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OTAFAN
11-Apr-2017, 7:17 PM
Which elements on the boom of the RCA ANT751 are for UHF and VHF High reception? I've had good use of this antenna for some time now, but was a bit confused as to which are being used for the various TV frequencies; especially since it does not have a reflector behind the UHF elements as is typical. Any help would be appreciated. Thanks! OTAFAN

ADTech
12-Apr-2017, 12:59 AM
are for UHF The short ones.

VHF High The long ones.

OTAFAN
12-Apr-2017, 1:29 AM
Well, that's interesting ADTech. So, there's 3 short UHF antenna elements in front and 4 long VHF High elements, although there is a gap between the first 3 longer elements and the last longest element at the far back of the boom. Any idea what that gap is for? And with so few elements on the ANT751, it really is quite a good performer across the TV frequencies. At least it has been for me. Any idea what its secret for success has been? Thanks again for your help!

rabbit73
12-Apr-2017, 1:53 AM
One secret is that the UHF driven element is a tetrapole, in the original version of the 751.

RCA likes to change the design in mid stream without changing the model number, usually to meet a price point with the loss of some performance.

Another secret is that the VHF section is an LPDA.

Another secret is that it is an original Winegard design.

http://forum.tvfool.com/attachment.php?attachmentid=2609&stc=1&d=1491962552

http://forum.tvfool.com/attachment.php?attachmentid=2531&stc=1&d=1483891000

http://forum.tvfool.com/attachment.php?attachmentid=2610&stc=1&d=1491962883

http://forum.tvfool.com/attachment.php?attachmentid=2613&stc=1&d=1492047489

http://forum.tvfool.com/attachment.php?attachmentid=2611&stc=1&d=1491963344

And with so few elements on the ANT751, it really is quite a good performer across the TV frequencies.A lot of good reports from users in strong signal areas.

Any idea what that gap is for?Ask holl_ands. He does computer modeling of antennas. You can find him here:
http://www.avsforum.com/forum/25-hdtv-technical/
or here:
http://www.digitalhome.ca/forum/186-antenna-research-development/

OTAFAN
12-Apr-2017, 2:36 AM
Wow, thanks for the antenna primer, rabbit73! I appreciate better now my antenna set up. BTW, I called RCA earlier and asked them the same question I posed on this forum. The CS Rep told me in no uncertain, but friendly terms, that they could NOT answer my question because it was "proprietary information." ???!!! I pressed them for an answer since their antenna was a yagi design and had been around for nearly a century, but to no avail. I didn't understand the secrecy in this case. But tight lipped they remained. So, thanks again to TV Fool for revealing the mysteries of TV antenna theory for dummies like me! You folks are very much appreciated!! OTAFAN now more enlightened.....

rabbit73
12-Apr-2017, 2:45 AM
The UHF section is a yagi, but the VHF section is not a yagi, it is a LPDA.
https://en.wikipedia.org/wiki/Log-periodic_antenna

OTAFAN
12-Apr-2017, 3:15 AM
Yes, understood rabbit73. I see that this antenna is a combination that I didn't know about before. You certainly have clarified the issue. Unfortunately, RCA wasn't able to educate me further in this good hobby of mine. But as long as we have TV Fool.....

ADTech
13-Apr-2017, 8:26 PM
BTW, I called RCA earlier and asked them the same question I posed on this forum. The CS Rep told me in no uncertain, but friendly terms, that they could NOT answer my question because it was "proprietary information." ???!!! I pressed them for an answer since their antenna was a yagi design and had been around for nearly a century, but to no avail. I didn't understand the secrecy in this case. But tight lipped they remained.I can GUARANTEE you that they were tight-lipped because they didn't have a clue as to the correct answer. FWIW, the antenna is manufactured for VOXX (owner of the old RCA trademark) by Winegard. It is a derivative of their old HD7000R antenna which was discontinued a few years ago but then was relaunched last year with a feature that allows extra metal to be bolted on to make it convertible between a 2-uhf or a 7-UHF model.

OTAFAN
13-Apr-2017, 10:11 PM
Thanks much for the follow-up ADTech! Very interesting indeed. Between your replies and rabbit73 info provided, I've become much more enlightened as to how my antenna set up works. Since OTA TV has always been my go to for viewing, I've increasingly grown curious as to how it all works. TV Fool has been extremely helpful in directing me to continue my life long learning in this field. And both you and rabbit73 have always been willing to answer my questions. I can't thank you enough and I'm sure I echo many on this forum. BTW, I found a place on the RCA web site where one could post questions to an RCA Engineer. So, nothing left to loose I emailed them and to my surprise, I just received an answer to my initial question. And the response was.....exactly what you first said here in this thread--shorter elements UHF and longer VHF High. So, to be fair to RCA (or rather VOXX), I was able to get something out of their "proprietary information!" But I think I will keep posting my future questions first on this forum. I know I will get help here. Best to you ADTech!

OTAFAN
14-Apr-2017, 6:09 PM
P.S. I received another reply from RCA Engineer which was appreciated and obviously they are willing to discuss their antenna in spite of CS claiming "proprietary information," as I mentioned above. But they referred to the ANT751 as a "Yagi style." Rabbit73 said the back of the antenna used for VHF High was an LPDA. So, I'm now a bit confused again as to which is which??? Any follow up would help. Here is the comment from RCA regarding the gap between the two last elements on the back of the boom:


"The longer element is called a reflector element and its length and distance from the other elements is a calculation based upon factors such as gain, front to back ratio, the bandwidths that the antenna is designed to receive, and the pattern desired by the antenna designer for the antenna reception. In a traditional Yagi style antenna, the reflector is typically longer than the other elements in the antenna."

ADTech
14-Apr-2017, 6:39 PM
The UHF section is a simple UHF Yagi structure with a parasitic element that is probably there to flatten the bandwidth.

The VHF section, is not a Yagi as the two rear most elements are connected to each other with phasing lines which excludes that section from being a conventional Yagi but is rather a log-periodic design. The two long elements clipped to the underside of the boom are probably there for the same reason as the parasitic element on the UHF side.

I haven't tried modelling the antenna (not my cup of tea) but I did test it on my backyard antenna test range late last summer and compared it to several other antennas. Might have to dig out those spreadsheets and see what things look like.

rabbit73
15-Apr-2017, 8:31 PM
The UHF section is a simple UHF Yagi structure with a parasitic element that is probably there to flatten the bandwidth.

The VHF section, is not a Yagi as the two rear most elements are connected to each other with phasing lines which excludes that section from being a conventional Yagi but is rather a log-periodic design. The two long elements clipped to the underside of the boom are probably there for the same reason as the parasitic element on the UHF side.I agree.

The two long elements on the underside are parasitic directors for VHF-High, which would make the four rear elements a hybrid called a log-yagi for VHF-High.

http://forum.tvfool.com/attachment.php?attachmentid=2614&stc=1&d=1492288237

OTAFAN
16-Apr-2017, 12:16 AM
A picture says a thousand words! And I also found it helpful to read this:

https://en.wikipedia.org/wiki/Log-periodic_antenna

Thanks again rabbit73! I owe you guys a cup of coffee or a free prize at Antennas Direct!!

rabbit73
16-Apr-2017, 2:09 PM
Diagram revised:

http://forum.tvfool.com/attachment.php?attachmentid=2617&stc=1&d=1492351076

I suspect that the insulated UHF parasitic element in front of the UHF driven element Tetrapole is actually a pair of side-by-side directors that you also see in high gain UHF yagis by other manufacturers. The Tetrapole, AKA 3/4 wave folded dipole, has two current loops that allow the use of pairs of directors in front of it for maximum gain. But, I can't be certain until I have a 751 in front of me to confirm it.

http://forum.tvfool.com/attachment.php?attachmentid=2613&d=1492047521

You can see the idea of director pairs in Winegard patent 3,518,693. The patent drawing shows pairs of directors, but the patent text claims "a plurality of director elements."

http://forum.tvfool.com/attachment.php?attachmentid=2618&stc=1&d=1492362159

rabbit73
20-Apr-2017, 2:40 AM
Definitely a pair of directors in front of the Tetrapole.

http://forum.tvfool.com/attachment.php?attachmentid=2624&stc=1&d=1492655892

http://forum.tvfool.com/attachment.php?attachmentid=2625&stc=1&d=1492655892

rabbit73
20-Apr-2017, 2:53 AM
CAUTION, there is a new version being sold, and they are using the photo of the original ANT751; very misleading.

RCA Suburban Mini Yagi Digital Outdoor Antenna with Mast, now model ANT7511

Differences:

1. The mast clamp is now ahead of the rear element
2. There is only one VHF director
3. The 4 shorting stubs have been replaced with 2 small-diameter wires, each 5-1/2" long
4. The Tetrapole has been replaced with a long dipole driven element; 6-1/2" long on each side
5. The UHF director pair in front of the Tetrapole has been replaced with a conventional director, for a total of 3 directors, each 7" long

http://forum.tvfool.com/attachment.php?attachmentid=2626&stc=1&d=1492658157

http://forum.tvfool.com/attachment.php?attachmentid=2627&stc=1&d=1492659580

OTAFAN
20-Apr-2017, 8:55 AM
So.....I'm guessing that RCA's newest revision of their popular ANT751 or rather now, 7511, could be a step back in performance? What was their thinking here? And why mess with success??? I suppose we'll have to wait for in field testing by you guys and others who happen to purchase it. Fingers crossed for those who have yet to use it. Well, rabbit73, you certainly deserve another cup of coffee on me or prize from Antennas Direct, or both! Let me know I'm good for it.....Thanks so much again for going the extra mile here.....

rabbit73
20-Apr-2017, 1:58 PM
So.....I'm guessing that RCA's newest revision of their popular ANT751 or rather now, 7511, could be a step back in performance?My guess would be the same.
What was their thinking here?To make it cheaper, not better.
And why mess with success???More profit.
I suppose we'll have to wait for in field testing by you guys and others who happen to purchase it.I would love to be able to compare it with the original 751, but I don't have one. I thought I was getting an original 751 when I ordered it. Even if I had both, I wouldn't be able to make a good comparison at my present location as I previously was able to do like this:

http://forum.tvfool.com/attachment.php?attachmentid=2615&stc=1&d=1492307620

With the setup above I was able to use a steady OTA signal and switch back an forth between the two antennas with an A/B switch while reading my signal level meter.

