>G10 will melt down into an awful stinkin' and
>burnin' mess when heated in high Rf fields. I
>rarely use it anymore, except for PW
>applications. It is certainly a big step above
>Delrin acetals or nylons.
>From experience, G10 is ok for HF potentials of c. 6000V-rms.
>Have settled on several
>wonder materials like:
>Rexolite (crosslinked polystyrene) rod and sheet
>Polyetherimide (ULTEM* 2300) with 30% glass, also known as Tempalux*
>Polysulfone (UDEL*), also known as Thermalux*
>G7 (silicone resin reinforced glass)
>
>All more expensive, but if you want the highest Q
>and no heating, they are worth it. These are all
>high temperature engineered plastics. If you are
>concentrating E field flux in the dielectric,
>even with a kW, G10 will heat up. Good old UHMW
>(ulta high molecular weight) polypropylene and
>polyethyline made good insulators but have low
>glass transisition temperatures and will soften
>and dimensionally change with heat.
>
>Your local plastics supplier has them. Pricewise,
>the first two are about $1000 for a square foot
>of 1 inch thick material! The rod stock is much
>cheaper, and for smaller coils it is more so. The
>G7 is more difficult to machine or turn on a
>lathe than G10 due to the lamination layers. But
>it is excellent material structurally as well as
>RF'ly.
>
Tnx, John - but you live in a taller forest than the rest of Hamdom.
>John
>K5PRO
>
>Rich AG6K said:
>> I bought 50-lbs of porcelain clay and I tried making porcelain
>>pottery. The shrinkage factor is about double ordinary stoneware clay,
>>and porcelain clay is hellish to work with. My advice is use G-10
>>fiberglass-epoxy for insulating. It's good around RF, strong, and easily
>>drilled/machined.?
>>
>>>My YL has a ceramics business, and I started thinking about trying to
>> >manufacture my own ceramic (porcelain) insulators. Has anyone tried this?
>
_______________________________________________
Amps mailing list
Amps@contesting.com
http://lists.contesting.com/mailman/listinfo/amps
|