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post #1 of 9 (permalink) Old 2019-11-16, 09:46 AM Thread Starter
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Aloha from a novice in HI

Aloha guys, I've been lurking various forums on and off for a few years. You guys are off the charts knowledgeable and never cease to amaze me. Ive been playing with a few cheap store bought antennas recently. The RCA 7511, for exampl, and right now one of the Chinese craptennas with rotator. My OTAs are close, but spread out, and nothing I have experimented with has worked even marginally well. I am now ready to just build one. I would love to hear a few thoughts and suggestions about what might be best suited to my situation. I am leaning towards one of Nikimls GH models possibly the GH4n2 but I am constantly rethinking. I have learned so much and still feel like I'm completely in the dark about this subject. Any help would be welcomed. Here is my report. https://www.rabbitears.info/searchma...study_id=28246
Maybe you guys can turn the light on finally. TIA
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post #2 of 9 (permalink) Old 2019-11-16, 02:18 PM
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Quote:
Originally Posted by HawaiiOTAGuy View Post
My OTAs are close, but spread out, and nothing I have experimented with has worked even marginally well.....Here is my report. https://www.rabbitears.info/searchma...study_id=28246
Maybe you guys can turn the light on finally. TIA
Hello, HawaiiOTAGuy; welcome to the forum.

Thank you for the signal report; that's the first from Hawaii that I've seen in 10 years of helping with reception problems.





This is an image of your report:



Yes, they are spread out. Your antenna system will depend upon which channels are important to you.

Where will your antenna be located?

How many TVs will be on the antenna?

Why is the present reception not even marginally good: they are spread out, they are too weak, or what?

The antennas you are considering are primarily UHF antennas, but you also have some VHF-High channels.

Although the transmitters are close, your elevation is much higher (except for K45CT), and there is terrain interference to the signals. Click on Transmitter Distance in your report to see the terrain profile for a channel.



You will need an antenna with more VHF gain for real channels 11, 9, and 13. Maybe a Stellar Labs 30-2475 combined with your UHF antenna with a UVSJ UHF/VHF combiner.

If you can not measure it, you can not improve it.
Lord Kelvin, 1883

Last edited by rabbit73; 2019-11-16 at 03:54 PM.
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post #3 of 9 (permalink) Old 2019-11-16, 10:09 PM Thread Starter
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Aloha Rabbit, you are actually one of the antenna geniuses I was referring to. Kudos for all the help you give in many different places. You are a rockstar IMHO. Now to the task at hand. With the RCA yagi I was able to catch only the 4-##(13) stations and 14(23). Without training that was the extent of it and even those were spotty. Fading in and out. I am hoping to get at least the majors. I have yet to pull in the FOX/CW (11) station at all, But did manage to get the CBS (9). All of these are on the same tower. With rotation I can get NBC(13), and PBS comes in from quite a few directions. I was hoping to build something that could at least receive the stations I mentioned, without rotation. Shipping to Hawaii is expensive also, so if I could build one it wouldn't stretch our already tight budget too much. Right now I am only using one TV, but it would be a boon to have all TVs able to receive OTA. I love my NFL and it is killing our data trying to watch via mobile. Not to mention cell signals are also hit and miss where we live. I know I am probably hoping for too much, but you never get what you don't try for.
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post #4 of 9 (permalink) Old 2019-11-16, 10:33 PM Thread Starter
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Since I can't edit my post, I have to add another to say my antenna is installed on the gable of the house about 15ft above the ground. I think that answers the questions you asked in your reply. Mahalo for your time.
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post #5 of 9 (permalink) Old 2019-11-16, 11:00 PM
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15 ft is quite low for an outdoor tv antenna.
The FCC, and thus all broadcasters assume the user is using an outdoor antenna 10m above ground in doing all of their analysis/planning.
I too would recommend a VHF Hi yagi separate from your UHF antenna. But do understand the shipping cost to Hawaii can be excessive
(family who lived there for a few years)...
You haven't answered a critical question though, how many TVs / tuners do you plan on driving with the antenna system?

DB8E/VHF Yagi rotor FM Bandstop ap-8700 preamp 8way split LG lcd.
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post #6 of 9 (permalink) Old 2019-11-17, 12:49 AM Thread Starter
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Quote:
Originally Posted by majortom View Post
15 ft is quite low for an outdoor tv antenna.
The FCC, and thus all broadcasters assume the user is using an outdoor antenna 10m above ground in doing all of their analysis/planning.
It is probably closer to 7m or a tad higher. I added some height today. Low pitch on roofs here makes anything more a rather large undertaking (1 ft below grade is solid rock).

Quote:
You haven't answered a critical question though, how many TVs / tuners do you plan on driving with the antenna system?
I would be completely satisfied with a single TV/Tuner, a 2nd would be awesome but not necessary.
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post #7 of 9 (permalink) Old 2019-11-17, 05:30 AM
 
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Omni-directional horizontally polarized antenna is very hard case.

https://ypylypenko.livejournal.com/37053.html
https://ypylypenko.livejournal.com/37335.html

I would suggest stack of 2 "korona"-style antennas, phased with slight down-tilt

For VHF - same "korona"-style, using UHF/VHF diplexer to combine signals
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post #8 of 9 (permalink) Old 2019-11-17, 11:23 AM
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Just to check the signal path, here is a terrain profile using different software:



If extra antenna gain isn't enough for reliable reception, you might need a preamp.

If you give me your address in a PM (private forum message), I can check the satellite view.

If you can not measure it, you can not improve it.
Lord Kelvin, 1883

Last edited by rabbit73; 2019-11-17 at 11:41 AM.
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post #9 of 9 (permalink) Old 2019-11-18, 12:26 PM
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Quote:
Originally Posted by HawaiiOTAGuy
Sitting here this morning trying to watch the CBS affiliate (45) which is my higher elevation tower and the signal is strong and seems perfect for a while and then it's gone. That's the one channel, it seems to me, should be good with antenna pointing at it, frustrating
Thank you for the additional information by PM. K45CT is a low power translator that is only running 13.5 kW ERP and its antenna is only 46 feet above ground level at that location. A tower that high is called a "short stick."
https://www.rabbitears.info/tvq.php?...ms&facid=34446

I did two terrain profiles that show the signal grazes the surface of the ground on its path to your antenna. A taller transmitting tower would have helped.





I think you will need a UHF antenna with good gain and a preamp for improved reception of K45CT.

Does your TV have a signal strength indicator to tell you if any changes you make in your antenna system improved the signal strength?

When I looked at the satellite and ground photos of your location I see a lot of trees up a hill just north of your location in the KHAW signal path. The ground photos were taken in 2011. Has that lot been sold and the trees cut down?

There are also trees across the street in that old photo, but I don't think they are in the K45CT signal path.
http://www.hdtvprimer.com/ANTENNAS/siting.html
scroll down to Trees and UHF

If you can not measure it, you can not improve it.
Lord Kelvin, 1883

Last edited by rabbit73; 2019-11-18 at 05:03 PM.
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