[AMPS] Delrin Spreaders

[Rich Measures]

>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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