Canadian TV, Computing and Home Theatre Forums banner

81 - 100 of 148 Posts

·
Registered
Joined
·
20 Posts
I now have "edit" privileges of my posts, so I fixed the post above with fixed drawing and download file to add the size of the dipole element, which I missed last night.

It's 29-7/8" end to end.
 

·
Registered
Joined
·
3,396 Posts
Hi-VHF STELLAR LABS 30-2475 8-El FD-YAGI:

I uploaded 4nec2 Analysis. Triple Reflector Rods weren't all that effective at improving F/B & F/R Ratios....esp. when compared to Optimized 8-El FD-YAGI with two Additional Directors at the Front, rather than two at the Rear (better use of available Metal):
HiVHF 8-El FD-Yagi - Stellar Labs 302475

Compare to Optimized 8-El FD-Yagi:
http://imageevent.com/holl_ands/yagis/hivhf8elfdyagiopt

Here's the EVAL *.html Performance File for the Stellar Labs 8-El FD-Yagi:
E:\Antenna Modeling\4nec2 models\Band - Hi-VHF\HiVHF - Yagi\HiVHF - Yagi - 8-El FD Stellar Labs\HiVHF_Stellar-Labs_8El_FD_Yagi.nec





 

·
Registered
Joined
·
3,396 Posts
A-C Y10-7-13 10-EL FD-YAGI PLUS 2 REFL. RODS & 3 DIRECTOR RODS:

I uploaded 4nec2 Analysis for attaching 3 Director Rods re-purposed from the Front of the Stellar Labs 8-El FD-Yagi and 2-Reflector Rods from the Rear. Max Gain only improved by about 1 dB, with about 2 dB improvement on the lowest Channels, where the 4nec2 MODEL for the Y10-7-13 indicated there MIGHT be some Gain Loss.:
Hi-VHF A-C Y-10-7-13 plus 2 RRs & 3 Dirs

Note that tupelo's 4nec2 MODEL for the Original Y10-7-13 predicts significant Gain Roll-Off and SWR Rise on Ch13 (with or without 0.125-in Boom Corrections). Similar behavior was found in the "similar" Winegard YA-1713 10-El Log-Yagi...which I PROVED was NOT happening in the Actual Antenna. Hence I suspect that the 4nec2 MODEL for the Y10-7-13 MAY NOT be accurate on Ch13 (or Ch7). [Thus far, this is frustrating my attempts to do Optimization Runs.....]

Here's the EVAL *.html Performance File:
E:\Antenna Modeling\4nec2 models\Band - Hi-VHF\HiVHF - LogYagi+DualDriven\HiVHF - A-C Y10-7-13 + 3 DirRods + 2 ReflRods\A-C_Y10-7-13+2ReflRods+3DirRods.nec





 

·
Registered
Joined
·
3,396 Posts
If higher Gain is desired, note that at least one more Director and perhaps the ENTIRE Stellar Labs Antenna (4 Directors with Folded Dipole and all 3 Reflector Rods removed) can be attached to the Front of the Y10-7-13.....I'll do some 4nec2 runs....

Since the Y10-7-13 MODEL isn't very well behaved, I also believe that it would be interesting to flip it around and attach the Front Boom from the Y10-7-13 to the Existing Stellar Labs 8-El FD-Yagi....stand by for some 4nec2 runs....which will be SIMPLE to also run through the Optimizer.
 

·
Registered
Joined
·
20 Posts
Since the Y10-7-13 MODEL isn't very well behaved, I also believe that it would be interesting to flip it around and attach the Front Boom from the Y10-7-13 to the Existing Stellar Labs 8-El FD-Yagi
THAT'S an interesting supposition, and I didn't think of that one!

I'm working on changing my antenna mast over to a swivel mount (bottom of the mast will then stay attached, but allow mast to swing down to my front porch roof), so I can more easily drop it for making changes with OUT the possibility of me falling 25' and getting seriously hurt. Right now making changes consists of me standing on my roof, undoing 3 U-bolts strapping the mast to a 22' pole, and then lifting the entire antenna mast AND antennas up and out. Then lowering the whole mess to lay on my roof. That's while holding about 1' of the end of the mast (that's 10' long) almost over my head, and trying to keep it balanced so it doesn't start flopping over. We all know what happens once it reaches a certain angle.

