New antenna from Sirio Gain-Master

[CDX-007]

007, you're reporting to us that the SGM shows stronger signals than your modified P500? "WOW!!!" hearing that is amazing. What's different now compared to a while back when you first got your SGM?

- I first erected the SGM on the 2nd mast, replacing the IMAX, 18' from the P500.
It was evidently interacting with the P500 much more than did the IMAX.
This last test was done with all other masts / antennas down, and the base of the SGM was at 40' above ground, as was the base of the P500 before it, also with no other antennas up.

How are you getting db measurements?

Using the analog meter on my Icom IC-751A, Phil went from 8dB over 9 to 13 over in the 40 minutes it took to erect the SGM in place of the P500. Phil's S-9 + 8db has been consistent on the P500 for months. He is 10 miles from me according to Google Earth.

How did your test stations report in db's?

Same scenario, except Phil is using a Pro3.

How many stations have you compared for your report?

So far just Phil's, but in the last day I have had comments wondering 'what I did', ...my signal "sounds strong", "conditions must be good"' and so on. And I've seen what I would have to average as about the expected 2-3dB receive gain in multiple directions and distances over the P500, the 5dB I saw on Phil is the only real 'changing nothing except the antenna' test I've done and that was just to satisfy myself that it is still performing decently, even with the smashed coax, [but now I want to know what one will do if it hasn't been crushed!]

Were your comparison results from your P500 also at 120 watts?

All things were left identical on both ends, so yes.

You question the db difference between TX/RX, don't you think that the amp has something significant to add to your TX?
How would that add to your RX using an amp, turn on the pre-amp? What if you were running 10,000 watts? ?

There was never an amp in line, only the 120w iCOM IC-751a.

Why do you use an amp in such tests?

N/A

 

[dxswe]

Hallo again
I have only use 100mW tx-power to my local friend.
He is about 10 miles crowflies from me.And he gave
me S4 on his president jackson 2.
When I have antron 99 with same tx-power
he could hardly copy me.So I think the SGM is very good
antenna..

 

[Marconi]

007, thanks for the details. I'm trying to plan on how best to make my comparison test and your details help. I also hope to get similar details from Shockwave and others.

Your comparing with the Penetrator and the Imax seems fairly straight forward, since all the antennas are about the same height. But IMO the real feed point in the GM, being near the middle, might allow the GM to show and advantage in signal when the mounting brackets are equal height. That is sort'a what I was getting at, looking for opinions, in my thread on "Comparing Signals."

Here is my comparison results with the GM about 11 feet higher than my Top One. I took these reports over three mornings at times when the conditions were nice and quiet. I used my Galaxy 2547, also with an analog meter.

View attachment GM 55' vs, AP 44' .pdf

Yesterday, I set the Gain Master down with the mount about 23.5' high and the tip about 45' feet, the same as the Top One. So, if conditions permit over the next couple of days, I'll do another report on the same stations if I can catch them on the air. Then I'll have something to compare with the very bottom (the mounts) of both antennas at about the same height. I haven't recorded any signal reports yet, but I can tell already that the GM is way down compared to when it was at 55' to the tip. The AP seems to be showing 1-2 Sunits better signal already with the tips at the same height. Considering this, I probably wouldn't get signals anywhere near what Shockwave got assuming he mounted his Sigma4 vs. the GM on the same pole with the Sigma4 maybe 7' higher than the GM.

BTW, I may have already posted that I set the GM vs. my Top One with both antennas center in about the middle of each antenna. The signals were about the same from each. In this configuration I just lowered the GM 6' from being 11' higher than the Top One to 5' above the top of the Top One. For me this more or less confirms that the Top One and the GM are producing a very similar dipole type pattern. The Gain Master remains noticeably quieter at all heights and that is a big advantage.

OO7, I measured my poles and they are 35' apart and the antennas don't show any obvious signs of reaction, even though they're too close to be sure.

