RadioBanter - View Single Post - Fuel Tanks and Cereal Silos as Cavity Resonators for HF

September 25th 03, 12:45 AM

In article , (Michael Black) wrote:
SpamLover ) writes:
Just out of curiosity - Did anyone ever try a cabinet-sized or
room-sized cavity resonator as roof filter in a HF receiving system?

Someone did some work with 10meter cavities out of oil drums. He
wrote about it in 73 back in 1970 or so. But his goal wasn't
the cavities, but some weird modulation scheme that I'm not sure
really made sense, so I don't think the articles gave a lot of
detail to the cavities, and since the whole thing seemed hair-brained,
it might not be the best source of experience on HF cavities.

In the June (or maybe it was May?) 1972 issue of QST, there was
an article about making a filter out of a metal garbage can for
2meters. But of course, at those frequencies, a cavity is not
an exceptional sight.

There have been some articles, in QST and I think Ham Radio (in
the mid-seventies) about HF helical coils. That sort of filter
might be more realistic than a cavity at HF.

At a ham flea market some years back someone was selling a 10m cavity -- I
think it might have started life as a hot water tank.

Dr. G.

Michael VE2BVW