I'm not getting younger, and I'm not as strong as I used to be.

Thanks Holl_ands!
 

·
Registered
Joined
·
3,396 Posts
For some reason, the EVAL *.html file for Hi-VHF A-C Y-10-7-13 plus 2 RRs & 3 Dirs doesn't display the 3D MODEL....I did a quick look, but need to keep looking for the problem in the underlying 4nec2 File....

UPDATE: NOW IT'S WORKING....BE SURE RE-DOWNLOAD LATEST 4nec2 FILE....
 

·
Registered
Joined
·
20 Posts
If higher Gain is desired, note that at least one more Director and perhaps the ENTIRE Stellar Labs Antenna (4 Directors with Folded Dipole and all 3 Reflector Rods removed) can be attached to the Front of the Y10-7-13.....I'll do some 4nec2 runs....

Since the Y10-7-13 MODEL isn't very well behaved, I also believe that it would be interesting to flip it around and attach the Front Boom from the Y10-7-13 to the Existing Stellar Labs 8-El FD-Yagi....stand by for some 4nec2 runs....which will be SIMPLE to also run through the Optimizer.
Holl_ands, did you have a chance to run those extra runs? Maybe I missed them somewhere?
 

·
Registered
Joined
·
3,396 Posts
SQUIRREL!!!!! I got distracted by an alleged Ch2-69 Omni-Directional Crossed Loop Antenna....NOT...unless you stack TWO different sized Loops and drive EACH of them with a 2-Port 90-degree Quadrature Hybrid....

Your's is next on my list....
 

·
Registered
Joined
·
3,396 Posts
SQUIRREL...AGAIN....although I have "most" Antenna Files backed up on my Laptop, a few weeks ago my External 2x500MB NAS RAID Drive (Dual Redundant storage for EVERYTHING) suffered a failure to the Power Supply or Controller. So for about a week now I've been trying to Recover one or the other *.EXT3 (Linux) SATA drives to one of my spare Desktop drives in Win readable NTFS format. I tried a couple of my (IT Expert) son's Recovery CD's and OpenSUSE (Linux OS, which did NOT see ANY the OS Drives & I'm NOT a Linux expert). I finally ran across DiskInternals Viewer Utility that runs under VISTA64 to Recover *EXT2/3/4 drives to another NTSF formatted drive or partition. So after another 4.5-hours, I can now access a Shared Folder from either Computer....but it keeps "disappearing" after awhile....hmmmm.

Long term plan is to implement a Dual Redundant SDD RAID Array (Solid State Drive has no moving parts).

I also took the time to replace one of the 3 Case Fans in the Desktop and vacuum out the dust in both computers...cuz right NOW my Temp Gauge sez it's 103.1 DegF on my front porch....and my wife doesn't like what A/C does to her sinuses. At some time in the future I'll have to pull the Heatsink/Fan Assy out of the Overclocked Desktop and "dip" JUST the Alum. Cooling Fins in some sort of cleaner and reattach with a new dollop of Heatsink Compound....but for the next couple days, I'm only running it to TRY keeping the Shared Drive accessible.
 

·
Registered
Joined
·
3,396 Posts
Turns out adding 4 Directors from Front Boom of Y10-7-13 to the Stellar 8-El Yagi is NOT better than adding 3 Directors from Front Boom of Stellar 8-El Yagi to the Y10-7-13.....so I'm only going to post the SUMMARY Results, rather than the full Analysis.

I didn't know exactly what the Separation Distance would be at the JOINT between the FRONT Element on the Stellar Yagi and the REAR Element on the Y10-7-13's Front Boom Extension, so I simply made it an OPTIMIZATION Variable in the 4nec2 Model. [In third run, for sure it would require cutting off some of the boom stub....in second run it would be CLOSE to no-Mod Separation....but I don't know exactly what that number is on the Real Antennas.]