 

[CDX-007]

Hallo again
I have only use 100mW tx-power to my local friend.
He is about 10 miles crowflies from me.And he gave
me S4 on his president jackson 2.
When I have antron 99 with same tx-power
he could hardly copy me.So I think the SGM is very good
antenna..

Wow, that's quite a large difference!

How high were the two antennas mounted above ground, and is there anything such as a TV antenna or large tree in the near field?

What coax type have you?

 

[Shockwave]

Remember the Antron is a simple half wave that would normally have unity gain. The old claim of over 9 dbi would be accurate if they changed it to 0 dbd! Being that it's end fed with a matching network it probably has less then unity gain. Beating an Antron with the GM is no major accomplishment. Beating a Penetrator or equaling a Sigma from a fiberglass stick is a major accomplishment.

 

[CDX-007]

007, thanks for the details. I'm trying to plan on how best to make my comparison test and your details help. I also hope to get similar details from Shockwave and others.

Terrific, and as long as you insure against anything near or beneath the SGM, or even uninsulated metal guy wire, you should have a fair test.
I should add here that I have the SGM installed with the nearest set of metal guy wires about 7' below it and I will feel better when it has dacron/kevlar guy lines since it's a balanced antenna and should not have anything metallic within a ½ wave beneath it to derive all the benefit of the flat-TOA balanced design, that is to the best of my understanding.

Your comparing with the Penetrator and the Imax seems fairly straight forward, since all the antennas are about the same height. But IMO the real feed point in the GM, being near the middle, might allow the GM to show and advantage in signal when the mounting brackets are equal height. That is sort'a what I was getting at, looking for opinions, in my thread on "Comparing Signals."

Actually, both the IMAX & SGM were mounted at 45', about 5' higher than the P500, and once the SGM was placed on the P500 mast I made sure it was the same lower height as was the P500.

Here is my comparison results with the GM about 11 feet higher than my Top One. I took these reports over three mornings at times when the conditions were nice and quiet. I used my Galaxy 2547, also with an analog meter.

View attachment 3852

Interesting results which mimic mine before I removed all other surrounding antennas from the SGM's near field. That's a nice worksheet, I need to make up one of those!

How close is the Top One to the SGM? I presume the 33.5'/45' is their respective base height?

Are you using metallic guy line and if so, how far beneath the SGM?

Yesterday, I set the Gain Master down with the mount about 23.5' high and the tip about 45' feet, the same as the Top One. So, if conditions permit over the next couple of days, I'll do another report on the same stations if I can catch them on the air. Then I'll have something to compare with the very bottom (the mounts) of both antennas at about the same height. I haven't recorded any signal reports yet, but I can tell already that the GM is way down compared to when it was at 55' to the tip. The AP seems to be showing 1-2 Sunits better signal already with the tips at the same height. Considering this, I probably wouldn't get signals anywhere near what Shockwave got assuming he mounted his Sigma4 vs. the GM on the same pole with the Sigma4 maybe 7' higher than the GM.

Will you be able to lower the AP/Top One completely out of the picture to test the SGM in the wide open near field as I did when I finally saw improvement?

BTW, I may have already posted that I set the GM vs. my Top One with both antennas center in about the middle of each antenna. The signals were about the same from each. In this configuration I just lowered the GM 6' from being 11' higher than the Top One to 5' above the top of the Top One. For me this more or less confirms that the Top One and the GM are producing a very similar dipole type pattern. The Gain Master remains noticeably quieter at all heights and that is a big advantage.

Interesting about the quieting, I presume this could be due to less receive performance since the AP/Top One may be interacting with the SGM as was my P500.

OO7, I measured my poles and they are 35' apart and the antennas don't show any obvious signs of reaction, even though they're too close to be sure.

Hmmm, at 35' (basically a full wavelength) I wouldn't expect much interaction either. Will you be able to try the SGM 'Alone in your Sky'?