I do plan to compare it with my GE attic antenna for indoor reception, and I still have a signal level meter, or two.

http://i496.photobucket.com/albums/rr328/rabbit73_photos/IMG_0144_1_1.jpg (http://s496.photobucket.com/user/rabbit73_photos/media/IMG_0144_1_1.jpg.html)

OTAFAN
20-Apr-2017, 7:25 PM
Well, I understand we all need our paycheck at the end of the day, including the bossman! But if sales off Amazon are any indication of the 751s success, I guess RCA must figure you can never have enough??? And they obviously have cut corners on their 7511 revision to the probable downgrade of their product for their customers. So it goes. BTW rabbit73, I would be very interested in your testing results of the new GE Indoor Attic Antenna. Feedback on Amazon has been surprisingly good. Please post when you can. Thanks, as always, for your generous support and help on TV Fool!

rabbit73
20-Apr-2017, 10:56 PM
Not only are the companies that are selling the ANT7511 using the image of the original ANT751, but the box for the ANT7511 has images of the original ANT751. The worker that pasted the ANT7511 sticker on the box, put it on at an angle, so that it is possible to see the printing ANT752Z.

My guess it that first RCA wanted a smaller box, so they made the boom in two pieces. Then, they said why stop there, let's see what we can remove to cut costs even more, so the ANT7511 was born......Ugh!

http://forum.tvfool.com/attachment.php?attachmentid=2628&stc=1&d=1492728873

http://forum.tvfool.com/attachment.php?attachmentid=2629&stc=1&d=1492728873

OTAFAN
20-Apr-2017, 11:36 PM
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???

rabbit73
20-Apr-2017, 11:40 PM
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:

http://forum.tvfool.com/attachment.php?attachmentid=2558&stc=1&d=1486828373

http://forum.tvfool.com/attachment.php?attachmentid=2630&stc=1&d=1492732056

OTAFAN
21-Apr-2017, 12:00 AM
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.....

OTAFAN
21-Apr-2017, 12:11 AM
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.

rabbit73
21-Apr-2017, 1:16 AM
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:

http://forum.tvfool.com/attachment.php?attachmentid=2631&stc=1&d=1492737324

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.

OTAFAN
22-Apr-2017, 7:00 AM
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-hdtv-technical/381623-official-avs-antenna-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?

OTAFAN
22-Apr-2017, 7:09 AM
P.S. The above quoted comment is specifically found in the HDTV Technical section on the AVS Forum.

rabbit73
22-Apr-2017, 6:29 PM
Ah, yes; I remember that thread:

first post by kram1
http://www.avsforum.com/forum/25-hdtv-technical/381623-official-avs-antenna-related-hardware-topic-551.html#post48491929

post by kram1 showing two boxes

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

http://www.avsforum.com/forum/25-hdtv-technical/381623-official-avs-antenna-related-hardware-topic-552.html#post48525657

http://forum.tvfool.com/attachment.php?attachmentid=2632&stc=1&d=1492886569

post by kram1 showing ANT7511 up

http://www.avsforum.com/forum/25-hdtv-technical/381623-official-avs-antenna-related-hardware-topic-553.html#post49316025

http://forum.tvfool.com/attachment.php?attachmentid=2633&stc=1&d=1492887539

post by holl_ands that you quoted

http://www.avsforum.com/forum/25-hdtv-technical/381623-official-avs-antenna-related-hardware-topic-553.html#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.

rabbit73
28-Apr-2017, 7:16 PM
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.

http://forum.tvfool.com/attachment.php?attachmentid=2634&stc=1&d=1493406880

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.

rabbit73
28-Apr-2017, 10:45 PM
http://forum.tvfool.com/attachment.php?attachmentid=2635&stc=1&d=1493419398

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, but please keep in mind that my measurements indicate how the antennas performed at my location and it might not be an accurate indication of the actual gain of the antennas.

OTAFAN
29-Apr-2017, 12:30 AM
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!!

rabbit73
29-Apr-2017, 12:38 AM
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.:)

rabbit73
1-May-2017, 2:45 PM
I found an RCA ANT751R on ebay with free shipping. The seller showed a photo of the long unopened box, so I was fairly certain it would be the original. It was the original when it arrived, and he sent it Priority Mail.

Most of the other sellers show a stock image of the unfolded 751, but no photo of the box, so it is hard to tell if is a 751 or 7511 especially when they use various UPCs.

The UPC on my ANT751R box is 0 44476 06452 4. Unfortunately, the UPC bar code on the short 7511 box is the same.:eek:

So, I guess the most reliable indicator is the box length, because the boom for the 7511 comes in two pieces, but the boom for the longer 751R is in one piece.

I compared the 751R with my GE Attic antenna as a standard. The VHF signals were a little weaker that day, but it is the comparison that counts.

GE 34792 Attic Antenna vs Original RCA ANT751R

GE 34792 RCA ANT751R TVFOOL
Ch dBmV = dBm dBmV = dBm Report dBm

7 0.3 -48.5 0.4 -48.4 -41.4
13 1.6 -47.2 1.5 -47.3 -37.6
16 14.2 -34.6 7.8 -41.0 -29.0
29 14.8 -34.0 12.9 -35.9 -29.5
40 8.1 -40.7 9.1 -39.7 -29.8

TEST CONDITIONS
Antennas indoors on ground floor, many trees
and buildings in the signal path.
EQUIPMENT
Antennas, RCA TVPRAMP1R preamp, 2-way splitter,
Sadelco DisplayMax 800 signal level meter,
Sony KDL32BX320 TV

Antenna > preamp > power > splitter > meter & TV
inserter


The 751R is a LOT better than the 7511 on channel 16, but not as good as the GE. The GE Attic Antenna is designed for indoor use only. It's not rugged enough for outdoor use.
My advise would be to grab a long box 751 if you can find one while you still can!Good advice.

The RCA antennas are kind of messy to unfold; they have a coating of oil that comes off on your hands. The thin flat elements are easier to unfold with gloves on because they have sharp edges.

ADTech
1-May-2017, 11:56 PM
Might have some interesting test data after tomorrow.

I had to bail out of the office late this morning to get back home while I could and I'll be land-locked for a couple of days due to local flooding southwest of St Louis. On my way out, I grabbed all (hopefully) my gear to set up my backyard impromptu test range along with a number of antennas. Once I get it set up and running, I'll be able to do relative gain and antenna pattern testing.

I happen to have a 2014 RCA 751R, a recently purchased WG7000, and I picked up both a new 7511 as well as an ANT705Z from a local Walmart on the way home. In total, I have about 18-20 different models to run through the process including a little gem that Santa brought me this winter, an AAronia BicoLOG-5070 (http://www.aaronia.com/products/antennas/BicoLOG-5070/) reference antenna that came complete with performance data. <grin>

Hopefully I grabbed everything I need....

OTAFAN
2-May-2017, 12:41 AM
Thanks for posting further testing results rabbit73! Very interesting indeed.

My amateur sense and experience with the RCA751 here at my location, and the nearly 5000 posts on Amazon from users all over the country have indicated its good to excellent performance in a variety of terrain. When RCA removed several elements from their new 7511, especially the UHF Tetrapole and VHF LPDA (I hope I wrote correctly here?), even a dummy like me could figure there would be a compromise in performance.

But what is surprising is how good the GE Indoor/Attic performed in your location, compared to both the RCAs. The GE is getting good reviews on Amazon. And I see they now have an outdoor version of the same antenna. It might be worth further investigation???

I'll be very interested in ADTechs findings when he posts them too. I feel like I'm back in school and really enjoying both you "professor's" lectures!! I'm doing a lot of homework, but ever learning. Thanks to you both again for sticking with this thread!

rabbit73
2-May-2017, 1:45 AM
And I see they now have an outdoor version of the same antenna. It might be worth further investigation???Thanks; I didn't know about that. Is it the GE 29884 Pro Outdoor/Attic Mount Antenna? Click on Outdoor 70 mile version:

https://www.amazon.com/GE-33692-Attic-Mount-Antenna/dp/B00DNJZ58M?th=1

http://forum.tvfool.com/attachment.php?attachmentid=2638&stc=1&d=1493690763
But what is surprising is how good the GE Indoor/Attic performed in your location, compared to both the RCAs.My guess is the reflector design helps the UHF gain a lot. The directors look like director pairs as in the Winegard patent. But, I haven't figured out the driven element that looks like a long dipole instead of a tetrapole or how the UHF yagi and the VHF dipole are combined. I'm not quite ready to open it up to find out, but the urge is getting very strong.

Please keep in mind what I said above. My measurements indicate how the antennas performed at my location, but they might not be a reliable indicator of the actual gain of the antennas.
I feel like I'm back in school and really enjoying both you "professor's" lectures!! I'm doing a lot of homework, but ever learning.This "professor" is still learning too, even after 76 years of antenna experiments.

OTAFAN
2-May-2017, 2:03 AM
Yes, your link to the GE Outdoor Antenna is right. There is also a review of it on You Tube posted sometime in early March of this year. I don't have it in front of me, but I'm sure you could find it on their website. I watched it a couple of weeks ago and it was interesting. The few reviews of it on Amazon so far, are promising.

Adtech mentioned the RCA ANT705Z. It looks very much like the GE Outdoor. Walmart has it on their web site. I'll be interested to see what his evaluation of it is.

If you decide to open your GE Indoor up and discover its mysteries, I'll be interest, rabbit73.

Yes indeed, I'm hooked on OTA TV and radio!