First Run assumed no other mods, but resulted in SEVERE Loss across Ch13 (WHAT'S UP WITH Ch13 on these Dual-Drive and Log-Yagi Antennas???).

Second Run allowed the Optimizer to investigate Shortening (Trimming) the Lengths of the four NEW Directors as well as the Joint Separation....this is what is shown below.

Third Run allowed same Optimization as above, but ALSO allowed the four New Directors to be RELOCATED along the Length of the Boom. This resulted in only a 0.4 dB improvement on nearly all but Ch13, where it resulted in it being 0.8 dB LOWER on the 216 MHz upper part of Ch13.

EVAL SUMMARY for Y10-7-13 PLUS 2 Reflector Rods & 3 Directors from Front Boom of Stellar 8-El Yagi:
Code:
Input file : A-C_Y10-7-13+2ReflRods+3DirRods.nec
Freq sweeps: [(174, 1.5, 29)]
Autosegmentation: NO

         --- Gain ---              -- Ratios -- -- Impedance --
   Freq    Raw    Net   SWR BeamW    F/R    F/B    Real    Imag  AGT  corr
==========================================================================
  174.0  10.40  10.23  1.49  50.4  12.43  12.43  207.08   35.20 0.96 -0.16
  175.5  10.20  10.10  1.36  50.6  12.02  12.02  227.65   35.11 0.96 -0.16
  177.0   9.75   9.75  1.05  50.4  10.72  10.72  292.31   13.27 0.96 -0.16
  178.5  12.87  12.28  2.11  41.5  17.57  17.57  165.03 -102.65 0.96 -0.16
  180.0  12.23  11.76  1.94  43.5  19.17  19.65  156.33  -26.34 1.00  0.01
  181.5  11.98  11.58  1.84  43.9  19.04  19.59  162.95   -8.65 1.00  0.01
  183.0  11.96  11.57  1.82  43.6  19.51  20.54  165.18    0.78 1.00  0.01
  184.5  12.03  11.65  1.81  43.2  20.21  22.37  165.69    9.35 1.00  0.01
  186.0  12.16  11.78  1.82  42.6  21.02  25.47  166.14   18.97 1.00  0.02
  187.5  12.33  11.95  1.81  42.0  21.88  31.40  167.80   30.25 1.00  0.02
  189.0  12.54  12.17  1.80  41.4  22.65  40.29  171.86   43.29 1.00  0.02
  190.5  12.77  12.43  1.76  40.7  23.71  28.28  179.66   57.72 1.00  0.02
  192.0  13.02  12.72  1.70  40.0  22.81  22.81  192.82   72.50 1.00  0.01
  193.5  13.25  13.00  1.61  38.9  19.44  19.44  213.01   85.26 1.00  0.01
  195.0  13.45  13.28  1.49  37.9  17.10  17.10  240.94   91.31 1.00  0.01
  196.5  13.60  13.50  1.36  37.0  15.43  15.43  273.13   83.60 1.00  0.01
  198.0  13.70  13.65  1.21  36.0  14.29  14.29  297.62   57.74 1.00  0.01
  199.5  13.76  13.75  1.08  35.1  13.66  13.66  298.44   23.42 1.00  0.01
  201.0  13.80  13.79  1.10  34.2  13.58  13.58  274.19    3.92 1.00  0.01
  202.5  13.85  13.79  1.24  33.5  14.22  14.22  242.73   15.08 1.00  0.01
  204.0  13.91  13.77  1.44  32.7  16.01  16.01  224.88   58.85 1.00  0.02
  205.5  13.88  13.58  1.71  31.9  19.01  20.11  244.23  135.48 1.00  0.02
  207.0  13.46  12.91  2.05  31.1  17.65  24.17  366.35  234.39 1.00  0.02
  208.5  12.30  11.52  2.37  30.2  15.23  15.23  695.18   94.57 1.00  0.02
  210.0  10.65   9.78  2.49  28.9   9.49   9.49  452.94 -312.21 1.01  0.05
  211.5   9.63   8.77  2.47  28.8   6.57   6.57  168.98 -165.32 1.01  0.05
  213.0   9.95   7.78  4.37  35.8   8.07   8.07   88.52  155.73 1.01  0.05
  214.5   3.32   0.04  6.36  49.1   5.81  10.68 1073.16  925.64 1.01  0.05
  216.0  -1.83  -4.51  5.23  49.8  -1.10  -1.10  634.97 -734.52 1.01  0.05
Press any key to continue . . .

