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spacing beyond 31' or so does not serve 10 or 15. It improves 20, but at the expense of the other two. One has to pick the band you want best optimized, as may be suspected. I am not in agreement with the purported F12 figures. Using TA does not give correct results because all it does is combine two free-space patterns, and does not account for interactions. There is significant near field interaction between two stacked C31's that has to be accounted for by modeling the entire stack together. Pete, I have an EZNEC 3 C31XR stack model if you want to run it and play around with it. 7 ----- Original Message ----- From: "Bob Henderson" <bob@cytanet.com.cy> To: "Pete Smith" <n4zr@contesting.com>; <Force12Talk@qth.com> Sent: Monday, July 29, 2002 9:52 AM Subject: Re: [Force 12 Talk] Re: C31XRs in SO2R ??? > Pete > > Thanks for the input. I suspect you are right about the spacing. If you > have the time/means to do some modelling that would be just great. I'd > certainly appreciate the help. > > 73 > > Bob 5B4AGN, P3F, ZC4ZM > > > ----- Original Message ----- > From: "Pete Smith" <n4zr@contesting.com> > To: "Bob Henderson" <bob@cytanet.com.cy> > Sent: Monday, July 29, 2002 1:30 PM > Subject: Re: [Force 12 Talk] Re: C31XRs in SO2R ??? > > > > At 10:41 AM 7/29/02 +0000, you wrote: > > >I am thinking of around 30ft, 60ft & 90ft for mine with a Magnum 340N at > > >120ft. I'd be interested to know your plans. > > > > Bob, for what it's worth (free advice is worth what it costs), I think > that > > spacing is a bit close. Given that tribander stack spacing is a > > compromise, the compromise for the next few years wants to emphasize 20 > and > > 15, not 15 and 10. Without actually modeling it I couldn't be sure, but > my > > hunch is that you want more on the order of 35 feet, maybe more. The N > > yagi is said to be just fine quite close to Force 12 tribanders, so I > would > > think 35/70/105/120 would be excellent. > > > > If you like, I have some modeling tools that would let me do a more > careful > > evaluation of the stack, at least. It sounds like it would be fun to do. > > > > > > 73, Pete N4ZR > > > > Check out the World HF > > Contest Station Database at > > www.pvrc.org > > > > > > > > > > > > > > > -------------------------------------------- > Force12Talk mailing list provided as a service by Force 12 Antennas, Inc. > Force12 Web Site: http://www.force12inc.com > > To Submit Message to the List: Force12Talk@qth.com > To unsubscribe and view the Message Archive: see http://qth.com/force12/list > For problems with the list: contact n4zr@qth.com > > -------------------------------------------- Force12Talk mailing list provided as a service by Force 12 Antennas, Inc. Force12 Web Site: http://www.force12inc.com To Submit Message to the List: Force12Talk@qth.com To unsubscribe and view the Message Archive: see http://qth.com/force12/list For problems with the list: contact n4zr@qth.com |