Anxious for the professor's next lectures!!

rabbit73
2-May-2017, 2:37 AM
Found the 29884 video; thanks.
https://www.youtube.com/watch?v=R_XAO14gSms

JoeAZ
2-May-2017, 5:40 PM
The G.E. 29884 Pro Outdoor/Attic Mount Antenna looks promising
but all that plastic........is cause for concern. With our intense
sunshine and 120f degree heat, I can visualize that plastic falling
apart, cracking and warping after a year or two of service.
A similar antenna, available at Walmart.com uses far less plastic,
and costs a bit less. Cannot help but wonder how it would perform
versus some of the other antennas, including the G.E. 29884.

https://www.walmart.com/ip/RCA-Attic-Outdoor-Compact-HD-Antenna/146879296

rabbit73
5-May-2017, 5:30 PM
If you decide to open your GE Indoor up and discover its mysteries, I'll be interest, rabbit73.Well, here it is:

http://forum.tvfool.com/attachment.php?attachmentid=2639&stc=1&d=1494003938

http://forum.tvfool.com/attachment.php?attachmentid=2640&stc=1&d=1494003938

I have used the conventional terms for top and bottom of the board. The top is where the components are mounted and the bottom is where the ground plane is located. In actual use, the coax connector faces down.

The GE 34792 Attic Antenna includes a REAL UVSJ, not shorting stubs, to keep the UHF and VHF signals separated before combining. Each section of the antenna has its own balun. The UVSJ and the well designed reflector are responsible for the good performance of this antenna.

Here is a circuit of a UVSJ by SM0HX (amateur radio callsign for a ham in Sweden). The UVSJ UHF/VHF Separator-Joiner belongs to the filter family of Diplexers. All UVSJs are Diplexers, but not all Diplexers are UVSJs; Diplexer is the more general term. A HLSJ is also a Diplexer, but for VHF-Low and VHF-High.

http://forum.tvfool.com/attachment.php?attachmentid=2641&stc=1&d=1494003938

The UHF highpass filter section has 3 series capacitors and 2 shunt inductors. The VHF lowpass filter section has 3 series inductors and 2 shunt capacitors.

Here are the curves for the Radio Shack UVSJ:

http://forum.tvfool.com/attachment.php?attachmentid=2642&stc=1&d=1494006989

OTAFAN
5-May-2017, 7:47 PM
Fascinating classroom lecture today, Professor rabbit73!

I've written down your "experiential fix" of the stripped screw for future use when necessary. Thanks for the tip!

Now I'm beginning to see how the mysteries of antenna theory work in real time from your analysis. Still I'm a bit awe struck, to say the least.

It will be interesting to see Adtech's field testing of GEs latest antennas in comparison to the similar RCA (AKA ANT705Z) that JOEAZ mentioned in his post. IMHO, the plastic used on both these antennas and similar others probably are UV resistant and will give at least a few years of use even in harsh desert environments. But mileage may vary in each individual situation.

I'm guessing that other antennas on the market today which are using built in baluns like this GE 34792 are of similar circuit design. This should be informative for those who end up using them at their locations, or who might have to open the board up in case possible circuitry issues. Your provided information has been very helpful here.

Thanks, as always, Professor rabbit73 for your yeomans efforts! Much appreciated!!

rabbit73
20-May-2017, 6:30 PM
The tests that I have made so far tell how well the antennas work indoors with my signals, but I have been searching for a test method that would give a more accurate indication of relative antenna gain.

I have settled on an Antennas Direct DB2E antenna and a Blonder Tongue HAVM-1UA Frequency Agile Modulator for a stable transmitted test signal.

I read about the antenna test measurements done by Kent Britain (WA5VJB). He has made measurements with the test antennas at ground level and above ground level. When the antennas are elevated, the receiving antenna picks up the direct signal and a signal reflected from the ground. I tried it both ways. The ground level signals level are much weaker, but the gain difference between antennas is about the same, so I used elevated antenna measurements. Kent was making measurements at microwave frequencies with horn antennas, see p. 5:
http://www.wa5vjb.com/references/Antenna%20Measuring%20Notes-keb.pdf

http://forum.tvfool.com/attachment.php?attachmentid=2661&stc=1&d=1495302313

http://forum.tvfool.com/attachment.php?attachmentid=2662&stc=1&d=1495302313

First I did a comparison between the antennas elevated on tables and on the floor. The HAVM is only for UHF:

Comparison between antennas on tables and antennas
on the floor for gain comparison measurements.

TABLES FLOOR

Channel GE PRO GE Attic GE PRO GE Attic
29884 34792 29884 34792
dBmV dBmV dBmV dBmV
15 -11.1 -13.4 -20.3 -22.3
28 -10.0 -9.8 -24.9 -23.4
39 -12.1 -12.7 -23.5 -24.2

OTAFAN
20-May-2017, 10:06 PM
Rabbit73, we really do owe you overtime wages for your continued testing results in this thread! Retired or not, I sure respect your life long experience in this technical field of TV antennas, et al. I'm back in your class sitting in the front row, no less.

And I wish there was some way we could repay you for all your very kind help on TV Fool. Like the best of my past teachers, you not only teach us students through narrative, but "show" us exactly what you're talking about with pictures, or rather, photos.

I just wish there was some way I could have say, Antennas Direct for example, send you an antenna or supplies of your choosing if I called them and placed the order. As long as they had a secure address I'd be willing to step up to the bar and pay the tab. LOL!

Anyway, it looks like the GE Outdoor has the edge with your testing so far. Interesting. And the AD DB2E looks like a very good antenna which could rival the GEs. With the VHF add on kit from AD, I'm toying with the possiblity buying one to see how well it would pick up signals in my area. Hmmm.....

Well, your loyal student is ready for his next lesson professor! Thanks so much again! BTW, very interesting article you linked from Kent Britain (WA5VJB). I have not heard about him before, but you can always count on the hams to come through!

rabbit73
21-May-2017, 12:28 AM
Kent writes an antenna column for CQ Magazine (amateur radio). He is the creator of the "Cheap Yagi" antenna. If you Google it:
https://www.google.com/#q=cheap+yagi&spf=1495326554715

This is his website:
http://www.wa5vjb.com/index.html

He did a version for TV reception:
http://www.wa5vjb.com/references/CheapYagi4HDTV.pdf

If you look at Figure 6 of that article, you will see an analog TV signal. That is what my HAVM modulator puts out. I am using the video carrier as a test signal.

OTAFAN
21-May-2017, 12:58 AM
OMG, rabbit73!

I'm just a kid in a candy store!

Now, to the homework.....circuit board antennas.....easy build it yourself yagis.....I'm down with it for the rest of the weekend.....:) P.S. I'm fascinated by your test equipment!

rabbit73
21-May-2017, 1:24 AM
The next test that I did was to compare the GE PRO, ANT 751R, and the ANT 7511.

Relative Gain Comparison of three Antennas

Channel GE PRO RCA RCA
29884 ANT751R ANT7511
dBmV dBmV dBmV

15 -10.2 -12.5 -15.6
28 -10.4 -11.6 -13.4
39 -12.0 -12.3 -16.3

Equipment Used:
Antennas Direct DB2E source antenna
3 antennas to be compared
Blonder Tongue HAVM-1UA Agile Modulator
20 dB attenuator to reduce HAVM output
Sadelco DisplayMax 800 Signal Level Meter

Test Conditions:
Indoor Test Range; ground floor, carpet over concrete slab
Antennas 10 wavelengths apart
Antennas elevated on Table-Mate tables
Signal Level Meter measuring analog video carrier

Conclusions:

The GE PRO 29884 antenna is the best of the 3 antennas for my indoor location. The RCA ANT 751R is a close second. The RCA ANT 7511 is third. The RCA design change has sacrificed considerable UHF gain.

I have a little more confidence in these measurements, but there are reflections that will introduce errors. I miss my outdoor range with stable LOS signals.

I'm fascinated by your test equipment!So am I. Making antenna measurements is one of my favorite things.

You don't need a lot of expensive equipment. With just a variable attenuator and a TV, you can measure margin to dropout of the signal. The simplified form is shown in my signature link.

http://forum.tvfool.com/attachment.php?attachmentid=2405&d=1477146996

OTAFAN
21-May-2017, 2:14 AM
I too, wish you still had your outdoor set up rabbit73. But your most recent test results probably would be similar out of doors, is my amateur guess.

Still, what you have shown here on this thread with the indoor equipment used, more than justifies my nomination of you as, THE DEAN OF TV FOOL.

And you just cannot take away certain vital elements in a TV antenna as RCA has done with their stripped down version 7511, without compromising overall gain. I'm fairly certain someone with a good understanding of physics, math and electronics would agree with me??? I'm still in undergraduate school as far as those subjects go.

But as far as everyday reception goes, RCA dropped the ball on a very good antenna with their newest version 7511. Fortunately, us OTA fans out here in the hinterlands have other choices going forward. And your help with this issue has been exceptional, rabbit73! THANK YOU!!

ADTech
23-May-2017, 9:07 PM
I finally should be able to upload a summary plot of the relative boresite reception of a number of small Yagi/LPDA antennas from my testing earlier this month.

A few notes to ponder while you're waiting:

1. I'm not terribly happy with the quality of the data gathered. I identified, after the fact, a number of things that need improvement in my process including an huge signal "suck-out" (it will be painfully obvious) in the middle of the UHF band, probably due to an unwanted signal reflection or a fault with a cable or the transmitting antenna. I didn't find it until the range was broken down and I started pulling data into Excel for plotting. Since the anomaly is present for all of the antennas tested, it's still an equal playing field.

2. I did not have the opportunity to normalize the spectrum analyzer to the tracking generator (impractical), either before each measurement was made or via a correction file in the post-processing (didn't think of it) in order to smooth tracking generator non-linearities (up to +/- 2dB over sweep span) and other fast-changing (frequency-wise) impairments. If you know how to easily implement weighted average smoothing in Excel 2007, I'd be interested.... It would really clean up the presentation of the data.

The plot to be posted, once I finish tweaking it in the morning, is fairly congested with the data for seven antennas overlaid using Excel's default coloring scheme (ugh!). I haven't gotten around to changing the line style and color for better legibility and probably won't since this plot is a one-off from my normal analysis which normally compares ten different readings for each antenna done in a two-up comparison (Antenna A vs Antenna B).

