Just out of curiosity - Did anyone ever try a cabinet-sized or
room-sized cavity resonator as roof filter in a HF receiving system?

I've trawled a bit for construction details, and found that a squat
cylindrical resonator may have a radius of a quarter wave, so say...

IF, MHz Diameter, feet what on earth?
-----------------------------------------------------
100 .49 a big can?
45 11 a fuel tank?
9 55 ????

It would be cool to use a whole room as a resonator, adding furniture
or guests as a way of trimming frequency or Q factor.

For mobile use, one might consider using a whole truck trailer as a
resonator.

I would not mind dumping a truck trailer behind the sheds at my
parents' farm and running some coax there and back, for a bit of HF
work during my weekend visits. Besides, they also have a couple of
unused silos, with cavities 15 ft in diameter and about 40 ft height.
I wonder if such cavities in series would be tight enough to provide
enough selectivity for CW work. They also have a huge pistoning lid
hanging inside from a crane, which could be used for tuning. So
perhaps they could provide ALL the filtering right at the fundamental
frequency, like: rhombic antenna - coupler - silo 1 - coupler -
silo 2 - coupler - product detector - audio chain. Too bad they're
reinforced concrete and would need lining. A neighbour & friend has
new, shiny, airtight aluminum ones. His son is an electrical
engineer. Hmmmm.


Please do laugh, but comment constructively! I am an ignorant
coil-winder. Where do I read up on resonators and coupling? I would
not mind experimenting with a stack of barrel-sized filters if the
numbers warrant it.

73

Filippo
N1JPR/I2