[TowerTalk] Grey PVC Loading Coil

[Michael Tope]

----- Original Message ----- 
From: "Jim Lux" <jimlux at earthlink.net>

>>
>>I use black PVC as coil forms at 1200 watts on 160
>>with no problems.
> 
> Black PVC, or is it ABS DWV (drain, waste, vent), which is actually a 
> foam core, and even lower effective dielectric constant.  Although, 
> being black, and pigmented with carbon, and foam cored, it makes a 
> terrible insulator for HV use, particularly in electrostatic 
> machines.  But at the voltages you're likely to see in an antenna 
> system, it should be fine.  But in something like a Van deGraaff 
> generator with a few microamps at 500 kV, it is horrible.
> 

Solid Black PVC, not ABS DWV. My scientific material selection
process - found some laying on a shelf in the garage when I decided 
to make the coils. So far no fires. The one at the base of the antenna 
(I came up short on the center loading) shows absolutely no 
discernable self-heating after a long period of high-duty cycle 1KW 
CQing, so the unloaded Q of the inductor must be reasonably good.

73, Mike W4EF........................