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300ohm,

I have stacked my pair of #22 yagis in NECs geometry edit using the original file as modeled by Ramkat.

Im not sure how to model the combining, phasing, and loading now. Also do I have to duplicate the symbols from the single yagi?

Can you help me do this
 

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Also do I have to duplicate the symbols from the single yagi?
With Symbols, what will happen is when you save the nec file, the SY cards will convert to wires, no problem. (Basically Symbols are only needed for Optimization and other specialized runs , but for huge nec files that overpower the computer system, can become a real hinderance.)

After that, in Geometry Edit, select all wires and copy and paste. Then you have a duplicate antenna. Then select all wires, and move it into position. Draw another Source wire on it at the same position as on the original, same segmentation, making note of the tag number. After that, go into NEC Editor and add a duplicate EX card, exactly the same as the original, but with the new tag number. Then do your calculations.
 

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A day of discovery

After many tower climbs, I ended up taking the second 91XG out of my setup.

I tried what Lineloss suggested. First I tried a single XG (higher one) with no preamp. Then I tried combining it with the second XG with no preamp. There was no difference or maybe a slight degredation. Then I tried the second XG (lower one) with no preamp. Signals were considerably lower than the higher XG. The difference in height was 25".

I guess that 25" made enough of a difference and the lower antenna was degrading the signal when combined with the upper antenna.

I never tried 40" spacing after discovering this. The rest of the afternoon was spent returning my setup to the single XG with the 9260. Perhaps a horizontal stack would work better at my location. But I'm done fooling with this until spring.

The single XG works considerably better than the stack. I have my trouble channels 33 and 14 at approx. 70 signal strength on my 722. They still drop out occasionally unfortunately. 33 will go to 96 and then 0 and back to 70. 14 is more stable. Guess I will live with it for the winter.
 

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I guess that 25" made enough of a difference and the lower antenna was degrading the signal when combined with the upper antenna.
It could have, but what you could have tried was moving the whole stack up or down in 3 to 6 inch increments.
 

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I guess that 25" made enough of a difference and the lower antenna was degrading the signal when combined with the upper antenna.
I agree... a different signal level exposure to both antennas is not good. That kind of sucks eh! I noticed the same effect during spacing tests with my bottom antenna below the general neighborhood roof line. Although things did not work for you, this scenario should be considered by others when deciding to stack or not to stack. Maybe it would be wise to move one's existing antenna up an down and note signal strengths in both or multiple positions before purchasing antenna #2.
 

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Maybe it would be wise to move one's existing antenna up an down and note signal strengths in both or multiple positions before purchasing antenna #2.
Yep, and that, in a lot of cases, would make a bigger difference than any optimum stacking distance.
 

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300ohm,

Thanks for the help with NEC. I think im on the right track then. Last night I duplicated the yagis in Geometry edit (1077 mm vertical separation), but I joined them with a new line and source load...but now ill read you up...fun stuff!:p

I wasnt sure about the symbols, ill disregard them for now...

I did a lot of stack testing today...ill post in the other thread...
 

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300ohm,

I did all what you said, I think ;)

So I have the pair of stacked yagis with correct geometry, then I added a source (point) on the folded dipole of the second generated yagi. When I saved this geometry, it seems to have automatically added the correct EX card, with tag, for the added source..

when I run the calcs it stops me, segments & patches exceeds dimension limit, also No Nec2d.exe to use for 11000 segments....available in c:/4nec2/exe...

thanks
 

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when I run the calcs it stops me, segments & patches exceeds dimension limit, also No Nec2d.exe to use for 11000 segments....available in c:/4nec2/exe...
You need to install (copy) the Nec2dXS executable files into your 4nec2\exe\ directory.

Files are here : http://home.ict.nl/~arivoors/

under Nec2 Support Files.
 