I will say there are some interesting results to be seen. ;)

OTAFAN
23-May-2017, 9:50 PM
Thanks for sticking with this thread, ADTech!

Even though your testing is not under optimal conditions and rabbit73s too, both of you are probably doing ground breaking research here. I have found very little results for these type of antennas anywhere on the Net. Perhaps there are posts somewhere, but I have not seen any. If someone reading this thread can illuminate us here, I would certainly appreciate it.

Anyway, anxious for your test results ADTech!:)

rabbit73
24-May-2017, 1:17 AM
I did one final test in this indoor series, which is to compare the GE Attic Antenna with the AD DB2E, using the GE Pro as a source antenna.

Comparison of GE Attic Antenna with Antennas Direct DB2E

Channel GE Attic AD
34792 DB2E
dBmV dBmV

15 -15.4 -11.4
28 -12.2 -11.0
39 -15.4 -12.3

Equipment Used:
GE PRO 29884 source antenna
2 antennas to be compared
Blonder Tongue HAVM-1UA Agile Modulator
20 dB attenuator to reduce HAVM output
Sadelco DisplayMax 800 Signal Level Meter

Test Conditions:
Indoor Test Range; ground floor, carpet over concrete slab
Antennas 10 wavelengths apart
Antennas elevated on Table-Mate tables
Signal Level Meter measuring analog video carrier

The Antennas Direct DB2E wins.

OTAFAN
24-May-2017, 1:47 AM
Thank you, Dean rabbit73!

Looks like AD DB2E more sensitive or gain than GE Attic on UHF channels you tested. Of course, you would have to add a VHF kit to use as all around antenna, whereas GE already equipped with VHF dipole. Also, cost comparison, GE is less. Something to certainly consider.

I can only speak for me, but all your testing here as educated me immensely in what to look for in good antenna reception. I cannot thank you enough for the information. As I previously mentioned, not much out there to judge these antennas nowadays.

rabbit73
24-May-2017, 2:08 AM
Also, cost comparison, GE is less.Not much difference; the DB2E was on sale.
http://www.solidsignal.com/pview.asp?p=db2-e&d=antennas-direct-db2-e-db2e-multi-directional-bowtie-uhf-dtv-antenna-(db2-e)&sku=853748001408

Of course, you would have to add a VHF kit to use as all around antenna, whereas GE already equipped with VHF dipole.Yes, you are correct.

That is my next project; channel 13 ABC is weaker because the folded dipole doesn't have much gain, and a reflector is needed for VHF because of multipath reflections.

It will be difficult because VHF-High antennas are about 3x the size of UHF antennas.

OTAFAN
24-May-2017, 3:32 AM
That's a very tempting price.....sold I think!

I would be interested in your VHF findings when you're able to post, professor rabbit73.

Thanks!

ADTech
24-May-2017, 4:01 PM
As promised yesterday, I've attached the mentioned plot.

A couple of additional notes:

1) I added black vertical lines to denote the boundaries of the current high HF and UHF bands.

2) Low VHF reception was not a factor in this data collection effort.

3) The RCA751R was purchased at a local Menard's in late 2015.

4) The RCA 7511 and 705Z were purchased from a local Walmart less than a month ago.

5) The Winegard HD7000R was purchased from an online seller this spring. It is the newest (known) version that includes the low-VHF conversion kit which was not installed for this testing.

6. The GE 30741 was purchased about a year ago at a local Walmart.

7. The CM3010 was purchased directly from CM's web store last summer. COMMENT: This antenna fared so poorly against the rest of the pack that I suspect that it may have a faulty balun. The alternative interpretation is obvious.

8. The identical physical layout, cabling, test equipment configuration, and data collection procedures were used for each antenna to the best of my knowledge and ability.

9. Boresite reception as a basis for a relative antenna performance comparison is only one of the possible tests that can be performed to characterize any given antenna. Polar patterns are probably a more instructive characterization as they identify the additional parameters of F/B ratio, F/R ratio, beam width, as well as major and minor lobes, if any. They are not included in this posting for various reasons including several deficiencies that I identified post-testing and I'd prefer not to have to address.

http://forum.tvfool.com/attachment.php?attachmentid=2664&d=1495639678

Observations:

By virtue of it's UHF reflectors, the RCA705Z offered the best UHF performance of this cohort. It's VHF performance, however, was hindered by its single folded dipole element when compared to its stablemates. Now, if they tacked that UHF front end onto the VHF section of the 75XX, it would be an interesting combo for close-in work. It also probably would not end up on the shelf at Walmart due to the resulting larger package size, IMHO.

The other two RCAs and the WG (all three are manufactured by WG) are based on the same original design and are all very similar in performance with some observable minor differences. FWIW, it would be my opinion that the casual antenna user would probably never note any difference unless they happened to be right on the edge of reception for a station using a channel where a difference in reception can be discerned from the attached plot. YMMV.

If I think of more comments later, I will append them below this line.

Cheers!

JoeAZ
24-May-2017, 5:01 PM
Wondering what kind of polarization did you use? How much of a factor
would the polarization play in your tests??

ADTech
24-May-2017, 6:12 PM
Wondering what kind of polarization did you use? Everything (TX & RX antennas) was horizontally polarized since that is the de-facto standard for North American TV broadcasting as well as the design of all of the tested antennas. I could just as readily, with a bit of hardware modification, have rotated everything 90° but it would have had little to no impact on the recorded results except possibly for ground reflection influence.

How much of a factor would the polarization play in your tests?? Not sure what detail you're inquiring about, but I can say that from prior experience, that if I cross-polarize one of the antennas, there's usually a penalty of 20 dB or more.

JoeAZ
24-May-2017, 7:28 PM
I asked because one of the translators we view uses circular polarization,
I have been told. Supposedly, circular polarization is somewhat better
with mountains and hills. That translator is most always a challenge to
receive over all the others.

OTAFAN
25-May-2017, 6:34 AM
Wow, VERY INTERESTING results ADTech!

I'm still pondering your graph. But I do have a question first before proceeding with perhaps a few other comments.

Is there a way to figure out the overall gain of the antennas you tested for their VHF High/UHF and FB numbers? Sometimes on various antenna web sites you will see numbers like 5/7 for VHF/UHF gain and 12 FB. Perhaps a mathematical formula or even something less technical? Pardon me if I'm not asking the question in the correct way. I'm still very much learning about the technical side of TV antenna reception. But TV Fool has really helped me in this regard.

Thanks so much again for your results. This will be quite useful for me in evaluating possible future antenna purchases.

Tower Guy
25-May-2017, 1:52 PM
In my opinion circular polarization is worse with mountains than H pol only. This is because the V pol reflects more than the Hpol. This multipath is the bane of 8VSB.

ATSC 3.0 will do better with multipath and circular polarization than 8 VSB.

ADTech
25-May-2017, 2:17 PM
I asked because one of the translators we view uses circular polarization, I have been told. Supposedly, circular polarization is somewhat better with mountains and hills. That translator is most always a challenge to receive over all the others.

I've never heard of CP or EP being useful for that purpose. I've always heard that it helped with indoor antennas or mobile-type reception devices (which didn't pan out under ATSC 1.0).

What are the call letters of that translator?

Edit: I see TG chimed in while I was typing. His perspective on that subject should carry more weight since he works on the transmit side of the broadcast system.

ADTech
25-May-2017, 3:12 PM
Is there a way to figure out the overall gain of the antennas you tested for their VHF High/UHF With the data as previously presented, no. The comparable data from a reference antenna of known characteristics would need to have been included so that the mathematical comparisons could be done. See image and discussion following.

...and FB numbersF/B ratio could be measured by performing the same set of measurements with AUT aimed 180° opposite boresite. I didn't make that particular measurement using the linear frequency sweep procedure plotted above although I did do 360° rotational patterns which would discern this behavior though for specific frequency cuts.

Here's a sample that compares the RCA7511 to our clip-on VHF module which is tuned to 195 MHz, the center of the high-VHF band. See notes following.

http://forum.tvfool.com/attachment.php?attachmentid=2665&stc=1&d=1495723497

Notes:
1) A hardware failure in my circuit that synchronizes the SA sweep to the rotor's start of rotation forced me to manually trigger the SA sweep using a manually activated micro-switch in conjunction with activating the rotor. Consequently, the data may be easily skewed by as much as a second or two (7.5-15 degrees). Kindly overlook this shortcoming, it's particularly noticeable in the 7511's pattern.
2) The data was normalized so that the maximum point in the paired data set was set to "0" and the rest of the data was adjusted by the same amount for the purposes of this comparison. Using Excel, there are, of course, a good number of possible data display methods possible, this happens to be the one I chose as I attempt to enhance my feeble Excel and VBA skills. ;)
3) The VHF module, if balun and insertion loss adjustments were included (they aren't at this point) would be about as close to a reference dipole as a no-budget measurement effort could produce. I may explore this later and then compare it to the BicoLOG just to see how close they are to each other. In the meantime, I'd assume a 1 dB insertion loss @195 MHz and that will get you better than in the ballpark (probably into the infield) for an estimate.
4) Using the above described F/B definition, the F/B of the dipole is measured a almost zero, the 7511 is measured at about 15 dB.
5) Using the above described gain definition and including the estimated insertion losses, I'd estimate that the forward gain of this antenna, as tested, is ~ 5 dBd (7.15 dBi) at 195 MHz.

JoeAZ
25-May-2017, 5:02 PM
I spoke to an engineer for Arizona PBS, KAET, several years ago
while at the summit of Mingus Mtn. I mentioned that his
translator, K42AC, was harder to receive than the others on
Mingus. He told me that the signal was directed away from
Prescott and Prescott Valley and that they were using
circular polarization. He then told me to tilt the 4 Bay antennas
from an "X" to a "+" which he said would help. It did help
but not much..... It continues to be hard to receive through
much of the area.

