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Old 20-Apr-2017, 11:36 PM   #21
OTAFAN
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Unhappy Rca ant751

Yeah, I think we're preaching to the choir here. And each time I've seen new advertisements of this antenna, RCA ups the receiving distance. On their website, it has always stated approximately 40 miles. Now it's up to 70 with the removal of some critical elements, no less! Well, my advise is to hang on to your original 751s or grab one if you see it before they replace them all with the "new and improved" 7511. But it will be interesting to see your comparisons with the new GE Indoor Attic Antenna and RCA 7511, rabbit73. I'm going to take a crap shoot and say the GE will equal or perhaps outperform the RCA 7511 by a small margin. How 'bout a wager???
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Old 20-Apr-2017, 11:40 PM   #22
rabbit73
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Quote:
I would be very interested in your testing results of the new GE Indoor Attic Antenna. Feedback on Amazon has been surprisingly good.
I have been having a lot of fun with it. At my present location an indoor antenna is necessary for OTA reception. We also have basic cable, but I love to play with antennas and make antenna measurements.

I started experimenting with antennas when I was 8; I'm now 84. I have built many ham and TV antennas, and am still fascinated by the magic.

The GE Attic Antenna 34792 comes requiring assembly; this video showed me what to expect:
https://www.youtube.com/watch?v=1qYucg3JXzA

The signals are quite strong here, so I can get away with an indoor antenna on the ground floor, in spite of buildings and trees in the signal path. The GE antenna has more gain on UHF than on VHF-High; the UHF section is a yagi with a curved reflector, but it only has a folded dipole for VHF-High. As a result, although channel 13 is listed on my report almost as strong as the UHF signals, it is a lot weaker at the tuner because the antenna has less gain on VHF than UHF.

I have added an RCA TVPRAMP1R preamp to help 13, but I have found that the antenna location indoors is critical because of multipath reflections. Even though the signal might be strong enough, the tuner might not be able to decode it because it has reduced signal quality from multipath reflections.

Notes and photo of antenna added to screen shot of Sony Diagnostics Screen:



Attached Images
File Type: jpg My Report 3-2-2017 (2).jpg (320.9 KB, 132 views)
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Last edited by rabbit73; 21-Apr-2017 at 1:50 AM.
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Old 21-Apr-2017, 12:00 AM   #23
OTAFAN
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Smile Rca ant751

I share your enthusiasm and fascination with OTA TV and radio as well. I don't have a tech background like you and ADTech, but I really enjoy the mysteries of what has turned into a hobby for me. That's why I was so thankful I came across TV Fool one day while surfing the web. And then receiving the helpful replies from you has been greatly appreciated, rabbit73. Thanks for the input on your new GE antenna. It will be interesting to see how it compares with the RCA7511 and how quickly others respond to it. In the meantime, I'm also looking at a couple of antennas from Antennas Direct, as they have good reports for both indoor and outdoor reception. I'm sure I'll have many more questions, so as they say, "stay tuned." I'll be back.....
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Old 21-Apr-2017, 12:11 AM   #24
OTAFAN
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Rca ant751

P.S. I just noticed your Signal Diagnostics Screen report. Your SNR is 34, but your signal strength is 57. You have a Sony TV, but on my Samsung if I had an SNR of 34, my signal strength would be 100%. I'm uncertain about this other than Samsung does it different than Sony. Any thoughts? Thanks.
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Old 21-Apr-2017, 1:16 AM   #25
rabbit73
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The signal strength scale on TVs is just a relative scale; the scale will vary from brand to brand, and it isn't even the same on my different model Sony TVs.

The important thing is that you can use it for comparisons, like how weak can a signal be and still be received. Or you can use it for aiming an antenna while watching signal strength and signal quality as defined by SNR and uncorrected errors.

I used my signal level meter to calibrate the signal strength scale of my KDL32R400A:



In the screen shot channel 16 measured 57 on the Sony, which is equal to -2 dBmV which is equal to -51 dBm. Channel 16 on my report is listed as having a signal power of -29 dBm, so the signal at the tuner is 22 dB weaker than listed. The signal is weaker inside because of the building and tree loss. but it is made a little stronger because of the antenna gain (on UHF). The report assumes that a simple dipole antenna is used; that is the reference for a 0 dB NM signal.
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File Type: jpg SSCHART KDL32R400A4.jpg (185.6 KB, 116 views)
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Last edited by rabbit73; 22-Apr-2017 at 2:45 AM.
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Old 22-Apr-2017, 7:00 AM   #26
OTAFAN
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Rca ant751

I found an initial answer to the question I posed to rabbit73 above regarding how the "new and improved" RCA ANT7511 would compare to the previous versions of the ANT751. It was a reply from holl_ands on the AVS Forum in a thread on the antenna subsection back on 12/28/2016. Here is what he said:

IF you provide detailed Measurements and multiple PHOTOS (incl. a RULER in the Photo), then I can TRY to model ANT-7511 ES (or most any other Antenna of interest). But I haven't published 4nec2 Results for ANT-751 because Log-Yagi's (ditto YA-1713) do NOT model very well on the upper frequencies wrt Gain and SWR for ANT-751 was "off"....I suspect I need pricey NEC4 Engine to model the Cross-Over Feedlines and hopefully eliminate these shortcomings.

