[Elecraft] OT; Feedline question

[Clay Autery]

Actually thermoplastics are NOT majority air....  I'm not an expert
here, but the dielectric constant appears to increase with thickness and
probably with density of the material.

Keep in mind that the standard insulation on THHN is 0.015"
thermoplastic (PVC) and that is covered by a 3-4 mill layer of clear
nylon to protect the insulation on conduit pulls...

I've given up trying to understand it all fully....

I've just decided to treat the entire feedline assembly from tuner
(radio) to antenna as a impedance matching network....
Bottom line....  getting the impedances in band to such a level that you
can tune it...

______________________
Clay Autery, KY5G
MONTAC Enterprises
(318) 518-1389

On 4/15/2017 8:02 PM, Wes Stewart wrote:
> Why do you suppose a little bit of dielectric on the wire would make a
> huge change, when the majority of dielectric is still air?
>
>
> On 4/15/2017 3:56 PM, Clay Autery wrote:
>> Thanks....
>>
>> So, these numbers are for BARE copper, right?
>> Using insulated wire changes things a bunch....
>>
>> For instance 18 GA THHN/THWN has an approx. dc of 2.35, XLPE has a dc of
>> 5 or so....  As the dielectric constant gets larger, things get real....
>> fast.
>>
>> 18 GA THHN/THWN...  (dc = 2.35 approx.)
>>
>> To get the same 464 Ohms, the Center to center distance must increase to
>> 7.52 inches or so...
>
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