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Old 25-Jun-2017, 3:14 AM   #81
OTAFAN
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Rca ant751

[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!
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Old 25-Jun-2017, 3:04 PM   #82
rabbit73
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Quote:
Originally Posted by OTAFAN View Post
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.
Quote:
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.
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File Type: jpg AD Element Ant1.jpg (77.8 KB, 871 views)
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Last edited by rabbit73; 25-Jun-2017 at 3:11 PM.
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Old 4-Oct-2017, 11:01 PM   #83
kennylive
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Licencing fee

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.
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Old 6-Oct-2017, 10:31 PM   #84
OTAFAN
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Rca ant751

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,
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Old 7-Oct-2017, 11:57 PM   #85
kennylive
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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.
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Old 8-Oct-2017, 1:09 AM   #86
OTAFAN
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Rca ant751

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.
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Old 28-Apr-2018, 1:43 AM   #87
gmcjetpilot
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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.

Last edited by gmcjetpilot; 28-Apr-2018 at 2:02 AM.
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Old 28-Apr-2018, 3:31 AM   #88
OTAFAN
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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.
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Old 28-Apr-2018, 10:57 AM   #89
Nascarken
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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.
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Old 28-Apr-2018, 7:54 PM   #90
OTAFAN
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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!
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