[TowerTalk] Plastic Cutting Boards for Antenna Stuff ?

[Jim Lux]

On 4/22/12 7:14 AM, Bill Harris wrote:
>
> Zapping a piece of material in the microwave for a minute or so, should give you some idea what the insulating properties are.  If it doesn't get hot, (how hot?) it should be okay for an insulator at HF frequencies, right?
>

I've used a lot of cutting boards as HV insulators..

the microwave test is sort of so, so.. it's at 2.5 GHz and it more 
measures RF absorption than things that are actually more important like 
HV breakdown and water absorption.


If the cutting board is white high density polyethylene, it makes a fine 
insulator for HV (and RF).

It *does* have a low melting point.   This is handy when you want to 
weld it, not so handy when machining it. If you want to use tools that 
"cut", nice and sharp is needed.

It saws about like wood, so use a wood saw, not a hacksaw. A hole saw 
works pretty well.  Keep the tool cool, so the plastic doesn't melt.

Passing a torch over the cut edge will "fire polish" it and take off 
rough edges and sanding marks.  (this works real well for acrylic and 
polycarbonate, by the way)


Most of the HDPE is not UV inhibited, so it might breakdown in a few 
years (your mileage may vary.. I've got some chunks that have been 
outside for getting on towards 10 years in SoCal sunshine, and they look 
fine)