[time-nuts] Re: Potting compound advice needed

[Lux, Jim]

On 11/10/21 2:40 PM, Richard (Rick) Karlquist wrote:
> I am looking for help choosing a potting compound that
> has the following properties:
>
> 1.  Good for 5,000VAC @ 1 MHz
> 2.  Low RF losses.
> 3.  Low permittivity is preferred
> 4.  Low tempco of permittivity is a want.
> 5.  Something I can implement in my home shop
> without access to a vacuum pump etc. is a want.
>
> Thanks in advance
>
> Rick Karlquist N6RK 


After consulting the experts at work, what they use for this kind of 
thing (HVPS, high power RF, etc.) is:


https://www.elantas.com/pdg/products/tooling-composites-materials/gel-encapsulants-sealants.html

Elantas EN-11 (Conap) Casting, Potting and Molding Compound.

epsilon of 2.9 @ 1 MHz

610 V/mil breakdown

tan d of 0.009 at 1 MHz

8 hour cure at 80C, more than a week at 25C. 50 min pot life


your challenge may be finding it in small quantities - a casual search 
shows gallon cans at just under $200, and I'm not sure that you don't 
need to buy a part a and a part b.