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300ohm,

I extracted the files to my nec folder, restarted the computer, selected nec2dxs engine in settings, and reopened the file, and get the same messages (exceeded limit....)

get these errors for every wire when segment check - Error: Wire 1 (tag 2), seg-len ( (6.e-4) ) below wlen/1000 (6.e-4)
 

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Another option

I think ganged side by side has a better chance for your situation; The narrow horizontal beam width may force you to rotor a bit more, but you may just get the channel you want. Now in a pitch fork type setup you can fine tune by moving one antenna slightly lower than the other... Technically this will give you some phase adjustment in your diminishing field.

Earlier I said:

a different signal level exposure to both antennas is not good
Signal phase is also a key player here. Since the horizontal edge is not ideal... adjustment will surely benefit your problem channel in this ganged arrangement. If you do this, remember to rotor for highest signal after each time you fine tune one antenna in the vertical plane. Yes, this adjustment will change your "optimum" calculated separation, but these ideal things seem to always end up out the door... as you have just seen.

Too bad prime tweaking time is when its cold eh!

Cheers
 

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yep, no matter, even with the trial & error method, with the stacking and gagning (in same direction), or staggared, too many variables come into play and add to that if your signal is unstable to begin with (fluctuating) it becomes impossible to get a clear measure (gauge) of the impact of the experiments youre doing...
 

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Yep, typically it's just not worth all the extra time, money and stress for one channel that is borderline....

Well at least you have tried, and now you know. Good work! ;)
 

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300ohm,

heres my input file:


