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I would be very interested in hearing the tuning recommendations for those of us haing problems on 15 with the three feedlines. Thanks. Herb - KG6OK herbr@netcom.com On Thu, 8 Jun 2000, Natan Huffman wrote: > Dear Friends, > > As there appears to be somewhat of an "urban legend" growing concerning the > tuning of the C31XR, I thought a few comments might be helpful, even though > you may find it repetitious. > > The C31XR uses a combination open and closed feed system to excite the three > bands by a single feedline. The feedline arrives at the 10 meter driver and > through a closed sleeve comprised of two wires, the energy makes it way to > the 20 meter driver. The 20 driver and the 15 meter driver form an open > sleeve to facilitate 15 meter excitation. > > Some installations have trouble getting the 15 meter resonance within the > band. We have found that this is easily corrected by bringing the two wires > of the closed sleeve in close proximity which then raises the 15 meter > resonance to within the band. This method will preserve the lengths and > geometries of the sleeves and therefore is strongly recommended over any > element length changes. The manuals of recent vintage have the following: > > _____3) The next part installs the parallel driver wires between the 10 mtr > driver feedpoints and the 20 mtr feedpoints. > _____a) Locate the two, long wires with lugs on each end. > _____b) Slip the lug from one end of each of these two wires to the 10 mtr > driver feedpoint screws. > _____c) Add a #10 flat washer, split lockwasher and a nut - leave loose at > this time. > _____d) Place a flat washer on each of the 20 mtr feedpoint screws and slip > the other end of each wire over the 20 mtr screws. > _____d1) Please be sure the wires are parallel (not crossed). > > _____d2) It is recommended these two wires be taped > together with widths of vinyl tape spaced every three inches. Do not > cross these wires. > _____e) Add the 20 mtr hairpin coil across the 20 mtr feedpoint screws. > _____f) Slip on a #10 flat washer, split lockwasher and nut. > _____g) Align the wires and matching coil, then tighten the nuts on BOTH > the 10 AND 20 mtr drivers. > _____h) Adjust the turns on the 20 mtr hairpin coil for a small space > between turns (1/8"). > > Any antenna installation is unique. Many factors affect all our antennas > including ground topography and conductivity, structure, and of course other > antennas. the presence of these objects are responsible for variations in > the "tuning" of the C31XR. > > I've written about this subject previously on the Tower Talk reflector, so > you can search the archives for more information if you like. As always, if > you have questions or comments, please just write. The E-mail volume has > been overloading me, so my response may be delayed, but it will come! > > Thanks, > > Natan W6XR > Force 12 East > Ithaca, NY > FN12sk > force12@qth.com > > > > -------------------------------------------- > Force12Talk mailing list provided as a service by Force 12 Antennas, Inc. > Force 12 Web site: http://www.qth.com/force12 > > Submissions: send to Force12Talk@qth.com > To unsubscribe: send a blank e-mail to Force12Talk-leave@qth.com > Force12Talk Message Archive: http://www.qth.com/force12/list/force12talk > For problems with the list, contact force12@qth.com > > > -------------------------------------------- Force12Talk mailing list provided as a service by Force 12 Antennas, Inc. Force 12 Web site: http://www.qth.com/force12 Submissions: send to Force12Talk@qth.com To unsubscribe: send a blank e-mail to Force12Talk-leave@qth.com Force12Talk Message Archive: http://www.qth.com/force12/list/force12talk For problems with the list, contact force12@qth.com |
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