ADTech
25-May-2017, 6:45 PM
K42AC shares a Jampro JA/LS-8 with K38AI and K40DD up on Mingus Mtn and the antenna is H-POL only, none of them are licensed for any vertical component in their signal. Their antenna is, however, highly directional to the east-northeast with a good amount of electrical down tilt (3°). K42AC, however, maxes out at only 5 KW ERP along its maximum strength signal path compared to 12-15 KW for the other two stations on the antenna. The worst case, if one were situated in one of the weakest nulls, would be that only 920 watts might be sent in that direction. By contrast, K38AI peaks out at 15 kW with a minimum of 2.65 KW in its deepest null.

I suspect the much lower ERP and the directional antenna are the root cause for the difficulty in receiving K42AC as compared with its neighbors, depending o the relative direction and distance of the receiving location relative to Mingus Mtn. The weaker UHF signal of K42AC will be much less capable of diffracting to lower elevations where terrain is an issue or even for simple longer distance locations, even with LOS.

My interpretation, based on the antenna patterns and the City of License for each facility, is that KAET intends K42AC to cover the Cottonwood side of Mingus Mtn and for K43LW, located on Mt Francis, to cover the Prescott side.

Tower Guy
25-May-2017, 7:04 PM
That translator is most always a challenge to
receive over all the others.

K42AC is located on the Northeast side of the mountain with a short tower that doesn't see over the peak. Prescott is Southwest of the transmitter. There are shadows and weak signals in Prescott.
http://www.tvfool.com/?option=com_wrapper&Itemid=80&q=call%3dK42ac

The use of circular polarization may not play a role with your spotty reception of K42AC.

JoeAZ
25-May-2017, 10:53 PM
My interpretation, based on the antenna patterns and the City of License for each facility, is that KAET intends K42AC to cover the Cottonwood side of Mingus Mtn and for K43LW, located on Mt Francis, to cover the Prescott side.

Unfortunately, K43LW on Mt Francis, is only 1kw and is severely
hampered by the hills and terrain of Prescott. Additionally, there
is another RF43 on Bill Willaims Mtn about 40 miles away. Many areas
have LOS to Mingus and Williams but not Mt. Francis. That is why it
is imperative to capture K42AC. There is another PBS translator in
Flagstaff on RF14 but it cannot be received because there is also a
translator for KUTP, RF 14 on Mt Francis, here in Prescott.
It is what you could call " A MESS."

JoeAZ
25-May-2017, 10:55 PM
K42AC is located on the Northeast side of the mountain with a short tower that doesn't see over the peak. Prescott is Southwest of the transmitter. There are shadows and weak signals in Prescott.
http://www.tvfool.com/?option=com_wrapper&Itemid=80&q=call%3dK42ac

The use of circular polarization may not play a role with your spotty reception of K42AC.

I cannot help but wonder if the polarization was changed, if the F.C.C.
database is correct or if the engineer was mistaken.

Tower Guy
26-May-2017, 12:34 AM
I cannot help but wonder if the polarization was changed, if the F.C.C. database is correct or if the engineer was mistaken.

I'd guess that the engineer was wrong. Perhaps he was thinking about a different facility. The Jampro antenna listed is Hpol only. The FCC application does not mention a CP antenna.

The ability to pick up a signal while your antenna was mounted vertically indicates significant depolarization due to refraction off the mountains.

In mountainous locations antenna height can make a huge difference. You can try moving your antenna up or down to see if reception improves. Scientifically, you can calculate the angle to to the mountain, determine the slope in front of the antenna, and use ray tracing techniques to get a good starting point. I don't know where you live in Prescott, but you may find that an antenna several feet off the ground with nothing in front of the antenna might be better than the roof.

ADTech
26-May-2017, 11:21 AM
I'm going to go with the engineer either mis-poke or there was a miscommunication. There's nothing in the FCC file that indicates the digital facility was ever anything but what it still is.

It is what you could call " A MESS." I'd expect it's going to get a lot messier as the repack progresses. All of the facilities operating on channel 38 and above must vacate those channels. And, since none of the translators (and other LP-class stations) are even guaranteed a post-repack channel, it's fairly likely that some will disappear completely and that the remaining ones get packed even tighter into the remaining channels, increasing the rate of co-channel and adjacent channel interference. Since this class of operator does not enjoy any interference protection under the rules, the mess will not get better.

JoeAZ
26-May-2017, 4:56 PM
[QUOTE=
In mountainous locations antenna height can make a huge difference. You can try moving your antenna up or down to see if reception improves. Scientifically, you can calculate the angle to to the mountain, determine the slope in front of the antenna, and use ray tracing techniques to get a good starting point. I don't know where you live in Prescott, but you may find that an antenna several feet off the ground with nothing in front of the antenna might be better than the roof.[/QUOTE]

Agreed. In some locations I've lost RF13 but received RF22 which
transmit from the same basic location. Moving the antenna a few feet,
I was able to capture RF13, though weakly.

JoeAZ
26-May-2017, 5:02 PM
I'd expect it's going to get a lot messier as the repack progresses. All of the facilities operating on channel 38 and above must vacate those channels. And, since none of the translators (and other LP-class stations) are even guaranteed a post-repack channel, it's fairly likely that some will disappear completely and that the remaining ones get packed even tighter into the remaining channels, increasing the rate of co-channel and adjacent channel interference. Since this class of operator does not enjoy any interference protection under the rules, the mess will not get better.

Agreed. I've done some studies and found that in almost every case,
low band VHF will be used. There will be even more co-channel interference.
Invariably, some channels will simply disappear. Trying to find as compact
as possible antenna capable of RF 2-36 or Rf 2-51 is impossible.....

ADTech
26-May-2017, 11:09 PM
Trying to find as compact
as possible antenna capable of RF 2-36 or Rf 2-51 is impossible..... That's because of the physics of the lower frequencies. You can currently get a small Winegard (HD7000R) or a small Channel Master like the CM3016 or CM5016 but they're going to range from rudimentary like the HD7000R or fairly modest for the CM models which are still fairly large (relatively).

Personally, I'd expect the rural translator operators to do like all the majors and avoid low-VHF for the most part unless there's nothing less to pick from. IIRC, the filing window for the LP and translators being displaced is later this year so we'll have to see how it shakes out.

rabbit73
28-May-2017, 1:27 AM
ADTech
I bought two EU385CF for evaluation. I opened the black enclosure, and something didn't look right. I opened the second enclosure and it did look right.

I was able to figure it out, but if someone only purchased sample #1 with the upside down label, it might confuse them.

Sample #1 was sealed at the rear with epoxy; sample #2 with solder and epoxy, so I didn't mess with it.

Since you do QC, I thought you should know. I also called customer service to let them know, but didn't ask for an RMA because I wanted to look inside anyway to add to the AVS UVSJ thread.
http://www.avsforum.com/forum/25-hdtv-technical/1036829-best-uhf-vhf-combiner-8.html

my post for the Antennas Direct EU385CF-1S UHF/VHF Diplexer (UVSJ):
http://www.avsforum.com/forum/25-hdtv-technical/1036829-best-uhf-vhf-combiner-8.html#post53267506

ADTech
31-May-2017, 2:47 PM
Thanks for bringing that to my attention. Must have been a Monday morning at the factory!

I couldn't find any relevant tickets in our system. Any chance you received a ticket number?

rabbit73
31-May-2017, 7:13 PM
Sending ticket number in a PM on other forum.

rabbit73
6-Jun-2017, 1:41 AM
That's a very tempting price.....sold I think!

I would be interested in your VHF findings when you're able to post, professor rabbit73.

Thanks!I did some more testing with my GE 34792 Attic Antenna indoors on VHF-High because CH 13 is more difficult to receive than my UHF channels.

I found a convenient location in the bedroom for the antenna and made some measurements. In this location, CH 13 is picked up by the tuner, but there is picture freeze and many uncorrected errors, not too good:

http://forum.tvfool.com/attachment.php?attachmentid=2681&stc=1&d=1496712910

The signal level meter shows adequate signal strength, but a bad channel scan:

http://forum.tvfool.com/attachment.php?attachmentid=2682&stc=1&d=1496713140

rabbit73
6-Jun-2017, 1:59 AM
I suspected that multipath reflections were causing a problem and decided to add a reflector element to the VHF folded dipole. A cardboard box is used as a temporary support.

http://forum.tvfool.com/attachment.php?attachmentid=2683&stc=1&d=1496713473

The reflector is 13" behind the VHF dipole and consists of a 24" length of 1" aluminum tubing with a 12" length of 7/8" tubing in each end and clamps. The length has been adjusted to 27.7". I also tried a strip of aluminum foil on a yardstick with the same results:

http://forum.tvfool.com/attachment.php?attachmentid=2684&stc=1&d=1496713915

The reflector improves the reception:

http://forum.tvfool.com/attachment.php?attachmentid=2685&stc=1&d=1496714072

and the scan looks a lot better:

http://forum.tvfool.com/attachment.php?attachmentid=2686&stc=1&d=1496714197

rabbit73
6-Jun-2017, 2:18 AM
Since the convenient location for the antenna had some problems, I tried other locations in the room. The best location for the signal was in the middle of the room in a high traffic area (of course it was).

http://forum.tvfool.com/attachment.php?attachmentid=2687&stc=1&d=1496715021

No reflector was needed in this location and the reception was excellent:

http://forum.tvfool.com/attachment.php?attachmentid=2688&stc=1&d=1496715151

and the channel scan looks good, with increased signal strength:

http://forum.tvfool.com/attachment.php?attachmentid=2689&stc=1&d=1496715270

rabbit73
6-Jun-2017, 2:29 AM
The Sadelco DislayMax 800 signal level meter makes 43 measurements across the channel and diplays the average of all readings. If one of the 43 measurements is below -20 dBmV, the meter says "Ur" for under range and doesn't give a reading. The scan covers about 5.3 MHz of the 6 MHz channel.

http://forum.tvfool.com/attachment.php?attachmentid=2691&stc=1&d=1496716036

If the meter is switched to the single frequency mode, it will measure down to -35 dBmV at the center of the channel, but the correction for a digital signal is not added; +6.8 dB IIRC.

http://forum.tvfool.com/attachment.php?attachmentid=2692&stc=1&d=1496761421http://

The screen on the meter actually shows a dark gray image on a dark green background and doesn't have much contrast. The image looks pretty good on a computer screen, but makes a muddy image on a print.

analog channel:

http://forum.tvfool.com/attachment.php?attachmentid=2693&stc=1&d=1496762257

digital channel:

http://forum.tvfool.com/attachment.php?attachmentid=2694&stc=1&d=1496762257

To make an image that has more contrast and room for notes, I set my digital camera for a B&W image, and then edit in Photo Gallery to increase the contrast.

http://forum.tvfool.com/attachment.php?attachmentid=2695&stc=1&d=1496769065

Photo Gallery will only allow me to increase the contrast one time, AFAIK, so I use Lunapic to increase the contrast 4x more:

http://forum.tvfool.com/attachment.php?attachmentid=2689&d=1496715329

OTAFAN
6-Jun-2017, 4:00 AM
You may not have your outdoor antenna testing equipment available anymore, rabbit73, but your indoor results here are AMAZING!