EVAL SUMMARY for Stellar 8-El Yagi with 2 Extra Reflector Rods PLUS 4 Directors from Front Boom of Y10-7-13:
Code:
Input file : C:\Python32\HiVHF_Stellar-Labs_8El_FD_Yagi+4DirsTrimYA.nec
Freq sweeps: [(174, 1.5, 29)]
Autosegmentation: NO

         --- Gain ---              -- Ratios -- -- Impedance --
   Freq    Raw    Net   SWR BeamW    F/R    F/B    Real    Imag  AGT  corr
==========================================================================
  174.0   9.53   8.10  3.25  54.6  13.15  13.15   99.94  -81.93 1.00 -0.01
  175.5   9.59   8.35  2.98  54.4  14.15  14.15  105.80  -63.94 1.00 -0.01
  177.0   9.67   8.58  2.77  54.0  15.08  15.08  111.27  -46.14 1.00 -0.01
  178.5   9.76   8.80  2.60  53.5  15.86  15.86  116.63  -28.43 1.00 -0.01
  180.0   9.85   8.99  2.46  53.1  16.40  16.40  122.07  -10.73 1.00 -0.01
  181.5   9.95   9.18  2.35  52.6  16.65  16.65  127.75    7.04 1.00 -0.01
  183.0  10.04   9.33  2.26  52.2  16.60  16.60  133.84   24.96 1.00 -0.01
  184.5  10.14   9.48  2.19  51.7  16.32  16.32  140.51   43.06 1.00 -0.01
  186.0  10.23   9.62  2.14  51.3  15.89  15.89  147.98   61.36 1.00 -0.00
  187.5  10.33   9.75  2.10  50.8  15.39  15.39  156.46   79.81 1.00 -0.00
  189.0  10.43   9.87  2.07  50.3  14.88  14.88  166.21   98.35 1.00 -0.00
  190.5  10.52   9.98  2.05  49.7  14.40  14.40  177.47  116.79 1.00 -0.00
  192.0  10.61  10.08  2.04  49.0  13.98  13.98  190.53  134.89 1.00 -0.00
  193.5  10.69  10.16  2.03  48.3  13.63  13.63  205.61  152.24 1.00 -0.00
  195.0  10.77  10.25  2.02  47.6  13.38  13.38  222.88  168.31 1.00 -0.00
  196.5  10.84  10.33  2.00  46.9  13.21  13.21  242.34  182.39 1.00 -0.00
  198.0  10.90  10.40  1.99  46.2  13.16  13.16  263.71  193.65 1.00 -0.00
  199.5  10.96  10.48  1.96  45.4  13.22  13.22  286.34  201.24 1.00 -0.00
  201.0  11.02  10.56  1.94  44.7  13.42  13.42  309.11  204.48 1.00 -0.00
  202.5  11.07  10.63  1.90  44.0  13.76  13.76  330.46  203.22 1.00 -0.00
  204.0  11.13  10.72  1.86  43.3  14.29  14.29  348.70  198.03 1.00 -0.00
  205.5  11.18  10.80  1.82  42.6  15.04  15.04  362.50  190.41 1.00 -0.00
  207.0  11.24  10.88  1.78  41.9  15.73  16.06  371.38  182.48 1.00 -0.00
  208.5  11.31  10.97  1.76  41.0  15.74  17.47  376.17  176.34 1.00 -0.00
  210.0  11.37  11.04  1.75  40.3  15.57  19.38  378.81  173.34 1.00 -0.00
  211.5  11.41  11.08  1.75  39.3  15.37  22.00  381.93  173.34 1.00 -0.00
  213.0  11.42  11.08  1.76  38.1  15.15  25.40  387.88  174.13 1.00 -0.00
  214.5  11.36  11.02  1.76  36.9  14.82  27.57  397.16  171.18 1.00 -0.00
  216.0  11.20  10.89  1.72  35.6  14.48  25.32  405.50  158.70 1.00 -0.00
Press any key to continue . . .
 

