Richard Clark wrote:


Black is usually indicative of carbon content; but I wouldn't let that
stop me the first time around if it was handy (pop it into the
microwave and nuke it to see if it gets hot - this is not about
microwave frequencies, merely tendency to conduct and to dissipate).

Wouldn't sticking my multi/ohmeter into the material at a couple of points
tell me if it dielectric or not? I did that and it would seem that this black
poly pipe is totally non-conductive. If it contained carbon it would be like
a composition resistor and register something (no?).

Anyway I am working on another source of rigid 3/8" dia. UV/PVC which might
work out better.

bill

On Sat, 17 Apr 2004 20:28:35 GMT, zeno wrote:
Richard Clark wrote:

Black is usually indicative of carbon content; but I wouldn't let that
stop me the first time around if it was handy (pop it into the
microwave and nuke it to see if it gets hot - this is not about
microwave frequencies, merely tendency to conduct and to dissipate).

Wouldn't sticking my multi/ohmeter into the material at a couple of points
tell me if it dielectric or not? I did that and it would seem that this black
poly pipe is totally non-conductive. If it contained carbon it would be like
a composition resistor and register something (no?).

Anyway I am working on another source of rigid 3/8" dia. UV/PVC which might
work out better.

Hi Bill,

Being conductive and being lossy are not the same thing. You may have
both situations, or one, or the other; however "not being conductive"
does not necessarily mean "not lossy." The microwave test is hardly
conclusive unless you notice it heat up. Other testing is more
sophisticated.

73's
Richard Clark, KB7QHC

Being conductive and being lossy are not the same thing. You may have
both situations, or one, or the other; however "not being conductive"
does not necessarily mean "not lossy." The microwave test is hardly
conclusive unless you notice it heat up. Other testing is more
sophisticated.

73's
Richard Clark, KB7QHC

Ohhhhh! I get it now. Its like why some kitchenware is ok for the microwave and
some not. The RF might be heating my spacers and if the spacers are the wrong
stuff, we have a melt down! Darn....why did all those neat industries making cool
things out of glass and ceramic dry up and disappear.....

with the collectible price of simple glass antenna strain insulators you would
think some industry would fire it up again, and while they are at it they could
make some of them out of purple glass and the collectors would go nuts unleashing
all kinds of cash on them. How hard is it to make things out of glass?

ps. has anyone actually heard of a diy ladder line having a spacer melt down
while running power? no reason why it couldn't happen....

Now that I understand, I will at least put my prospective spacers through the
microwave test....

-bill

On Sat, 17 Apr 2004 23:38:29 GMT, zeno wrote:
ps. has anyone actually heard of a diy ladder line having a spacer melt down
while running power? no reason why it couldn't happen....

Hi Bill,

This has never been reported here. Instead, it is noted by the
characteristic Z of the line being lower than computed. Such
measurements (of the characteristic Z) can be performed through a few
simple but still time consuming tests.

73's
Richard Clark, KB7QHC

Anyone tested that gray UV resitant PVC pipe? What about that for ladder line
spacers?

-bill

Richard Clark wrote:

On Sat, 17 Apr 2004 23:38:29 GMT, zeno wrote:
ps. has anyone actually heard of a diy ladder line having a spacer melt down
while running power? no reason why it couldn't happen....

Hi Bill,

This has never been reported here. Instead, it is noted by the
characteristic Z of the line being lower than computed. Such
measurements (of the characteristic Z) can be performed through a few
simple but still time consuming tests.

73's
Richard Clark, KB7QHC

On Sun, 18 Apr 2004 02:36:42 GMT, zeno wrote:
Anyone tested that gray UV resitant PVC pipe? What about that for ladder line
spacers?

Hi Bill,

Each formulation seems to be distinct, but offhand I don't recall
which is which. To broaden your experience with this forum, visit:
http://groups.google.com/groups?oi=d...mateur.antenna
and checkout their advanced search page. Use "PVC" and "Loss" as
keywords in the search. The topic is not so novel as to be sparsely
represented in the archive.

73's
Richard Clark, KB7QHC

Hi Richard,

Thanks for the link to the archives, I will check it out.

I imagine there a few hams who want to make their own ladder line these days.
Other than finding some vintage ceramic spacers (rare) what are they using?

Apparently paraffin soaked dowels are not without some shortcomings. I think
there is at least one ham who has a cottage industry selling his homemade version
ladder-line which, from what I can gather, utilizes the black poly piping that I
mentioned earlier.

I think I came across at least one ham who has used the grey UV/PVC pipe which he
slices (saws) lengthwise and then drills holes and/or notches etc. This seems a
bit labor intensive if one wants to make any quantity, but maybe not as much as I
think.

If the UV/PVC pipe is a good solution, I might be able to track down a source of
3/8" UV/PVC pipe which I would not slice up, but just cut into 6" lengths and
then devise a fastening system on either end for the wire.

Bill

Richard Clark wrote:

On Sun, 18 Apr 2004 02:36:42 GMT, zeno wrote:
Anyone tested that gray UV resitant PVC pipe? What about that for ladder line
spacers?

Hi Bill,

Each formulation seems to be distinct, but offhand I don't recall
which is which. To broaden your experience with this forum, visit:
http://groups.google.com/groups?oi=d...mateur.antenna
and checkout their advanced search page. Use "PVC" and "Loss" as
keywords in the search. The topic is not so novel as to be sparsely
represented in the archive.

73's
Richard Clark, KB7QHC

"zeno" wrote in message ...
Anyone tested that gray UV resitant PVC pipe? What about that for ladder
line
spacers?



I can't say that I tested it but I have an 8 element 220 mhz beam on a 10
foot piece of the grey electrical conduit that has been up over 15 years. I
think it is about 1 1/2 inches in diameter.