>The whole "dissipation factor thing" seems to be an out-of-
>context explanation.
Bzzzzzzzzzzt. (cough, cough)
>We should really look to see ...
...snip...
>
>Dielectric loss relates to the electric field intensity in the
>material, as well as the dissipation factor. We ...
who is 'We'? I hope this doesn't turn out be like "They' during the
grate debate.
>... explain how "current
>flows through insulators" in the term of displacement current.
>It seems to me there is simply not enough displacement current in
>the Delrin to worry about, if the insulators are spaced along the
>line a reasonable distance.
- The issues are RF voltage gradient, and dissipation-factor at the
frequency thereof.
>
>While it is true the poorer dissipation factor would produce a
>few hundred times the amount of heat produced in ceramic dielectric
>under the same conditions, many times an insignificant quantity often
>remains insignificant
>
On 5 January 1997, Mr. Rauch stated that Delrin in a roller coil is an
"idiotic choice of materials".
>Perhaps Rich will show us his calculations that demonstrate the
>temperature rise and power loss would be significant, or explain
>what led him to his gut feeling?
>
My first experience with the significance of dissipation-factor was when
I used a General Radio Co. NYLON double-banana plug at the end of a home
made open wire feedline. The nylon melted and began foaming. I changed
the plug to one made from phenolic.
My second experience was with PVC pipe near the end of a 40m dipole. As
I was tuning up a home brew AB1/tetrode amplifier, the telephone rang.
My neighbor said: "Rich: your antenna is on fire." My gut feeling was
that the presence of flames and smoke indicated that it was quite
possibly on fire.
- [note: the amplifier was delivering about 1150v peak to the RG9
feedline at the time]
-Rich-
R. L. Measures, 805-386-3734, AG6K
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