Oh, I should also mention that when I was getting degraded performance from the SGM due to the P500 in the near field, I still showed a flat SWR.

What coax & length to each?

 

[Shockwave]

Don't be too quick to assume minimal interaction between antennas spaced 1 wavelength apart. This happens to be one of the ideal spacing distances when you want two antennas to work as one. To confirm a parasitic interaction, one day I mounted a VHF antenna and took another with no coax and walked it in a circle around the antenna under test at 1 wavelength distance. It absolutely produced nulls and peaks in gain on the antenna under test.

 

[CDX-007]

Don't be too quick to assume minimal interaction between antennas spaced 1 wavelength apart. This happens to be one of the ideal spacing distances when you want two antennas to work as one. To confirm a parasitic interaction, one day I mounted a VHF antenna and took another with no coax and walked it in a circle around the antenna under test at 1 wavelength distance. It absolutely produced nulls and peaks in gain on the antenna under test.

GOOD TO KNOW~!

Have you guys seen this post from a couple years ago?

A fairly efficiently matched 1/2 wave with such an elevated mount should provide gain over a 3/8 wave (amount of a 5/8 left active) especially when considering it has a built-in 9' mast.

Shock, I wonder if you would actually see gain over the SigmaIV/Vector4000 if you were to mount the top of the SGM as high as is the top of the SigmaIV/Vector4k?

 

[Marconi]

007, I don't have metal guy wires, I use 3/8" double braided polyester Antenna Rope that is not supposed to stretch. I've never had one break or slip a knot.

I use two 40' pushup poles that have lost a few inches on the one supporting the AP and a couple of feet on the pole with the GM. Neither of the poles are pushed all the way out. I measure the AP at a tad over 40' to the hub with an 8' foot mast installed. This 8' foot mast is inside the hoop and attaches to top of the PU pole, so I note the antenna is 44' to the tip. While making my signal report I measured the Gain Master at 55' to the tip. All of my test with the GM had the base well over 18' above ground. Below 17' is below the peak of my roof.

Somewhere today I recounted in a post how lowering my SGM down to 50' feet affected the results compared to my AP. That was when I saw equal signals on both. And when I lowered it another 6' so the tips of the two antennas were the same height, the AP showed better signals. I have not seen such affects in such a short range of height changes before while comparing my AstroPlane to other antennas, so I'm guessing the GM is more sensitive to height, length of feed line, or something in the area affecting its performance. This might be similar to what you saw with your's earlier.

Yes, as soon as I get some more reports with the two at the same tip height, I'll remove the AP. I want to change the mounts around and compare these two again to check for location differences. I've done this before, but never saw any differences that stood out. I'll check the GM by itself while it is down. Then, if I still have some energy and the weather doesn't get too bad, I'll mount another antenna in place of the AP. So yes, I'm curious, even with the GM above my home about 10' feet or more...if getting it out back in the clear will make a difference like you suggest. That choke at the bottom may be super sensitive, because when I model a 5/8 wave center fed vertical dipole and attach a mast, the pattern went to hell in a hand basket. I didn't model the choke, so this idea is just for conversation.

I measured the distance between push-up poles today and they are 35' feet apart exactly, no big steps this time although I got 7 x 5 before. I was a very good Boy Scout in my day.

I noticed the quieting right away, and when I saw better signals to boot, I was sure that was not in the form of any loss...as you suggest. This really great antenna is just plane quiet, compared to my AP. For years I have claimed my SD'r and AP were the quietest antennas I had...other than maybe a 4 element yagi antenna I had up for about 10 years or more.

You're not seeing the GM quieter that your other antennas?

Sometimes when it is really noisy I can't perceive this difference however. The quieter it is the more I notice how quiet the GM is, and when I can read those voices in the distance without a signal, I'm impressed. I know it is hard to really tell this quiet thing while switching antennas like you do, even in 40 minutes.