UHF portion of ANT-751 and ANT-7611 ES are SLIGHTLY different...but not by much and SAME number of UHF Elements....so, probably about the same UHF Gain....as given in Spec Sheet for HD-7000, from which the UHF part of ANT-751 was derived:
http://manuals.solidsignal.com/HD7000R.pdf

My simplified 4nec2 model for the ANT-751R/EZHD calculated 6.3 dBi (Minimum at band edges) to 7.5 dBi (Max Mid-Band) Hi-VHF Gain. When I removed the most forward Hi-VHF Director to emulate the ANT-7511 (although without SAME Element Spacings) it is reduced to 5.6 dBi (Minimum at band edges) to 7.0 dBi (Max Mid-Band). So only 0.5 to 0.7 dB reduction in Hi-VHF Gain.

FYI: Slightly higher Hi-VHF Gain numbers (esp. on upper Channels) were found when I OPTIMIZED 3 and 4-Element Hi-VHF Yagi's [which tend to provide more Gain than Log-Yagi's, esp. on higher frequencies], using Folded-Dipole Active Elements designed for Hi-VHF Band....rather than going THROUGH the UHF Folded Dipole Active Element, as done in the ANT-751 Log-Yagi [UHF Dipole and TWO Hi-VHF Active Elements form a 3-Element LPDA structure]...which is clearly causing some minor degradation, esp. on Ch12/13:
http://imageevent.com/holl_ands/yagis/hivhf3elfdyagiopt
http://imageevent.com/holl_ands/yagis/hivhf4elfdyagiopt

Here is where I actually found the above comment:

http://www.avsforum.com/forum/25-hdt...ntenna-related

So it appears from his findings that there is a small loss in gain from the RCA ANT7511 to the ANT751, if I'm reading him correctly. Any thoughts?
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Old 22-Apr-2017, 7:09 AM   #27
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Rca ant751

P.S. The above quoted comment is specifically found in the HDTV Technical section on the AVS Forum.
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Old 22-Apr-2017, 6:29 PM   #28
rabbit73
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Ah, yes; I remember that thread:

first post by kram1
http://www.avsforum.com/forum/25-hdt...l#post48491929

post by kram1 showing two boxes

He said he bought the 751, but he bought the 7511

http://www.avsforum.com/forum/25-hdt...l#post48525657



post by kram1 showing ANT7511 up

http://www.avsforum.com/forum/25-hdt...l#post49316025



post by holl_ands that you quoted

http://www.avsforum.com/forum/25-hdt...l#post49348785

The gain figures that holl_ands gave are only estimates, but I am inclined to agree with him. He is very good at antenna modeling, but isn't able to model LPDAs with great accuracy because of software limitations.
Attached Images
File Type: jpg kram1avsRCAANT751boxes_1.jpg (140.1 KB, 67 views)
File Type: jpg kram1avsRCAANT7511up_1.jpg (118.1 KB, 64 views)
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Last edited by rabbit73; 22-Apr-2017 at 7:10 PM.
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Old Yesterday, 7:16 PM   #29
rabbit73
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I made some measurements indoors to compare the GE 34792 Attic Antenna with the RCA ANT7511 Antenna. They are not exactly antenna test range measurements that an engineer would do, and they are not quite as accurate as I used to be able to do when I mounted two antennas side-by-side on my car and used stable LOS signals. But, I think they are useful because I used my Sadelco DisplayMax 800 Signal Level Meter in the single channel scan mode.

The meter makes many measurements across a TV channel during a single channel scan, as a spectrum analyzer would do, and calculates the average of all the measurements. I used an RCA TVPRAMP1R preamp and a splitter to feed the meter and my Sony KDL32R400A TV.



The GE antenna did a little better on channel 7, even though it only has a folded dipole for VHF. The RCA antenna did better on channel 13, as would be expected with 3 VHF elements.

UHF comparison coming soon.
Attached Images
File Type: jpg GE34792vsRCAANT7511vhf.jpg (210.4 KB, 39 views)
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Last edited by rabbit73; Yesterday at 11:01 PM.
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Old Yesterday, 10:45 PM   #30
rabbit73
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The GE antenna is much better on channel 16, and a little better on 29, than the RCA ANT7511 (at this location). The RCA doesn't look like it would be suitable for UHF after repack.
Attached Images
File Type: jpg GE34792vsRCAANT7511uhf.jpg (230.1 KB, 22 views)
__________________
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Last edited by rabbit73; Today at 12:46 AM.
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Old Today, 12:30 AM   #31
OTAFAN
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Smile Rca ant751

Wow, rabbit73.....you're THE MAN! Excellent testing especially given indoors and limits of your current situation from what you used to be able to door with your outdoor set up. And unfortunately, the updated RCA 7511 doesn't appear to compete with the newer indoor GE Attic; as compared to it's very successful former RCA 751. My advise would be to grab a long box 751 if you can find one while you still can! Thanks a million, rabbit73! We're fortunate to have your expertise and input on TV Fool!!
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Old Today, 12:38 AM   #32
rabbit73
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Thanks for your kind words; glad you enjoyed it. It was an interesting project for me, because many people can only have an indoor antenna.

Now I'm wondering how a 751 would compare with a 7511.
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