Code:
CM VK5DJ
CE
SY R1_P=0.030
SY R1_L=0.281
SY DP_POS=0.145
SY DP_LEN=0.277	'Tip to Tip length of Dipole
SY DP_DIA=0.050	'Diameter of rounded Dipole ends
SY D1_P=0.188
SY D1_L=0.253
SY D2_P=0.292
SY D2_L=0.251
SY D3_P=0.416
SY D3_L=0.248
SY D4_P=0.559
SY D4_L=0.246
SY D5_P=0.720
SY D5_L=0.244
SY D6_P=0.893
SY D6_L=0.242
SY D7_P=1.074
SY D7_L=0.240
SY D8_P=1.264
SY D8_L=0.238
SY D9_P=1.463
SY D9_L=0.237
SY D10_P=1.670
SY D10_L=0.235
SY D11_P=1.886
SY D11_L=0.234
SY D12_P=2.107
SY D12_L=0.233
SY D13_P=2.332
SY D13_L=0.232
SY D14_P=2.559
SY D14_L=0.231
SY Wire_Radius=0.00127
SY Refl_Radius=0.00127
SY s00_x00=R1_P
SY s00_y00=R1_L*0.5
SY s12_x00=DP_POS
SY s14_z00=0.0
SY s15_z00=DP_DIA*0.5*SIN(22.5)
SY s16_z00=DP_DIA*0.5*SIN(45)
SY s17_z00=DP_DIA*0.5*SIN(67.5)
SY s18_z00=DP_DIA*0.5
SY s14_y00=DP_LEN*0.5
SY s15_y00=(DP_LEN-DP_DIA*(1-COS(22.5)))*0.5
SY s16_y00=(DP_LEN-DP_DIA*(1-COS(45)))*0.5
SY s17_y00=(DP_LEN-DP_DIA*(1-COS(67.5)))*0.5
SY s18_y00=(DP_LEN-DP_DIA)*0.5
SY s21_x00=D1_P
SY s21_y00=D1_L*0.5
SY s22_x00=D2_P
SY s22_y00=D2_L*0.5
SY s23_x00=D3_P
SY s23_y00=D3_L*0.5
SY s24_x00=D4_P
SY s24_y00=D4_L*0.5
SY s25_x00=D5_P
SY s25_y00=D5_L*0.5
SY s26_x00=D6_P
SY s26_y00=D6_L*0.5
SY s27_x00=D7_P
SY s27_y00=D7_L*0.5
SY s28_x00=D8_P
SY s28_y00=D8_L*0.5
SY s29_x00=D9_P
SY s29_y00=D9_L*0.5
SY s30_x00=D10_P
SY s30_y00=D10_L*0.5
SY s31_x00=D11_P
SY s31_y00=D11_L*0.5
SY s32_x00=D12_P
SY s32_y00=D12_L*0.5
SY s33_x00=D13_P
SY s33_y00=D13_L*0.5
SY s34_x00=D14_P
SY s34_y00=D14_L*0.5
GW	2	17	0.145	0.1385	0	0.145	0.136597	9.567e-3	1.27e-3
GW	2	17	0.145	0.136597	9.567e-3	0.145	0.131178	0.017678	1.27e-3
GW	3	17	0.145	0.131178	0.017678	0.145	0.123067	0.023097	1.27e-3
GW	4	17	0.145	0.123067	0.023097	0.145	0.1135	0.025	1.27e-3
GW	6	17	0.145	0.1385	0	0.145	0.136597	-9.567e-3	1.27e-3
GW	6	17	0.145	0.136597	-9.567e-3	0.145	0.131178	-0.017678	1.27e-3
GW	7	17	0.145	0.131178	-0.017678	0.145	0.123067	-0.023097	1.27e-3
GW	8	17	0.145	0.123067	-0.023097	0.145	0.1135	-0.025	1.27e-3
GW	9	183	0.145	0.1135	-0.025	0.145	0	-0.025	1.27e-3
GW	10	225	0.03	0.1405	0	0.03	0	0	1.27e-3
GW	11	203	0.188	0.1265	0	0.188	0	0	1.27e-3
GW	12	201	0.292	0.1255	0	0.292	0	0	1.27e-3
GW	13	199	0.416	0.124	0	0.416	0	0	1.27e-3
GW	14	197	0.559	0.123	0	0.559	0	0	1.27e-3
GW	15	195	0.72	0.122	0	0.72	0	0	1.27e-3
GW	16	195	0.893	0.121	0	0.893	0	0	1.27e-3
GW	17	193	1.074	0.12	0	1.074	0	0	1.27e-3
GW	18	191	1.264	0.119	0	1.264	0	0	1.27e-3
GW	19	191	1.463	0.1185	0	1.463	0	0	1.27e-3
GW	20	189	1.67	0.1175	0	1.67	0	0	1.27e-3
GW	21	187	1.886	0.117	0	1.886	0	0	1.27e-3
GW	22	187	2.107	0.1165	0	2.107	0	0	1.27e-3
GW	23	187	2.332	0.116	0	2.332	0	0	1.27e-3
GW	24	185	2.559	0.1155	0	2.559	0	0	1.27e-3
GW	19	17	0.145	-0.1385	0	0.145	-0.136597	9.567e-3	1.27e-3
GW	19	17	0.145	-0.136597	9.567e-3	0.145	-0.131178	0.017678	1.27e-3
GW	20	17	0.145	-0.131178	0.017678	0.145	-0.123067	0.023097	1.27e-3
GW	21	17	0.145	-0.123067	0.023097	0.145	-0.1135	0.025	1.27e-3