Around here, conditions can be like night and day. When I switch antennas and I see the meter go down and I hear less hiss or static, that seems important to me and I don't really care if I have lost or gained hearing to get quietness, as long as I can copy stations that were in the noise before switching. You can't appreciate that...switching your antennas like you do, no mater how fast you are. You also can't tell stuff like clarity of audio and volume for the same reasons.

Both antennas have 56' foot RG8/u coax from Cable Xperts that are cut pretty close to 4 x 1/2 wave multiples at 27.205, and they both show 77% velocity factor tested on my Autek VA1 analyzer.

 

[Marconi]

GOOD TO KNOW~!

Have you guys seen this post from a couple years ago?

A fairly efficiently matched 1/2 wave with such an elevated mount should provide gain over a 3/8 wave (amount of a 5/8 left active) especially when considering it has a built-in 9' mast.

Shock, I wonder if you would actually see gain over the SigmaIV/Vector4000 if you were to mount the top of the SGM as high as is the top of the SigmaIV/Vector4k?

Scott, discussions like your link is why I made the post about Comparing Antennas. Can you imagine this guy even considering to compare a Vector to a AstroPlane on the same height mast and calling it a fair test with the Vector about 25' taller and most of the AP hanging down below the top of the mast?

007, check this recent post made by Shockwave today. I was wrong about SW mounting his Vector and the GM on the same pole at the same height to the mounting brackets.

I don't get his explaination that supports putting the two antennas at the same height to the tips, but maybe I'm reading this wrong.

When SW made his inital report a while back I assumed the taller Vector was higher at the tip than the GM and I thought his report that the GM showed about the same signals was not what I see doing a similar comparison. All of my similar comparisons show the longer antenna always doing better when higher than the other antenna and if the antennas are the same tip height the shorter antenna always shows better signals. This leads me to believe that the feed point is critical to height when comparing antennas.

I just thought I would mention that my GM was mounted at about the same tip height as my Vector was. The Vector was mounted on a 15 foot pole on my chimney with about 5 feet of mast attached with four chimney straps. I noticed the top U-bolt was tightened to the point where it kinked the mast. Out came the hack saw and I chopped off the bottom 5 feet before installing the GM. I still can't tell the antennas apart other then reduced power handling and added bandwidth. In all fairness, my chimney is over 40 feet above ground level and clears all surrounding buildings. I don't think the extra 5 feet in my case makes much difference.

 

[CDX-007]

Marconi, I've been tearing my hair out

trying to understand why the SGM was so consistently down from the AP in your tests.

...then I went back and re-read your chart.

I dunno why, maybe I was expecting to see you list the AP on the left, or 1st, since that was the older of your two antennas.

...so all this time I thought the AP beat out the SGM at your station.

So now you've improved your station performance, too. Excellent!

 

[CDX-007]

007 check this recent post made by Shockwave today.

Originally Posted by Shockwave
I just thought I would mention that my GM was mounted at about the same tip height as my Vector was. The Vector was mounted on a 15 foot pole on my chimney with about 5 feet of mast attached with four chimney straps. I noticed the top U-bolt was tightened to the point where it kinked the mast. Out came the hack saw and I chopped off the bottom 5 feet before installing the GM. I still can't tell the antennas apart other then reduced power handling and added bandwidth. In all fairness, my chimney is over 40 feet above ground level and clears all surrounding buildings. I don't think the extra 5 feet in my case makes much difference.

Oh MY, so the SGM was actually mounted 5' lower above ground than the Vector.

Makes sense why they would be neck-n-neck when I would expect the SGM to outperform the Vector, IF* that explanation from Avanti is accurate. - If so, the Vector is an efficiently fed 1/2 wave radiator and the SGM is an effectively fed full 5/8 radiator with 1.2dB more gain, an 1/8 wave shorter than the factory 3/4 wave Vector.

