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rerun my stacking study for the C31XR's. Short version, NEC-4 shows slightly less variance as NEC-2, but similar results. The larger spacings do increase 20m gain to a point, but have artifacts in the 15m and 10m patterns. Someone whose tower guys force the use of 30'-35' spacing should not be upset. The so-called 45-50 foot optimum is only so on one band. But you can draw your own inferences. You should view the table using a fixed font on your mail program. ================================ Antenna: Force 12 C31XR, two-stack. Dimensions: owner's manual, actual constructed dimensions Feed configuration: Separate feed configuration & 15m DE position used for simplicity. Unused DE's shorted across for each band run. Calculation Engine: NEC-4d Shell: EZNEC/4 Segment density: 1002 overall. Run freqs: 14.05, 14.175, 14.3; 21.05, 21.225, 21.4; 28.05, 28.5, 29.5 Notation: Gain-dbi@degrees elev (f/b) * not meaningful [] see notes below ================================= Runs at 95/64 over ground (31' separation) 20m 15m 10m low 15.68@12(25) 16.87@8(16) 17.39@6(20) mid 15.72@12(21) 17.10@8(14) 18.31@6(18) high 15.72@11(17) 17.25@8(12) 15.50@6(17) Runs at 95/60 over ground (35' separation) 20m 15m 10m low 15.83@12(24) 16.89@8(17) 17.37@6(22) mid 15.84@12(18) 17.24@8(18) 18.30@6(20) high 15.82@12(15) 17.49@8(13) 15.31@6(*)[1] Runs at 102/57 over ground (45' separation) 20m 15m 10m low 16.07@11(15) 16.76@8(*) [1] 17.17@6(28)[2] mid 16.05@11(13) 17.15@8(20)[1] 18.01@6(26)[2] high 16.04@11(12) 17.43@8(14) 15.19@6(*) [3] Runs at 110/55 over ground (55' separation) 20m 15m 10m low 15.84@11(13)[1] 16.47@7(*)[1,3] 16.82@5(28)[2] mid 15.96@10(15)[1] 16.81@7(18)[3] 17.66@5(22)[2] high 16.04@10(10)[1] 17.06@7(15)[3] 15.27@5(27)[2] [1] large vertical lobe [2] two large upper lobes ~12dbi@~50d,~40d [3] large upper lobe ~12dbi@~45d ===================================== ----- Original Message ----- From: "Rick Bullon" <kc5ajx@hotmail.com> To: <Force12Talk@qth.com> Sent: Monday, July 29, 2002 12:28 PM Subject: Re: [Force 12 Talk]C31XR Stacks.... Was C31XRs in SO2R ??? > Hello Guys > I don't have any of the antenna's talked about in this thread but I have > noticed that on the F-12 web page there are pictures of 2 stacks of F-12 > beams. One is the stack at VE1JF he has 2 C51XRN's with a C31XR in the > middle. Another example on the site is W9NO who has a C51XR over a C31XR. > I know the thread is about stacking C31XR's but maybe if someone asked on of > these guys how their stacks are working it would give some real world data > to the discussion. > 73 > Rick > KC5AJX > > > ----Original Message Follows---- > From: "Guy Olinger, K2AV" <k2av@contesting.com> > To: "Bob Henderson" <bob@cytanet.com.cy>,"Pete Smith" > <n4zr@contesting.com>,<Force12Talk@qth.com> > Subject: Re: [Force 12 Talk] Re: C31XRs in SO2R ??? > Date: Mon, 29 Jul 2002 11:36:47 -0400 > > I'm sorry, but I have full double antenna models for C31XR, and > 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 > > > _________________________________________________________________ > Send and receive Hotmail on your mobile device: http://mobile.msn.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 > > -------------------------------------------- Force12Talk mailing list provided as a service by Force 12 Antennas, Inc. 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