about single
conductor wire (loosely called cable). Of course, my whole discussion would
be incorrect for coax. Jorge has mentioned that this phenomenon is
observable when dealing with power transmission line. Power transmission
line is not coaxial, is it? I have always been told that it is single
conductor woven cable, sometimes with a hollow core with a coolent run
through it.

>>capacitor with a resistance in parallel (we can ignore the inductance, it
>>certainly won't make much difference beyond seconds of time). The value of
>>the effective parallel resistance can be approximated by the resistance of
>>the cable. Assuming the cable is copper and of a resonable diameter, lets
>
>Sorry, if you take a hunk of coax with both ends open, any parallel
>resistance _across_ the cap has to be from the insulation resistance of the
>dielectric.
>
>I don't have any teflon coax, but I'll bet it makes a _very_ good
>low-leakage cap.
>
>Look, at low frequencies, the capacitance of coax is like any other cap.
>It stores a charge.  Put enough voltage across that cap and it can bite
>you.  Use a high-quality dielectric and the stored charge will be there for
>quite some time.
>
>

Yes, I understand this, but as I said above, I thought that you meant
single conductor. I think the original author was refering to single
conductor wire, or at least was initially interpreted as such. The reason
for the resistance in parallel with the cap. is that you can view a single
wire as split up into elements, each one forming a plate of a capacitor
with adjacent elements as the opposite plates, and each little element
forming a little resistance. I then mentally integrate over the length of
the cable to form an electrical picture of what is going on.

>>for an extream example. The spool of wire holding 10 miles of wire would
>>probably barely fit on my desk. So, I guess if you had a huge spool, you
>
>I've got a spool that's about 26 miles long, and it isn't very big.  It's
>not coax, and it's only 34 gauge.  Too bad I don't have access to both
>ends--it'd be a neat inductor!
>

Wow, I bet it would be! Even better if you stuck a core in it!

>
>newell
>
+--------------------------------+
| Sean Breheny                   |
| Amateur Radio Callsign: KA3YXM |
| Electrical Engineering Student |
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