Some questions about the Stellar Labs 30-2415 antenna - AVS Forum | Home Theater Discussions And Reviews
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post #1 of 16 Old 10-24-2019, 06:04 AM - Thread Starter
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Some questions about the Stellar Labs 30-2415 antenna

I just received a Stellar Labs 30-2415 antenna as a potential spare antenna and after putting it together, I have a few questions for those more familiar with antenna design and use!

1. The three sections must make metal to metal contact in some way but where that happens is not clear. Is it inside the plastic "hinge" on the left side of the picture (which was a part already assembled when I received it)?

2. Do you install it with the bottom section horizontal so the other two are above horizontal?

3. For the part with the balun on the left side of the picture, does it matter if it is installed as pictured, or should it be rotated 180 degrees?

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Last edited by DrDon; 10-24-2019 at 06:36 AM.
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post #2 of 16 Old 10-24-2019, 07:12 AM
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1: You are dealing with RF, so the 3 sections do NOT need to physically touch each other to work

2: The center boom should be slightly above horizontal when installed.

3: The balun installation in the photo is correct. Don't flip it so it's over the top.

This antenna is a Teleaves clone, and while usable, it's not as good as a 91xg type yagi.

Last edited by Primestar31; 10-24-2019 at 07:16 AM.
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post #3 of 16 Old 10-24-2019, 08:35 AM - Thread Starter
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[QUOTE=Primestar31;58725140]
3: The balun installation in the photo is correct. Don't flip it so it's over the top.

If you mean "don't have the connection to the coax cable facing up", yes, I realize that.

I am referring to whether it should be rotated on a VERTICAL axis, so that the horizontal metal part that you can see would not be seen if you rotated 180 degrees on the vertical axis.
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post #4 of 16 Old 10-24-2019, 08:38 AM
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Nice photos, Bud

1. The elements on the three booms in front of the driven element which is connected to the coax are called directors. Directors are parasitic elements that have no connection to other elements. A director picks up the incoming signal which produces a current in the director. Since energy can not be created or destroyed, only converted, the director re-radiates its energy which is picked up by the driven element and adds to the direct signal picked up by the driven element.

2. The mounting brackets are designed so that the center boom will be horizontal. Some UHF antennas, like the 91XG and the HDB91X have tilt brackets so that it is possible to tilt the front end of the antenna up, which is sometimes useful at locations where you are behind a hill. The Stellar Labs 30-2415 antenna does not have a tilt bracket; the antenna would need a mod for tilting.

3. Primestar31 is correct, you have mounted the driven element the right way with the coax connector down and the small metal plate forward as shown in the instructions. The small metal plate acts as a mini-director, so it must be forward.
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Last edited by rabbit73; 10-24-2019 at 09:41 AM.
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post #5 of 16 Old 10-24-2019, 05:30 PM - Thread Starter
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Quote:
Originally Posted by rabbit73 View Post
Nice photos, Bud

1. The elements on the three booms in front of the driven element which is connected to the coax are called directors. Directors are parasitic elements that have no connection to other elements. A director picks up the incoming signal which produces a current in the director. Since energy can not be created or destroyed, only converted, the director re-radiates its energy which is picked up by the driven element and adds to the direct signal picked up by the driven element.

2. The mounting brackets are designed so that the center boom will be horizontal. Some UHF antennas, like the 91XG and the HDB91X have tilt brackets so that it is possible to tilt the front end of the antenna up, which is sometimes useful at locations where you are behind a hill. The Stellar Labs 30-2415 antenna does not have a tilt bracket; the antenna would need a mod for tilting.

3. Primestar31 is correct, you have mounted the driven element the right way with the coax connector down and the small metal plate forward as shown in the instructions. The small metal plate acts as a mini-director, so it must be forward.

Thank you for the very informative post - first thing I did was check my two HDB91X's to see that the driven element was facing the proper direction.

The two brackets are adjustable (tiltable), the same as on the HDB91X antenna.

I appreciate now knowing the specific names for the parts of the antennas. Educational!

I tested the 30-2415 as the Chicago antenna and results appeared similar to those of the HDB91X.
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post #6 of 16 Old 10-26-2019, 01:56 AM
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I bought one of those because it "looked" powerful. It was ok, but the 91X style performed considerably better across the board.. I live in a VERY tough deep fringe signal area .
If you are in a half decent signal area it will work well, it has some gain.. Just not as much as the 91X style.
It is a much more rugged and robust design than the Yagi style though, thats for sure... bob
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post #7 of 16 Old 10-27-2019, 09:02 AM - Thread Starter
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Originally Posted by steel guitar guy View Post
I bought one of those because it "looked" powerful. It was ok, but the 91X style performed considerably better across the board.. I live in a VERY tough deep fringe signal area .
If you are in a half decent signal area it will work well, it has some gain.. Just not as much as the 91X style.
It is a much more rugged and robust design than the Yagi style though, thats for sure... bob
According to rabbit73, Solid Signal's HDB91X is made for them by Qiaohua, which shows a 14-16 dB gain for their AV-91XU (the HDB91X).

The Stellar Labs 30-2415 antenna shows 18 dB gain in their specifications.
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post #8 of 16 Old 10-27-2019, 11:32 AM
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Quote:
Originally Posted by budh9534 View Post
According to rabbit73, Solid Signal's HDB91X is made for them by Qiaohua, which shows a 14-16 dB gain for their AV-91XU (the HDB91X).

