John, A 16' long ferrite loop sounds incredible. It must have been a wave magnet extraordinaire. There has been an ongoing thread at RapNTap, an xtal radio site, regarding ferrite cored air coils made of high count litz. The Q of some setups is through the roof. *http://tinyurl.com/3dnu6o*
It's not just the Royale with Cheese (pocket weasel) that does well with the little ferrite antenna I built. My Sony 2010's large ferrite gets a big kick as well. Yesterday, with the 2010 on the turntable mid day, I tuned in Miami 710, which is over 400 miles away. I could barely hear a signal, one led on the 2010's strength meter was flickering. With the tuner peaked, the 6 led's lit up and the signal disclosed very clear audio. More on the Royale with Cheese: http://www.youtube.com/watch?v=SLtwFugudZE 73 Gil On 1/12/08, John H. Bryant <[EMAIL PROTECTED]> wrote: > > > > One of the first things that I thought about when Gary first infected > me with this disease was inductively coupling a major piece of > ferrite, possibly tuned, to one of these little beauties. Gil Stacy > has already done that, of course, and has uploaded a very nice > article to Ultralight Radio Files area of DXer.ca. I'll be uploading > an article to the files sometime in the next several hours that you > might also find helpful > > Almost 15 years ago, LWaver Bill Bowers and I set off on a quest to > learn about Ferrite loops and to build the world's largest. We built > a number of prototypes and smaller antennas before building "The > Monster" that is about 4" in diameter and 16 feet long! It tilts and > turns like other smaller ferrite loop antennas and is a wonder to > behold. Bill spent a lifetime working professionally with very weak > AC currents, magnetism and coaxial cables and was the prime mover on > this project. I was project scribe, carpenter and provided a (then) > strong back. > > Unfortunately, Bill moved to Houston from his home near me here in > central Oklahoma and took The Monster with him. I still have a I" x > 4' tuned/amplified loop antenna and, ahem, several pieces of "spare" > ferrite. I'll be mating some of those to ultralights in the future. > > In the meantime, here are some of the things that we learned in our > project: > > 1. The antenna of a ferrite loop is NOT the ferrite, but rather the > coil wound around it. We found that the best coils were single layer > coils from high wire count Litz wire, spaced off the ferrite about > one wire diameter, with the turns spread apart about one wire > diameter. The closer we came to those rules of thumb, the higher Q > was the coil... Higher Q coils tune more sharply. However, a solid > core hook-up wire is a great place to start and can be used to create > a fine antenna. > > 2. The gain of the antenna is roughly proportional to the amount of > ferrite. > > 3. The sharpness of the nulls is roughly proportional to the > slenderness of the ferrite mass.... skinnier=sharper nulls. > > 4. It is possible to bind groups of smaller ferrite bars together to > make a larger bar (we did that a lot.) HOWEVER, if the bars are > placed end to end, the ends must be square, flat and very > smooth. The goal is to have not even 1/100 inch between the ends.... > NO GAP AT ALL. Bars may be bundled together in odd numbers... but the > geometry must be very tight, like a wire cable in cross-section. You > may bundle and place end to end to create a long, fat bar. If you do > so, it is important to stagger the gap locations of the end to end > bars. My own 4-footer is 3 bars in a triangular bundle. It is made of > a dozen 1/2" diameter bars very carefully placed and wrapped with tape. > > Anyway, if you are thinking of moving into the Super Modified > category of Ultralight Radios, Gil Stacy's article and mine will be > of some interest, I think. I'll upload the Bowers-Bryant article > sometime yet today and inform the group. It is a reprint from the > Proceedings of Fine Tuning in 1994-95. > > > John B. > Stillwater, Oklahoma, USA > Rcvrs: WiNRADiO 313e, Eton e1, NRD-535(kiwa-mods) > Antennas: 700' NE/SW mini-Bev, Wellbrook Phased Array (pre-production > version) > > > _______________________________________________ > IRCA mailing list > [email protected] > http://montreal.kotalampi.com/mailman/listinfo/irca > > Opinions expressed in messages on this mailing list are those of the > original contributors and do not necessarily reflect the opinion of the > IRCA, its editors, publishing staff, or officers > > For more information: http://www.ircaonline.org > > To Post a message: [email protected] > > _______________________________________________ IRCA mailing list [email protected] http://montreal.kotalampi.com/mailman/listinfo/irca Opinions expressed in messages on this mailing list are those of the original contributors and do not necessarily reflect the opinion of the IRCA, its editors, publishing staff, or officers For more information: http://www.ircaonline.org To Post a message: [email protected]
