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>Kevin, > >I noticed in your post you stack a C51XR/C31XR and C3E. For practical >purposes, the C31XR and C51XR are identical, but the C3E is not. Did you >make any adjustments (such as length of coax to compensate for phase >differences) or just "brute forced" the feeding of the C3E. Stacking non >identical antennas can be challenging! Or, perhaps the C3E is not part of >the XR stack. > >We are often asked about this type of scenario but just have not had the >time to do a good analysis and develop a recommendation. There was a post within the last couple of months on Towertalk about this. If I remember the particulars correctly, this person had stacked one of your multiband antennas with the closed sleeve feed system, with a straight yagi with split dipole feed, and used NEC-2 and lots of trial and error to calculate the phase shift that was required to achieve pattern addition. The number was striking, I remember -- ~ 160 degrees. He said it then worked roughly as predicted. From some other things I've read, I'm now wondering if this analysis was good or not, since NEC-2 reportedly has trouble with modeling this type of feed. Nonetheless, a thought. 73, Pete N4ZR Don't forget to update your entry in the World Contest Station Database http://206.102.70.3/search.htm ---------------------------------- Force12Talk mailing list provided as a service by Force 12 Antennas, Inc. Force 12 Web site: http://www.qth.com/force12 To unsubscribe, send a blank e-mail to force12talk-leave@qth.com For problems with the list, contact force12@qth.com |