>> > >> It seems, on the surface, that one could dip a small air variable in
>> > >>(pure) water and have a high voltage part with 80x the capacity of the
>> > >>original.
>> >Or, if not water, some non-conductive liquid. Don't have a dielectric
>> >chart handy, but there must be something suitable.
>> Transformer oil (or nearly any mineral oil) would work quite well. The
>> dielectric constant typically is just over 2.0, and the voltage insulating
>> characteristics are excellent. A good application would be for the tune
>> cap on 160 or 80 meters : a 150 or 200 pf, 1000V air variable would become
>> a 300 or 400 pf HV variable cap.
>When you look around and see the industry avoiding a method
>there is almost always a good reason. In this case they are
>probably concerned about loss of Q and heating of the component.
>Dissipation factor is the ratio of energy dissipated to energy stored
>per cycle. The dissipation factor would increase greatly if you pick
>the wrong material.
>As a second effect when you add a dielectric, energy is more
>concentrated. There is more current in a smaller area. That also
>can increase losses if you don't plan for it.
/\ So make the plates out a good conductor.
>A third effect is drift. The component will change values with
>You need to look at more than capacitance.
>Many materials also have an increase in dissipation factor with
/\ good points, Mr. Rauch. If there had been something better, Joe
Jennings would likely have chosen it over the vacuum dielectric in his
- R. L. Measures, 805.386.3734,AG6K, www.vcnet.com/measures.
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