On 2/8/20 8:57 AM, charlie carroll wrote:
I need some help selecting some type of material to build some custom
center insulators. I have what approaches zero experience in this area.
The insulators will be used to support near vertical dipoles for
160-meters. The antennas will be installed in the Caribbean and will
need high resistance to UV and salt water. I also want to install an
SO-239 and home made common-mode choke on the insulator. It would be
preferable that I be able to fabricate the final shape with common home
workshop tools and not have to rely on a machine shop. The insulators
won't be under a lot of tension because of their orientation, but low
weight material would be preferred. The insulators may be subject to
some winds containing sand particles.
I'm looking for some help selecting some appropriate material (UHMW,
Ultem, UV augmented HDPE, ...) that I can investigate further.
Most any UV resistant plastic would work. The shape is almost
immaterial, you can get flat bar stock, drill holes, and be done.
http://www.sdplastics.com/ultravioletresistance.html has a bunch of info.
I've used Acetal Copolymer (aka Delrin) with UV inhibitors. There's
decades of experience with it. Ultem is very good (we use it on
spacecraft), but probably costs more than what you want.
Looking at the McMaster Carr catalog, i see they they have a VHMW
Polyethylene which is weather resistant. I'm not sure that I'd use PE
though.
Speaking of machine shops - you might look at one of the prototyping
companies like First Cut Protolabs:
https://www.protolabs.com/services/cnc-machining/ - there's a fair
number of these places around, and they typically stock all the useful
materials, and will turn it around in a few days.
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