So effectively, the bottom of the active 1/2 wave of SW's Vector was about 14' higher than the bottom of the active 5/8 part of his SGM. :blink:

If both were erected at equal tip height and tested over reasonably level ground, I would place my bet on the SGM providing gain over the Vector.

*IF

 

[Marconi]

Oh MY, so the SGM was actually mounted 5' lower above ground than the Vector.

That is how he explains it, but at first he says they were at the same tip height and that is the part I don't get.

Makes sense why they would be neck-n-neck when I would expect the SGM to outperform the Vector, IF* that explanation from Avanti is accurate the Vector is an efficiently fed 1/2 wave radiator and the SGM is an effectively fed full 5/8 radiator, an 1/8 wave shorter than the factory 3/4 wave Vector.

So effectively, the bottom of the active 1/2 wave of SW's Vector was about 14' higher than the bottom of the active 5/8 part of his SGM. :blink:

If both were erected at equal tip height and tested over reasonably level ground, I would place my bet on the SGM having gain over the Vector.


*...IF

007, that may be what you might speculate, but that is not what I see here in my own experiences testing similar setups. However, if SW's explanation was the way the setup was and the GM was mounted 5' feet lower and still performed as noted, then IMO, his results are better that he suggested.

BTW and IMO 007, the 5/8 wave is also an end fed 1/8 wave radiator, end feeding a 1/2 wave radiating element, very similar to a Vector end fed 1/4 wave, end feeding a 1/2 wave radiator. The big difference is the 1/4 wave on the Vector is in-phase with the upper 1/2 wave and the whole antenna radiates constructively. Not so with the 1/8 wave segment at the bottom of the 5/8 wave antenna.

 

[CDX-007]

That is how he explains it, but at first he says they were at the same tip height and that is the part I don't get.



007, that may be what you might speculate, but that is not what I see here in my own experiences testing similar setups. However, if SW's explanation was the way the setup was and the GM was mounted 5' feet lower and still performed as noted, then IMO, his results are better that he suggested.

BTW and IMO 007, the 5/8 wave is also an end fed 1/8 wave radiator, end feeding a 1/2 wave radiating element, very similar to a Vector end fed 1/4 wave, end feeding a 1/2 wave radiator. The big difference is the 1/4 wave on the Vector is in-phase with the upper 1/2 wave and the whole antenna radiates constructively. Not so with the 1/8 wave segment at the bottom of the 5/8 wave antenna.

OK, but according to Masterchief's post, 'the dude' from Avanti claimed the bottom ¼ wave of the Vector style antenna, that "Ice cream cone" thingy, doesn't radiate, which I would expect since the currents are of a canceling nature in the base ¼ wave, thus elevating the upper active ½ wave an additional ¼ wave, or 9 feet plus SW's loss of 5 feet = 14 feet down from the Vector's radiator.

- Also, the standard I-10K style bottom/end fed 5/8 doesn't have anything to cancel the base 1/8 of reverse current, except on the Penetrator500 where the highest reverse current is below the elevated radials and sent toward ground instead of canceling as much of the upper in-phase ½ wave as does the 5/8 without elevated radials.

What some have claimed is the Penetrator's downfall, (those darned elevated radials) I believe works to it's benefit.

 

[Marconi]

Don't be too quick to assume minimal interaction between antennas spaced 1 wavelength apart. This happens to be one of the ideal spacing distances when you want two antennas to work as one. To confirm a parasitic interaction, one day I mounted a VHF antenna and took another with no coax and walked it in a circle around the antenna under test at 1 wavelength distance. It absolutely produced nulls and peaks in gain on the antenna under test.

SW, I might agree that one wavelength is too close to be sure, but how did you determine the nulls and peaks?

Once I had my AstroPlane on a 20' foot mast. I had just removed my I-10K and had it on the ground beneath the AP. I went in to run a bandwidth curve with my analyzer and the antenna gave terrible results. I went out and noticed what I had done and wondered. I removed the I-10K and the AP tested well after that. You just never really know.