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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, 310 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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