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Subject: C31XR Stacks
Author: Jack Brabham KZ5A <kz5a@mindspring.com>
Date: 31-Jul-2002 09:57:03
All,

This has been a very interesting and informative thread. I currently have
C31@75 , C31@120 , and Mag240N@135. I'm currently researching the best
way to add a third C31 or a C49 to the stack and also the potential of
converting the C31s to split feed SO2R. The SO2R part sounds like a
workable idea. The tower is currently 120 ft and could be extended to160 ft
before running out of guy radius.

One of the questions I'm still struggling with is if the investment in
extending the tower is really worth while. I operate both domestic and DX
contests and chase DX between contests. The current 75/120 ft stack works
very well on DX but I'm thinking is probably to high for domestic work like
the SS.

I have done some modeling with YT and NEC4WIN. One thing I hadn't realized
was that NEC2 models of the F12 antennas are available. I've been working
with generic monobander models in NEC. How does one acquire the models?
Do I need to talk to F12 or could someone send them to me? Would be
looking for C31, C49, and M240N if available.

Thanks to all

73 Jack KZ5A


----- Original Message -----
From: "WD4K" <WD4K_1@Bellsouth.net>
To: "Guy Olinger, K2AV" <k2av@contesting.com>; <Force12Talk@qth.com>
Sent: Tuesday, July 30, 2002 7:58 AM
Subject: RE: [Force 12 Talk]C31XR Stacks


> Gotta go this morning but someone asked me about my spacing so here it is
> quickly....
> C31@35, C31@75, Mag 340N at 110, C31@117, 180B@ 124. --abt 40' spacing.
> Tommy WD4K
>
> -----Original Message-----
> From: Guy Olinger, K2AV [mailto:k2av@contesting.com]
> Sent: Monday, July 29, 2002 9:16 PM
> To: Force12Talk@qth.com
> Subject: Re: [Force 12 Talk]C31XR Stacks
>
>
> With the arrival of the EZNEC/4 program, I decided to take the time to
> 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
>
> =====================================




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This Thread
  Date   Author  
31-Jul-2002 olinger@bellsouth.net
* 31-Jul-2002 Jack Brabham KZ5A
30-Jul-2002 WD4K
29-Jul-2002 Guy Olinger, K2AV
This Author (Jul-2002)
  Subject   Date  
* C31XR Stacks 31-Jul-2002
C31XRs in SO2R ??? 27-Jul-2002