[Lowfer] Interesting finding

[Ed Phillips]

Bill Ashlock wrote:
> 
> Stewart, John, Dave, Dale, Mike, and all super high-Q capacitor users:
> 
> Thanks for the advice on a better cap than mica. I will check these out
> tonight as I have some in my 'overstocked surplus warehouse' (should anyone
> be a 'Bob and Ray' fan from way-back <G>).
> 
> I'm going for a capacitor Q  >10x the Q of the actual loop and his puts me
> in the 8000 region (yeah that's 8 thousand!). The latest measurements
> indicate a combined Q for the test loop and cap of 835. The normal goal of
> transmitting mica design is to keep the temperature low enough to prevent
> damage to the capacitor or prevent a large change in capacity - so heat
> sinking appears to be important. This isn't exactly my design goal at .1w.
> <G>
> 
> I'm beginning to wonder if any cap using thin aluminum will work in this
> application.
> 
> Bill A

	A Q of 8000 with a LOSSLESS loop would still mean a dissipation factor
of 0.000125 for the capacitor, or less than the dissipation factor I can
find listed for any mica type.  A good EXTENDED FOIL polystyrene
capacitor (or group in parallel to reduce the effects of lead
resistance) is probably your best bet but still can't make it.  In
principle an air-dielectric capacitor might, but it would be enormous.

Ed

Ed