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!

http://forum.tvfool.com/attachment.p...1&d=1498402788

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.
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.

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.

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, :)

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.

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.

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.

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.

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.

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!

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_wr...9038290b2ad724

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!

Thank you for your kind words; you are welcome.

The 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.
The 29884 is more sturdy.

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?

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.p...0&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.

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.

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

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!

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 ...

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 ...?

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

Ok and how far away are the TOWER'S forum your antenna RECEIVE?

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_wr...90389679234de3

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.

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

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.

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.....

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!!

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.

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...8&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?

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....8&d=1578239298

https://forum.tvfool.com/attachment....3&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....6&d=1565204259

http://forum.tvfool.com/attachment.p...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.

Here is an illustration of the shorting stubs which M. J. Salvati calls an Isolation Network (see attachments):

http://forum.tvfool.com/attachment.p...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....1&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.

This is what the original RCA ANT751 looks like:

http://forum.tvfool.com/attachment.p...4&d=1492288273

This is what the RCA ANT7511 looks like:

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

https://forum.tvfool.com/attachment....2&d=1578258791

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....3&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

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.