As I'm beginning to understand much better now, indoor antenna set ups are even more complex and perhaps mysterious than their outdoor counterparts. LOS is a bit more straight forward out of doors, or so it seems. But like you previously mentioned, not everybody can put up an outdoor antenna.

If you keep up grading that GE Indoor antenna of yours, you might want to seek a patent, make a ton of money and really retire in a manner you're unaccustomed too--LOL! But necessity is the mother of invention. I'm copying your attachments for possible future inventive use. Ha! Ha!

Thanks for remembering my request here, rabbit73! I appreciate your dedication to this forum. It has been extremely enlightening. BTW, I've been watching your other posts. I'm learning something new every day!

rabbit73
6-Jun-2017, 1:23 PM
Thank you for your encouraging comments. I also learned a lot about indoor reception from this experiment.

Trip in VA, who runs the rabbitears.info web site and now works for the FCC, had an even more difficult time with reception of local signals. When he was living in Chattanooga he had to put his antenna inside a trash can to reject multipath reflections.

http://forum.tvfool.com/attachment.php?attachmentid=2203&d=1470521359

Background information on this technique:

http://www.avsforum.com/forum/25-hdtv-technical/1372416-chattanooga-tn-got-atlanta-but-few-locals-2.html#post21358820

http://forum.tvfool.com/showpost.php?p=50727&postcount=7

OTAFAN
25-Jun-2017, 3:14 AM
[QUOTE=rabbit73;57752]One secret is that the UHF driven element is a tetrapole, in the original version of the 751.

I have another question regarding the tetrapole on the RCA751 as to how it would correspond to an LPDA antenna such as AD Element.

I think I understand better now how it works on the 751, but how does an LPDA separate and combine UHF/VHF signals?

I have reread a Wikipedia article on the LPDA and it seems to me that it may have something to do with the fact that the dipoles are electrically connected directly into the boom(s) rather than the cross phased elements in the 751. But being the very much the amateur that I am in this field TV antenna electronics, I'm at a loss for a rather simple understanding. And since I'm considering adding an LPDA at my location, this would be very helpful.

Thanks again in advance for your kind help!

rabbit73
25-Jun-2017, 3:04 PM
http://forum.tvfool.com/attachment.php?attachmentid=2761&stc=1&d=1498402788

I have another question regarding the tetrapole on the RCA751 as to how it would correspond to an LPDA antenna such as AD Element.

I think I understand better now how it works on the 751, but how does an LPDA separate and combine UHF/VHF signals?The Tetrapole on the RCA ANT751R has two functions. First, it is the driven element (DE) for UHF signals. Second, it acts as a UHF/VHF combiner (UVSJ) in conjunction with the shorting stubs. There is no need for a UVSJ on the AD Element Antenna; it is designed for continuous coverage of UHF and VHF-High. What is curious is that a UVSJ is suggested as an accessory for the Element on the AD site. It would be useful if you only wanted to use the Element for VHF-High and have a separate UHF antenna.
I have reread a Wikipedia article on the LPDA and it seems to me that it may have something to do with the fact that the dipoles are electrically connected directly into the boom(s) rather than the cross phased elements in the 751.The LPDA can be constructed either way. It can have two booms that are insulated from each other that also act as phasing lines to connect the elements together, or it can have one boom with the elements mounted on insulators and wires to connect the elements together. The two ways are electrically equivalent, but physically different.

kennylive
4-Oct-2017, 11:01 PM
My guess is they didn't want to pay Denny's Antenna Service the licencing fee anymore.

Denny's has good stuff, but it's hard to pay $70 for his antenna, when you could buy it at Amazon or Menards for $40.

OTAFAN
6-Oct-2017, 10:31 PM
Hi kennylive: Yes, before I posted this thread here, I emailed Denny's Antenna with a question about the RCA751, or rather his version of it, but he never replied back.

So I posted my question(s) here on TV Fool and received numerous replies and analysis, especially from rabbit73 who is very learned in this field of TV antenna electronics. I would encourage you to read as many of his threads as possible because you will learn a lot.

Anyway, stay tuned as they say because you usually clear reception for your issues here. Best, :)

kennylive
7-Oct-2017, 11:57 PM
I have seen Denny actually post on here, but he's pretty tight lipped about the gain is his antennas, and his arrangement with RCA. He plainly says he designed the EZ-HD and the Stacker with Winegard, and the 751R is exactly the same as the EZ-HD. Exactly.
Some years ago he commented that the 751 (no R) was a 7 through 69 antenna, but the EZ-HD had been re-tuned to 7 through 51, with improved gain. And then the 751R came out.
I really like his designs, but his prices are high, and it's a long way between the EZ-HD and the Stacker.

OTAFAN
8-Oct-2017, 1:09 AM
Well, not knowing his handle here on TV Fool, it would be easy for me to miss his postings, kennylive. I would have thought he might have been interested in chiming in on this thread. It would have been interesting and helpful to have his input.

Not sure why the all the hush-hush about the gain of the 751. I found a couple of postings on the Net of about a "5" gain front to back average for both VHF/UHF. I even asked RCA Tech on their website and they gave me answers about everything else I asked for, but nothing regarding gain. Maybe rabbit73 will have some information. Actually, I just remember AdTech did some field testing with interesting results on this thread regarding gain. Yes, I see looking back now he sure did. So, there you go.

Anyway, Denny does indeed have an interesting website but pricey as you say.

Thanks for the reply kennylive. I just wish Denny would have replied to my email to him. But I understand my RCA751 here much more than when I first put it up. Its proven itself across the country in various, but usually moderate to stronger signal areas. Price to performance is good and sales show it so. Too bad about its most recent revision. Not quite as good. But I'm sure you read through this thread about that issue.

gmcjetpilot
28-Apr-2018, 1:43 AM
The gain and polar pattern for the Winegard HD7000R can be found in solid signal dot com under product info tabs >Downloads>Download Product Manual. I post the primary info below....

The HD7000R is very similar to the ANT751 (almost identical to the revised ANT7511 with following exception). It has four aerial extensions you can add to the VHF section to add coverage Low-VHF. As stated the RCA ANT751 was made by Winegard. The HD7000HD has a single piece boom like the original ANT751 (but no longer it has been divided into two to make for a smaller shipping/retail package). The mast mount is not on very back end off the boom like the original ANT751 but forward of the last two VHF aerials (like I think the ANT7511 is).


Net Weight 2.36 lbs.
Active Elements 10
Boom Length 32.75
Turning Radius 52.2
Maximum Width 100" (with aerial extensions on for low VHF)
Vertical Height 3"
Element Diameter 3/8"

CHANNEL
CH.2, CH.4, CH.6, CH.7, CH.9, CH.11, CH.13, CH.14, CH.32, CH.50, CH.69
dB gain over reference dipole
0.2, 1.8, 0.5, 5, 5, 5.3, 4.1, 3.6, 5.1, 6, 6
beamwidth at half power points
83°, 82°, 78°, 51°, 66°, 48°, 33°, 75°, 54°, 40°, 43°
front-to-back ratio
1dB, 3dB, 8.5dB, 12dB, 12.5dB, 4.5dB, 7dB, 10.5dB, 14dB, 11dB

Polar Plots
Chan 2-5 it is a figure eight front to back. The back lobe gets slightly smaller going from Chan 2 to 6. This is a pure dipole pattern.

Chan 7-13 Typical Fwd gain lobe, Back side either 3, 2 or 0 small lobes. Ch 13 has some side gain and one medium back lobe.

Chan 14--51: Going from 14 to 51 there is primary Fwd lobe going from wide to diminishing width. On back side it goes from smaller and smaller dual lobes at 135 degree and 225 degree.

I think the gain is low but more than adequate for a "urban" antenna with stations w/I 30 miles. The original RCA751 should be slightly better. My understanding is the new RCA7511 lost a little performance.

My original RCA751 gets LP (7.5KW) stations 9 miles out. That is similar to getting a flame thrower station at 30 miles. I have some obstacle issues (ridge, trees, high roof lines) to deal with and my experience is only TESTING. I had it on my "test stand" 18 feet in the air near my backyard tree line. It's going further away from the trees and up to 40 feet above ground. As of now I was getting SNR of 21-32 on all stations, including the lower powered stations. I actually have TWO ANT751's, which I am stacking. I have a nearby PBS station which is about 100-110 degrees off the primary direction for all other stations. The RCA pretty much NULLS PBS despite being close. No matter how much I play with direction I can't get low powered stations (which I watch) and PBS. Stacking two and combining I got great results on all stations. The dual stack test at 18 feet AGL was a success. At 40 feet above ground, further away from trees, I should be golden. Will raise the mast next weekend I hope. I have a new rotor but will save that for a SWL loop antenna... Rotors are great but to be avoided.

OTAFAN
28-Apr-2018, 3:31 AM
I'm glad you found your way through this thread to TV Fool, gmcjetpilot!

