Hello Again Rick, After adding three more turns of #18 wire to the 9' LW box loop, I now have 567 feet of wire in 22 coil turns, and a tuning range from 142 to 350 kHz. This should be OK for DX testing, so I'll probably wrap it up this way. It's amazing how much wire you need to add to get the tuning range a little lower, on LW. The coil turn spacing on the loop is actually wider than .25 inches, because although that was the width of the wooden spacers used with the circular saw to cut the wire slots, I forgot to account for the kerf width of the circular saw blade. The actual coil turn spacing is about .4 inches. The variable cap used in this project (and all the PVC loops) was a compact, 8:1 vernier drive single-section unit from the eBay seller "crystalradiosupply." This split-stator cap fits neatly inside of a section of 1.5" diameter PVC pipe, for waterproofing the loop tuning system. This LW box loop project was essentially an afterthought, after the construction of ten MW PVC-frame box loops of various sizes. The mail goal of the project was to design and test lightweight, structurally strong PVC frames for extremely large loop sizes-- a goal which was entirely successful. Refinements to some of the larger loops can probably be made for optimum performance, and I'm happy that Steve R. has expressed interest in making one of these LW box loops according to my design, for testing against his 1600' long wire. Living on a residential lot of .33 acre, I don't quite have the experimental freedom that he has, in deploying sizable LW antennas. 73, Gary In a message dated 5/4/2009 12:08:52 P.M. Pacific Daylight Time, k...@charter.net writes:
d1028g...@aol.com wrote: > The design was a basic one-loop coil system in a traditional box loop > (non-spiral) design, wound on a PVC support frame, tuned by a 4-400 pf capacitor > connected directly at the coil ends. Is that a split-stator of a single-section cap? > The coil windings are spaced by slots > cut in short sections of PVC pipe, which are offset from the main PVC > frame by 90 degree PVC "elbow" fittings. The spacing slots are separated by > .25", and are all symmetrically cut into the PVC by a circular saw with > multiple wooden spacers of identical .25" width. The 19 coil windings (of #18 > wire) are then pulled tightly to ensure optimal loop symmetry, in a system > which apparently provides excellent nulling capability. The 490 feet loop coil > of #18 stranded wire tunes from 167 kHz to 444 kHz in the current setup, > but I plan to add a few more turns to drop the coverage down to 150 kHz. > Photos of the loop and support structure are available upon request. I'd love to see anything you might have, but can wait for your article too.I know you must be busy. The split-stator cap and center-tapped loop primary winding improves loop symmetry and balance. As to the spreading of the windings, the spreaders that splay every other turn up and down in two (maybe more) sections help a lot in increasing the range of tuning. Let me know if photos of that might help exp[lain what it looks like. I used wide tongue depressors, but small round PVC pipe sections would probably work better in that big loop. Rick Kunath _______________________________________________ IRCA mailing list IRCA@hard-core-dx.com 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: irca@hard-core-dx.com **************2009 3 Free CREDIT SCORES: See Your 3 Credit Scores from All 3 Bureaus FREE! (http://pr.atwola.com/promoclk/100126575x1221797372x1201397989/aol?redir=https:%2F%2Fwww.freescore.com%2FOffers%2FStart%2FFreeCreditRepor tAndScore.aspx%3FID%3D91831F371F138345B53A153F49D4D872%26siteid%3De927580bf7 ) _______________________________________________ IRCA mailing list IRCA@hard-core-dx.com 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: irca@hard-core-dx.com