·
Registered
Joined
·
20 Posts
Thanks! Up to 2db~ extra gain is worth going after.

It looks like it might be worth trying this, so it appears it'll be adding the directors from the Stellar onto the front of the Y10-7-13 as the best way to go.

I was going to install the higher mast this weekend to get my antennas 10+ feet higher, but it's been raining since late last night, and everything is soaking wet. I'm not going on the roof until it's dry again. So, probably a few more days for sure.
 

·
Premium Member
Joined
·
1,127 Posts
holl_ands:

I see 5 directors for the MCM 30-2475 in MikeBear's drawing and photos, but only 4 directors in your model. One is very close to the DE. Am I looking at it wrong?
 

·
Registered
Joined
·
4,935 Posts
Rabbit, you are correct. I looked at the photo of mine installed on my chimney,
indeed there are 5 directors, not 4.
I edited holl_ands' file in a text editor and published the new eval using nikiml's python scripts.
Noted improved gain, vswr & front/rear ratio with that edit.

stellar_30-2475.nec

I also scanned to pdf on the flatbed scanner, the instruction sheets that came with it. It has a rough gain chart on it
that the instruction sheet from MCM website does not. Might be useful. Their own specs call it out as an 8 el yagi,
seems they can't count. So not sure we can count on their gain plot either:)
http://antennafiles.linuxx.org/~mrf/necfiles/stellarlabs_30-2475.pdf

holl_ands,
When you have a chance, have a look and see if it requires any further edits?
 

·
Premium Member
Joined
·
1,127 Posts

·
Registered
Joined
·
4,935 Posts

·
Registered
Joined
·
3,396 Posts
It is ALSO possible (and I think LIKELY) that the FIRST MISTAKE was installing the Front Boom BACKWARDS (leaving the front w/o ANY Director...which led to the SECOND MISTAKE of attaching one of the REAR Reflectors to the Front)....so all of the Element-to-Element Spacings would be ALL DIFFERENT, not just a swap of two Elements.

The OP should take down the Antenna and follow the detailed Dimensions in Mike Bear's Annotated Drawing (see two posts back)....
 

·
Registered
Joined
·
4,935 Posts
good point,when I put mine together, I made sure the mast mount was at the center of gravity...
 

·
Registered
Joined
·
4,935 Posts
Here's a picture of mine... Looks like I have them two upper & lower rear reflector elements in the back instead of in the front.
Need to flip that one vertical section in the rear around 180 degrees. Have to admit, them instructions were pretty worthless.
Get what ya pay for I guess.
 

·
Registered
Joined
·
3,396 Posts
I don't think it's going to make much of a difference....but I'll do some 4nec2 runs, incl. sliding the Upper/Lower Pair FORWARD, more like a Corner Reflector, plus a couple more Reflector Rods....and deleting RR's to increase Gain to Rear. I also plan to do some runs to find the OPTIMUM solution(s)...just for drill...and comparisons....

Note that there was a ERROR in my Analysis of the Stella Labs 8-El FD Yagi....for some mysterious reason I can't begin to fathom, I inadvertently left out the Element [hidden] just 2.5-in in front of the Active Folded Dipole, so it's really a 9-El FD Yagi....but only negligible Gain differences and SWR is significantly reduced to Under 2.2:
http://imageevent.com/holl_ands/yagis/hivhf9elfdyagistellarlabs

See similar discussion here:
Carlsbad, San Diego: Older 8 bay bowtie, no signal? - Page 2 - AVS Forum | Home Theater Discussions And Reviews
 
81 - 100 of 148 Posts
Top