The Stellar Labs 30-2415 antenna shows 18 dB gain in their specifications.
The antenna gain figures that you see in descriptions are usually the product of the marketing department rather than from engineering; not to be taken seriously. The current figures from Antennas Direct can be trusted, as can the old specs from Winegard.

Solid Signal says Maximum Gain: 16dB in the HDB91X description, but their Download Technical Document (2) says 23 dB.
https://manuals.solidsignal.com/hdb91x-gainchart.pdf



The amateur radio magazine QST doesn't allow antenna gain figures in ads, because they are often inflated.
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Last edited by rabbit73; 10-27-2019 at 06:33 PM.
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post #9 of 16 Old 10-29-2019, 08:35 AM
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Quote:
Originally Posted by steel guitar guy View Post
I bought one of those because it "looked" powerful. It was ok, but the 91X style performed considerably better across the board.. I live in a VERY tough deep fringe signal area .
If you are in a half decent signal area it will work well, it has some gain.. Just not as much as the 91X style.
It is a much more rugged and robust design than the Yagi style though, thats for sure... bob
The triple boom yagi indeed looks powerful since it has three booms of reflector elements rather than one. And is probably modeled somewhat after the renowned Televes version. The HD91X is the generic version of the 91XG from Antennas Direct, and has been a proven strong performer. The Solid Signal version appears identical to the Newark version, which has a very good promo price about $20 currently.
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post #10 of 16 Old 10-29-2019, 09:31 AM
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Quote:
Originally Posted by tylerSC View Post
The triple boom yagi indeed looks powerful since it has three booms of reflector elements rather than one. And is probably modeled somewhat after the renowned Televes version.
The elements on the three booms in front of the driven element are directors not reflectors. The corner reflector is behind the driven element.

The three booms do make it look more powerful, but I'm not sure that it actually does make it more powerful to any significant degree. See previous thread:
Anyone Tried Steller Labs 30-2415 Yagi Antenna ?
10-23-2014
https://www.avsforum.com/forum/25-hd...i-antenna.html
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Last edited by rabbit73; 10-29-2019 at 12:07 PM.
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post #11 of 16 Old 10-29-2019, 01:09 PM
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Quote:
Originally Posted by rabbit73 View Post
The three booms do make it look more powerful, but I'm not sure that it actually does make it more powerful to any significant degree.

Here's what HDTV Primer has to say about this antenna:

http://www.hdtvprimer.com/ANTENNAS/DAT75.html

As he points out the three sets of directors have partially overlapping apertures which means they're receiving the same signal and therefore don't increase the gain much over one yagi. This is the same thing that happens if you stack yagis too close together.
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post #12 of 16 Old 10-29-2019, 02:18 PM
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Originally Posted by Calaveras View Post
....... three sets of directors have partially overlapping apertures which means they're receiving the same signal and therefore don't increase the gain much over one yagi. This is the same thing that happens if you stack yagis too close together.
Thank you; that confirms my doubts about the design.

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post #13 of 16 Old 10-30-2019, 10:52 AM
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Originally Posted by rabbit73 View Post
Solid Signal says Maximum Gain: 16dB in the HDB91X description, but their Download Technical Document (2) says 23 dB.
But remember that for US television, 600 MHz (well, 608 MHz) is "now" the highest frequency used. From the chart, I might have said 19 dB.
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post #14 of 16 Old 11-04-2019, 07:20 PM
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Quote:
Originally Posted by Calaveras View Post
Here's what HDTV Primer has to say about this antenna:

http://www.hdtvprimer.com/ANTENNAS/DAT75.html

As he points out the three sets of directors have partially overlapping apertures which means they're receiving the same signal and therefore don't increase the gain much over one yagi. This is the same thing that happens if you stack yagis too close together.
Also,
Quote:
The only place where they are more effective than one Yagi is in the channel 38-55 range where the Yagis are just starting to work but don’t yet overlap.
Quote:
Originally Posted by gbynum View Post
But remember that for US television, 600 MHz (well, 608 MHz) is "now" the highest frequency used. From the chart, I might have said 19 dB.
Sounds like it would've been a decent antenna for the last decade. But no longer, unless/until someone scales it up to the new UHF band.
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post #15 of 16 Old 11-06-2019, 05:16 PM
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Also,Sounds like it would've been a decent antenna for the last decade. But no longer, unless/until someone scales it up to the new UHF band.
Three sets of directors in close proximity behave virtually the same as one set of directors.
The three boom design merely gives slightly wider vertical beamwidth and slightly wider frequency bandwidth.
With the exception of Winegard, quoted gain figures and ranges are greatly exaggerated on consumer grade tv antennas.
No consumer UHF antenna sold has more than 16 Dbi peak gain and that gain figure is only on the highest channels no longer in use.
Gain on lower UHF channels is far less especially with any yagi design.
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post #16 of 16 Old 11-06-2019, 06:50 PM
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Well, yes. 16 dBi gain is only on the highest channels no longer in use. Which was my point.

If you scale up the antenna, you'd increase its dimensions horizontally, vertically, and in depth. Increasing the vertical dimension would increase the separation between the three sets of directors, so they would no longer overlap so completely at the channels still in use. You'd have to make it 30% larger in every dimension to get that benefit though. That's a lot more metal - if you increase all dimensions by 30%, including thickness, it's more than double - but you could probably eliminate the middle Yagi entirely, clawing back 1/3 of the cost without losing much gain.

That still makes it 50% more expensive, and I don't know if anyone has analyzed that modification.

I'm unsure of the benefit of slightly wider vertical vs. horizontal beam width. It could be useful in certain situations, but YMMV.
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