On 10/6/2013 2:32 AM, wrote:
On Saturday, October 5, 2013 7:44:30 PM UTC-5, Jeff Liebermann wrote:
On Sat, 05 Oct 2013 15:24:01 -0500, John S

wrote:



The microwave oven test is not very useful. The microwave will test

whatever at about 2450MHz. I doubt he is trying to make a loading coil

for anything near that frequency.



Actually, it's very useful. In my admittedly limited experience,

anything that survives the microwave oven test, will usually work

nicely at HF frequencies. Those that get warm in the oven, might

work ok. Those that melt, burn or explode, will probably not work

very well at HF. While testing at 1000 times the frequency, and 30

times the power, might be considered overkill, it does yield some

useful information.

I had always heard that if one were to use PVC, the gray type was
the best vs the white. I've used gray PVC for mobile whip loading
coils for years and never really noticed any real problems.
But, I do not run high power, and 100w is the max I run.
I've always had good results with the antennas, and noticed no
noticeable performance loss vs say an open type bug catcher coil.
There may be some, but it's small enough not to be a problem.

When I first started using the gray PVC, I stuck it in the
microwave with a glass of water, and it did not get warm at all.
I have heard the white PVC can be more of a problem.


The guys that build high Q inductors for crystal radios use
styrene pipe couplers.
http://www.genovaproducts.com/docs/P...og.pdf#page=37
Note: S prefix denotes styrene.
I see references to both Lowes and Home depot having these in stock.
I think styrene will deform at a lower temperature than PVC.
Mikek