GW	23	17	0.145	-0.1385	0	0.145	-0.136597	-9.567e-3	1.27e-3
GW	23	17	0.145	-0.136597	-9.567e-3	0.145	-0.131178	-0.017678	1.27e-3
GW	24	17	0.145	-0.131178	-0.017678	0.145	-0.123067	-0.023097	1.27e-3
GW	25	17	0.145	-0.123067	-0.023097	0.145	-0.1135	-0.025	1.27e-3
GW	26	183	0.145	-0.1135	-0.025	0.145	0	-0.025	1.27e-3
GW	27	225	0.03	-0.1405	0	0.03	0	0	1.27e-3
GW	28	203	0.188	-0.1265	0	0.188	0	0	1.27e-3
GW	29	201	0.292	-0.1255	0	0.292	0	0	1.27e-3
GW	30	199	0.416	-0.124	0	0.416	0	0	1.27e-3
GW	31	197	0.559	-0.123	0	0.559	0	0	1.27e-3
GW	32	195	0.72	-0.122	0	0.72	0	0	1.27e-3
GW	33	195	0.893	-0.121	0	0.893	0	0	1.27e-3
GW	34	193	1.074	-0.12	0	1.074	0	0	1.27e-3
GW	35	191	1.264	-0.119	0	1.264	0	0	1.27e-3
GW	36	191	1.463	-0.1185	0	1.463	0	0	1.27e-3
GW	37	189	1.67	-0.1175	0	1.67	0	0	1.27e-3
GW	38	187	1.886	-0.117	0	1.886	0	0	1.27e-3
GW	39	187	2.107	-0.1165	0	2.107	0	0	1.27e-3
GW	40	187	2.332	-0.116	0	2.332	0	0	1.27e-3
GW	41	185	2.559	-0.1155	0	2.559	0	0	1.27e-3
GW	100	363	0.145	0.1135	0.025	0.145	-0.1135	0.025	1.27e-3
GW	101	17	0.144955	0.1385	1.077001	0.144955	0.136597	1.086568	1.27e-3
GW	102	17	0.144955	0.136597	1.086568	0.144955	0.131178	1.094679	1.27e-3
GW	103	17	0.144955	0.131178	1.094679	0.144955	0.123067	1.100098	1.27e-3
GW	104	17	0.144955	0.123067	1.100098	0.144955	0.1135	1.102001	1.27e-3
GW	105	17	0.144955	0.1385	1.077001	0.144955	0.136597	1.067434	1.27e-3
GW	106	17	0.144955	0.136597	1.067434	0.144955	0.131178	1.059323	1.27e-3
GW	107	17	0.144955	0.131178	1.059323	0.144955	0.123067	1.053904	1.27e-3
GW	108	17	0.144955	0.123067	1.053904	0.144955	0.1135	1.052001	1.27e-3
GW	109	183	0.144955	0.1135	1.052001	0.144955	0	1.052001	1.27e-3
GW	110	225	0.029955	0.1405	1.077001	0.029955	0	1.077001	1.27e-3
GW	111	203	0.187955	0.1265	1.077001	0.187955	0	1.077001	1.27e-3
GW	112	201	0.291955	0.1255	1.077001	0.291955	0	1.077001	1.27e-3
GW	113	199	0.415955	0.124	1.077001	0.415955	0	1.077001	1.27e-3
GW	114	197	0.558955	0.123	1.077001	0.558955	0	1.077001	1.27e-3
GW	115	195	0.719955	0.122	1.077001	0.719955	0	1.077001	1.27e-3
GW	116	195	0.892955	0.121	1.077001	0.892955	0	1.077001	1.27e-3
GW	117	193	1.073955	0.12	1.077001	1.073955	0	1.077001	1.27e-3
GW	118	191	1.263955	0.119	1.077001	1.263955	0	1.077001	1.27e-3
GW	119	191	1.462955	0.1185	1.077001	1.462955	0	1.077001	1.27e-3
GW	120	189	1.669955	0.1175	1.077001	1.669955	0	1.077001	1.27e-3
GW	121	187	1.885955	0.117	1.077001	1.885955	0	1.077001	1.27e-3
GW	122	187	2.106955	0.1165	1.077001	2.106955	0	1.077001	1.27e-3
GW	123	187	2.331955	0.116	1.077001	2.331955	0	1.077001	1.27e-3
GW	124	185	2.558955	0.1155	1.077001	2.558955	0	1.077001	1.27e-3
GW	125	17	0.144955	-0.1385	1.077001	0.144955	-0.136597	1.086568	1.27e-3
GW	126	17	0.144955	-0.136597	1.086568	0.144955	-0.131178	1.094679	1.27e-3
GW	127	17	0.144955	-0.131178	1.094679	0.144955	-0.123067	1.100098	1.27e-3
GW	128	17	0.144955	-0.123067	1.100098	0.144955	-0.1135	1.102001	1.27e-3