And thank you very much for the informative post above! I will bookmark it for future reference.

Here in greater LA/OC SoCal, there is going to be more action on low VHF due to the repack. Currently, I'm still using the RCA751 as my main outdoor antenna, but I'm looking at my options going forward so I will be able to watch some channels on those frequencies. There is a couple of affordable RCA antennas currently, but I'm waiting to see if anyone else offers something else on the market. I'm sure it will depend upon monetary considerations. So, thanks for pointing out the HD7000.

Please post any further testing results as you mentioned above when you can. I would be really interested in your findings.

This is a wonderful forum with excellent help from many posters. I'm sure you'll find it as helpful as I have.

Best OTA TV viewing.....

P.S. I too have been a avid SW/AM listener.

Nascarken
28-Apr-2018, 10:57 AM
Hello OTAFAN if you are looking too buy an outdoor tv antenna and won't it too last a lifetime.I suggest the Winegrud 8200U it's the best of the best if you are looking too buy
a hi and low vhf/uhf ANTENNA out there for the money.And what is your tv Fool report
Card say becuse you might want too buy a channel master amp.the way how I look at it
If you are going too spend money on an ANTENNA sistom .don't be cheap about it BUY the
best and have no regrets only a happy OTAFAN!!well good luck and have a good day.

OTAFAN
28-Apr-2018, 7:54 PM
Thank you, Nascarken for the recommendation! Wineguard 8200U is certainly a premium antenna, from what I could see on their website.

But I live in a strong signal area and don't need that large of an antenna or preamp. My RCA751 delivers anywhere between 25 to 36(mostly above 30), SNR on my Samsung signal meter, for around 180 received channels in several different languages, no less. So, the 8200U might be too much for my situation. But the HD7000 might fit the bill since it's just a bit larger version of the 751, two longer dipoles for low VHF. If I need more gain, I found the RCA 3037XR, which has more UHF/high & low VHF elements to it, but not too much larger or heavier than my current set up.

As I mentioned to gmcjetpilot, I'm waiting to see if any other options for low VHF come up, but as Rabbit73 has mentioned several times, it just depends on if the manufacturer can make money on producing a new antenna. I'm curious to see if Antennas Direct is going to come up with a low VHF option???

Thanks so much again for your kind reply, Nascarken! I appreciate your input and if you can think of anything else, please post.

Best to you!

stephenson
2-Feb-2019, 6:08 PM
Even though this post is well after the thread was completed, I wanted to thank everyone who participated - especially rabbit.

I just cut Cox cable - they raised price three months after they guaranteed a price for a year - three months!

http://www.tvfool.com/?option=com_wrapper&Itemid=29&q=id%3d9038290b2ad724

The channels I really want are in the 20 mile range - especially PBS.

Attic mount - two options for ease and cost - both GE - 29884 and 36992 ... I like the 29884 as it looks a bit better build.

Thanks, again!

rabbit73
3-Feb-2019, 2:17 AM
Even though this post is well after the thread was completed, I wanted to thank everyone who participated - especially rabbit.Thank you for your kind words; you are welcome.

Attic mountThe signals in your report are very strong, but your report assumes your antenna will be outside and in the clear. However, since your antenna will be in the attic, the signals will be weaker. Aluminum siding and aluminum foil thermal barrier on the sheathing will block TV signals.
two options for ease and cost - both GE - 29884 and 36992 ... I like the 29884 as it looks a bit better build.The 29884 is more sturdy.

stephenson
3-Feb-2019, 1:25 PM
Thanks, rabbit.

Started to order from amazon, but got stuck on which RG 6 .... been awhile since I beat this topic to death.

LOTS of marketing on coax ...i’ve installed 1000s of feet, but never found a notable “difference” ... I’ve also installed a zillion feet of RG 59, but further, er, back in time. I’ve had issues with sloppy connectors (mine and others), but never enough cable line loss for me to tell something was wrong.

Have reviewed the line loss charts for 18 awg ... they don’t differentiate whether it is solid copper or copper clad steel ... any real difference or just marketing? (Steel a bit stiffer, but ...)

Any real preference between manufacturers for RG 6? I do always try to buy USA sourced.

Btw - any difference in net signal between screw on a crimp on connectors?

rabbit73
3-Feb-2019, 6:05 PM
Have reviewed the line loss charts for 18 awg ... they don’t differentiate whether it is solid copper or copper clad steel ... any real difference or just marketing? (Steel a bit stiffer, but ...)The attenuation loss is about the same for solid copper as it is for copper clad steel because the signals travel on the surface of the center conductor, which is called the "Skin Effect." The copper clad steel is stiffer which means that center conductor can migrate toward the shield in a tight radius bend and contact the shield, which is called "Cold Flow" of the plastic foam dielectric.

http://forum.tvfool.com/attachment.php?attachmentid=2820&d=1501114379

There usually isn't a need for the stiffer Quad shield coax, but if you have a long run up to a preamp at the antenna, the preamp voltage drop will be less with a solid copper center conductor and a Quad shield.

Btw - any difference in net signal between screw on a crimp on connectors?Not that I'm aware of, but the screw on connector isn't reliable, the hex crimp is OK, but the compression connector is the most waterproof IF you use the correct size compression connector for the RG6 you have selected.

Nascarken
3-Feb-2019, 6:43 PM
But when using an mast mount amp you should use SOLiD copper 18 Gauge
That is what channel master says to use with the 7777 amp
Good luck with your antenna set-up

stephenson
4-Feb-2019, 7:27 PM
rabbit and nascarken,

Thanks for advice - I've got source of solid copper through Amazon - and, did more reading of effects present when going around corners with copper clad steel.

I didn't mean to hijack the thread, but if we're ok with that can I inquire about connectors and tools ...

Over the many years, I have crimped with crimp tool, crimped with pliers, used screw on fittings ... never any substantive issues worse than having to pull connector off and do it again. However, I was performing below industry standards and may have even lost the odd few db here and there.

Standards have changed a bit over the last few years - way more folks now using compression tools and fittings - looks like it minimizes call backs - all good.

Lots of options on the market - on both tools and connectors. I've already got a spin type trimming tool, but most kits come with one. Can you recommend a compression kit or manufacturer? Doesn't matter if it has connectors with it although most do. Many comment on some kits as being toy-like - I always try and buy quality tools so want to avoid those.

Thanks!

stephenson
4-Feb-2019, 9:14 PM
Decided to pull trigger on an Ideal 30-793 I found on ebay for $25 ... looks like it will do most everything.

I also checked my leftover RG 6 and connectors - the screw on ones I had were too small for the some of the coax I had anyway ... ha! Will order some compression connectors ...

stephenson
9-Feb-2019, 6:55 PM
Equipment arrived - temp antenna range in living room ... 41 channels, clunky interface right now using either Channels or HD Homerun app on iPad to ScreenMirror to the 3rd gen AppleTV box ... once get 4th or 4K AppleTV, should be very nice, indeed - Channels is pretty easy and probably gonna be worth the one time $25 for the app. Free on mobile devices.

Up in the attic next week and will see what happens - I think a few more channels. Then question is: would I get more channels with an amp ...?

stephenson
10-Feb-2019, 4:07 PM
Here's relative signal strength numbers for my install so far - have the antenna sitting in family room about 30" off floor (center) ...

Figured out where to get the signal characteristics: Signal Strength/Signal Quality/Symbol Quality

3 - 77/98/100
5 - 79/96/100
10 - 70/68/100
15 - 88/98/100
18 - 67/90/100
19 - 73/98/100
21 - 82/98/100
23 - 94/98/100
33 - 72/90/100
35 - 76/98/100
42 - 38/48/none
44 - 91/98/100
55 - 72/98/100

Nascarken
10-Feb-2019, 5:29 PM
Ok and how far away are the TOWER'S forum your antenna RECEIVE?

stephenson
12-Feb-2019, 2:15 PM
Thought I had posted TVFool data, above ... should just be able use the url, right?

Short answer is 18-30 miles for the ones I really wanted.

http://www.tvfool.com/?option=com_wrapper&Itemid=29&q=id%3d90389679234de3

Nascarken
12-Feb-2019, 2:36 PM
Ok cool sounds good I have a suggestion for you that would work well for you it's the new channels master antenna
Cm-3011HD&amp,cm-7778,and use a Jpole mount.

stephenson
12-Feb-2019, 6:33 PM
Thanks, but doing OK with the GE 29884 - just put it in the attic a few minutes ago - pointed 285T and all the signal strengths increased a bit ... got better WEIQ from Mobile so may be able to hold it, did lose Ch 19 from Pcola, but not a biggie - do ya think I could get it back by pointing 300T (120 + 180), instead of the 285? Would be backside of the antenna.

No preamp - doesn't look like one would help me much with current low cost approach?

Here's the numbers from floor to attic:
Update
ant floor ant attic
3 - 77/98/100 100/100/100
5 - 79/96/100 98/98/100
10 - 70/68/100 100/100/100
15 - 88/98/100 100/100/100
18 - 67/90/100 90/100/100
19 - 73/98/100 lost
21 - 82/98/100 100/100/100
23 - 94/98/100 100/100/100
33 - 72/90/100 100/100/100
35 - 76/98/100 92/98/100
42 - 38/48/none 73/90/100
44 - 91/98/100 100/100/100
55 - 72/98/100 91/98/100

stephenson
14-Feb-2019, 11:38 PM
Checked pointing ... was a bit off - closer to 279, so repointed to 285 ... got 19 back with only noticeable thing being slight signal degradation on 42.

JoeAZ
15-Feb-2019, 12:28 PM
Those GE antennas are quite sensitive to not only side to
side aiming but up/down aiming as well. You may want
to experiment and see if pointing skyward slightly gives you
better signals.....

Nascarken
20-Feb-2019, 11:18 PM
You should try stacking them like 4 ANTENNAS in a square 3ft apart by 3ft apart
I bet it will be out of this world!!