GW	129	17	0.144955	-0.1385	1.077001	0.144955	-0.136597	1.067434	1.27e-3
GW	130	17	0.144955	-0.136597	1.067434	0.144955	-0.131178	1.059323	1.27e-3
GW	131	17	0.144955	-0.131178	1.059323	0.144955	-0.123067	1.053904	1.27e-3
GW	132	17	0.144955	-0.123067	1.053904	0.144955	-0.1135	1.052001	1.27e-3
GW	133	183	0.144955	-0.1135	1.052001	0.144955	0	1.052001	1.27e-3
GW	134	225	0.029955	-0.1405	1.077001	0.029955	0	1.077001	1.27e-3
GW	135	203	0.187955	-0.1265	1.077001	0.187955	0	1.077001	1.27e-3
GW	136	201	0.291955	-0.1255	1.077	0.291955	0	1.077001	1.27e-3
GW	137	199	0.415955	-0.124	1.077001	0.415955	0	1.077001	1.27e-3
GW	138	197	0.558955	-0.123	1.077001	0.558955	0	1.077001	1.27e-3
GW	139	195	0.719955	-0.122	1.077001	0.719955	0	1.077001	1.27e-3
GW	140	195	0.892955	-0.121	1.077001	0.892955	0	1.077001	1.27e-3
GW	141	193	1.073955	-0.12	1.077001	1.073955	0	1.077001	1.27e-3
GW	142	191	1.263955	-0.119	1.077001	1.263955	0	1.077001	1.27e-3
GW	143	191	1.462955	-0.1185	1.077001	1.462955	0	1.077001	1.27e-3
GW	144	189	1.669955	-0.1175	1.077001	1.669955	0	1.077001	1.27e-3
GW	145	187	1.885955	-0.117	1.077001	1.885955	0	1.077001	1.27e-3
GW	146	187	2.106955	-0.1165	1.077001	2.106955	0	1.077001	1.27e-3
GW	147	187	2.331955	-0.116	1.077001	2.331955	0	1.077001	1.27e-3
GW	148	185	2.558955	-0.1155	1.077001	2.558955	0	1.077001	1.27e-3
GW	149	363	0.144955	0.1135	1.102001	0.144955	-0.1135	1.102001	1.27e-3
GE	0
LD	5	0	0	0	58000000
GN	-1
EK
EX	0	100	182	0	1	0		
EX	0	149	182	0	1	0		
FR	0	10	0	0	521	0.1
RP	0	1	61	1000	90	0	3	6		
EN
 

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300ohm,

heres my input file:
Ahh, yes. You have 18,487 segments, heh. Way more than the large 11,000 segment engine allows. You need to select all wires in Geometry Edit and resegment the whole stack.
 

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300ohm,

Ok, thanks. I did redo segmentation in Geometry edit options, i set it to the min = 10. I didnt get any more warnings.


it gives a horizontal gain of 19.1 dBi at 521 Mhz, but the 3D color viewer only shows a color pattern around the lower Yagi, is this wrong?
 

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but the 3D color viewer only shows a color pattern around the lower Yagi, is this wrong?
Nothing. The 3D patterns are centered on the X,Y,Z = 0 coordinate. Make sure your AGT = 1.0 (0db) before reading the gain figures. The gain should be about 3 db above a single antenna. 2 EX cards assume perfect feed lines. In real life, youll get less.
 

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So far the stacked yagis I modeled from 1 wl up to 2 wl, with increaments of 0.2 wl, showed optimum spacing at 1.8-2 wl spacing. The higher spacings showed greatest gain, and side lobes seemed to extend forward (and upward) further than with the lower spacings...

Anyway, for all this, were talking about tenths of dBs :rolleyes:
 
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