MikeBear
4-Jan-2020, 12:17 PM
The latest version of this RCA (VOXX) has out is labeled ANT752E.

The instruction manual and box photos to put it together shows a photo of the ANT751, and doesn't even quite match what the antenna is presently built like. Instructions are off, and it's hard to tell just exactly how they want you to put it together.

I've just picked one up for my dad, but I haven't installed it as of yet to see if it's any good. Hopefully it is, and works well for him.

Edit, 3:57pm:

Well, I decided to try out this antenna before taking it 50+ miles away and installing it at my dad's. I just put the J-mount on our outside raised deck railing (split level house), and screwed it down with two screws. I then mounted the antenna to it, and hooked it up to a 25' length of Walmart pre-packaged RG-6. So, it's about 9ft off ground level, and surrounded by trees. I then screwed the coax into the back of my 2013 LG tv set.

Works VERY well! Aimed towards WEYI-25 which is South-West, it picks up all my local channels, which are within a 35 to 47 miles radius. Including WJRT-12, which is on RF12 high vhf. It picks up but doesn't lock the two 10KW low powered stations (WFFC & WFKB) that are 32 miles away like my HDB91x does, but that antenna is mounted 15' higher up.

All in all, a good small low profile antenna for those that can only use a smaller unobtrusive one, and that the mud-flap antennas aren't quite good enough. As tiny as this antenna is, I'm AMAZED it works so well even without any sort of preamp, and only 8ft off the ground during this test.

OTAFAN
4-Jan-2020, 9:31 PM
Hi MikeBear:

Thanks for the update on the latest version of this good work horse of an antenna. I don't know if this link to RCA is the same as you bought, but it's the only one labeled close to what you mentioned above:

https://www.rcaantennas.net/outdoor/?sku=ANT752Z

Probably due to monetary issues, RCA seems to "downsize" some of their antennas every time they "update" a model. Rabbit73 mentioned this earlier in this thread in post 16. The link above shows one less element and no Tetrapole. Is this the antenna you bought for your Dad?

http://forum.tvfool.com/showpost.php?p=57828&postcount=16

However, the bottom line on any antenna is the reception it gives you at your location. Obviously you folks are happy with its performance, so congratulations and enjoy!

MikeBear
4-Jan-2020, 10:12 PM
Hi MikeBear:

Thanks for the update on the latest version of this good work horse of an antenna. I don't know if this link to RCA is the same as you bought, but it's the only one labeled close to what you mentioned above:

https://www.rcaantennas.net/outdoor/?sku=ANT752Z

Probably due to monetary issues, RCA seems to "downsize" some of their antennas every time they "update" a model. @Rabbit73 mentioned this earlier in this thread in post 16. The link above shows one less element and no Tetrapole. Is this the antenna you bought for your Dad?

http://forum.tvfool.com/showpost.php?p=57828&postcount=16

However, the bottom line on any antenna is the reception it gives you at your location. Obviously you folks are happy with its performance, so congratulations and enjoy!

Well, the Menard's store has the internet page ad labeled as ANT752Z, and that's what I thought I was getting. However in the store, the box is labeled ANT752E.

It's even slightly different than your link above, but real close. The only difference is that it has no complete Tetrapole, though it does have the top "wing" elements of the Tetrapole. Almost like it's now just an extra element (but thinner than the regular ones), and I swung them out and am using them as a element. There's nothing about that in the instructions, as the instructions don't even completely match the present antenna! So even though they update the antenna itself, they don't bother with updating the instructions.

The front half of the mast connects to the back half, and there's a separate set of aluminum phasing wires coming off of the single 1/2 Tetrapole sort of element, that screw down with nuts to the first elements of the back half.

Not having a Tetrapole really concerned me at first. However, it doesn't seem to make a whole lot of difference.

Edit: Whoops, looking at your link above again of the ANT7511, what I call the "top wing" elements of the Tetrapole, seems to be what @Rabbit73 shows screwed down to the rear section elements. He shows the aluminum wires he calls "shorting stubs" just hanging in the air alongside the boom. Is that the way it's meant to be installed? Can't tell from the instructions, as it doesn't show it.

I swung up the "top wing" elements, and stuck what Rabbit calls the "shorting stubs" under the nuts and tightened them down that way. I wonder if it'll work better the way Rabbit has it?

rabbit73
5-Jan-2020, 3:02 PM
Well, the Menard's store has the internet page ad labeled as ANT752Z, and that's what I thought I was getting. However in the store, the box is labeled ANT752E.
I really hate what RCA is doing with that antenna. The original 751 was a good design, but they have messed with it so many times it's difficult to know what version will be in the box you buy. It was originally introduced at the 2009 CES. AVS forum member holl_ands was there and he took some photos of it. I added some notes:

https://forum.tvfool.com/attachment.php?attachmentid=3608&d=1578239298

https://forum.tvfool.com/attachment.php?attachmentid=3473&d=1565191530

The design was based on a patent by John Winegard that shows a 3/4 wave folded dipole which he called a "Tetrapole," 1/4 wave shorting stubs, and director pairs:

https://forum.tvfool.com/attachment.php?attachmentid=3476&d=1565204259

http://forum.tvfool.com/attachment.php?attachmentid= 2610&stc=1&d=1491962883

The 751 is a combo antenna that receives UHF and VHF-High signals. The problem with a combo antenna is that the UHF section receives UHF signals and the VHF section receives VHF signals AND UHF signals. The UHF signals from the VHF section will interfere with the UHF signals from the UHF section, so they must be removed before the two sections are combined in one feedline. The conventional way to combine a UHF antenna and a VHF antenna is to use a UVSJ (UHF-VHF Separator-Joiner) which keeps the signals separated.

A UVSJ contains a low-pass filter and a high-pass filter. The low-pass filter passes VHF signals and blocks the UHF signals. The high-pass filter passes the UHF signals and blocks the VHF signals. It is an efficient low-loss device.

https://i.imgur.com/8F56qMa.png

The Winegard Tetrapole and 1/4 wave shorting stubs act as a substitute UVSJ. The 1/4 wave shorting stubs at the top of the Tetrapole remove the UHF signals coming from the VHF section and the Tetrapole combines the VHF signals and UHF signals at the feedpoint on the bottom of the Tetrapole. Any VHF signals received by the UHF section are ignored because the UHF section isn't very good at receiving VHF signals; they will be very weak.

The function of the shorting stubs is based on transmission line theory which says that the open end of a 1/4 wave stub that is not connected is a high impedance point which makes the other end that is connected is a very low impedance point which shorts out any signals at the resonant frequency of the stub. The 751 has 4 stubs formed by two strips that are fastened off center. This makes two pairs of stubs, one long pair for the low end of UHF and one short pair for the high end of UHF.

rabbit73
5-Jan-2020, 6:53 PM
Here is an illustration of the shorting stubs which M. J. Salvati calls an Isolation Network (see attachments):

http://forum.tvfool.com/attachment.php?attachmentid=2611&stc=1&d=1491963344

The shorting stubs must be attached an odd number of 1/4 waves away from the UHF feedpoint. If they were attached to the feedpoint, they would short out the UHF signals. In the RCA ANT 751, they are attached to the top of the Tetrapole, which is 3/4 wavelength before the feedpoint through the Tetrapole.

In the RCA ANT7511, they are attached 1/4 wavelength away from the UHF feedpoint, B to C:

https://forum.tvfool.com/attachment.php?attachmentid=3611&d=1578254950

There are only two wire stubs on the 7511, which really isn't sufficient to cover the whole UHF band. The wires with one end not connected are a little longer because they aren't as wide as the flat strips. The 751 uses two sets of flat wide stubs to cover the UHF band; much more effective.

rabbit73
5-Jan-2020, 7:56 PM
This is what the original RCA ANT751 looks like:

http://forum.tvfool.com/attachment.php?attachmentid=2614&d=1492288273

This is what the RCA ANT7511 looks like:

https://i.imgur.com/37y5miY.jpg

https://forum.tvfool.com/attachment.php?attachmentid=3612&d=1578258791


Differences between the original RCA ANT751 and the RCA ANT7511

751 7511

UHF Driven Element Tetrapole Long Dipole
VHF Directors 2 1
UHF Directors 1 Director Pair 3 Conventional
2 Conventional
Shorting Stubs 2 Pairs 1 Pair of thin wires
Mount At rear Between VHF elements

If you get the 7511, it will work, but not as well as the original 751. The 7511 has less gain, but you probably will not notice the difference in strong signal areas; it might make difference with weak marginal signals.

https://forum.tvfool.com/attachment.php?attachmentid=3613&d=1578260589

Maybe the only way left to get the original is to buy it from Denny.
http://dennysantennaservice.com/ez_hd_tv_Antenna.html

MikeBear
5-Jan-2020, 10:06 PM
Thanks Rabbit, I appreciate the info.

Anyway, I hooked up that RCA ANT752E antenna inside my dads apt, and all UHF local channels come in fine with the antenna aimed sort of in the middle of his local towers to balance the signal as best I could (Flint-Saginaw-Bay City DMA). However, there's not even a HINT of signal for WJRT-12, which is high VHF RF12. Cement and steel bldg, must be blocking it, or some electrical device in the building might be jamming it. I couldn't believe there wasn't even a hint of signal, and I even tried an older PA19 preamp I had that's still good. Didn't help for WJRT-12, but did jack up the signals for the UHF channels. However, since I didn't need those jacked up, I removed the preamp.

They won't allow an outside antenna though. Oh well, he wanted MeTV on 12.2, but he'll have to do without it. This will pay for itself quickly, over a $100 a month Charter/Spectrum tv bill.

I wish there was a better combo UHF/VHF antenna about the same size as this one, and with the same width of reception that gets a higher signal level for high VHF. I guess though even at double the VHF db level of this one I installed, there's still no guarantee it could get WJRT, but it would be nice.

If I could find an original ANT751, is it really that much better at high VHF?

I do have a spare Stellar Labs 30-2475 antenna and a Radio Shack UVSJ to combine it that he could use, but I just don't have the room available to install it with the ANT752E already installed.