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OTA recommendations for deep fringe

post #1 of 58
Thread Starter 
I'm looking into installing an OTA solution here (zip 78643). With the exception of one station, which I can get with a small indoor antenna, all of the others are pretty distant. Here's what tvfool.com shows for my address with respect to digitals in 2009, assuming mount 20' AGL (15' to top of roof plus 5' mast):

There are two concerns here. The first is KTBC-DT which is moving from its current 56 to 7 next year. I've been looking into it, and at first it seemed like a combination of CM4228 and CM7777 preamp would be enough. But if KTBC is moving from 56 to 7, a UHF-only solution wouldn't work as it would today. Some have reported that there is a little high VHF gain with the 4228, but not as much on 7 as with 9-13. So I doubt that would be sufficient. As a result I might need a different solution that also has at least high VHF, or a separate VHF antenna (a YA-1713, maybe?) in addition to a 4228. That seems to be a popular combination for fringe reception.

The other concern is overloading on KXAM-DT. This is one that could come in loud and clear with an indoor coat hanger antenna. While all the other stations in the 119 and 120 directions seem to need a preamp, I think KXAM could cause problems with overloading on a preamp. Would that mean splitting out channel 27 somehow, using an attenuator on that split and then multiplexing them back together?

I'm really only interested in the signals from the same antenna farm in Austin, which are the six lines clustered above which are 59-60 miles away and at 119-120 azimuth. So I don't really think a rotor is necessary even with a strictly directional solution.

Any thoughts about the setup, specific antenna recommendations, anything else? Am I at least on the right track here? Are these even strong enough to pick up with a large deep fringe antenna?
post #2 of 58
I would go with a Terrestrial Digital 91-XG with a rotor and pre-amp if it were me; much better antenna for those distances; you would need that separate VHF though; We'll have 4 stations on VHF in feb. so will need one myself. I hear the Wade-Delphi 306 is the best fringe antenna made--just go to tigerbangs prescription for deep fringe reception and read that info.
post #3 of 58
Thread Starter 
Quote:
Originally Posted by bozey45 View Post

I would go with a Terrestrial Digital 91-XG with a rotor and pre-amp if it were me; much better antenna for those distances; you would need that separate VHF though; We'll have 4 stations on VHF in feb. so will need one myself. I hear the Wade-Delphi 306 is the best fringe antenna made--just go to tigerbangs prescription for deep fringe reception and read that info.

Thanks. You think I need the rotor, though? All the stations I'm trying to pick up are all aligned within one degree of each other.

Based on best line of sight, I'm thinking of mounting on top of my detached garage (no trees in the way there) and running a line from there to the house (a run of about 50 feet). I'm not sure operating a rotor to a garage roof-mounted antenna is that feasible. I don't mind the extra cost if it helped, but I didn't really think it seemed necessary given the location of the transmitters. And I'm not going to pretend I can reach the San Antonio or the Waco-Temple-Bryan locals, which are about the only other things I could try (being about 90-100 mostly hilly miles away).

I've heard some people mention the 91-XG as well as a couple of Winegard models in addition to the CM 4228. I'd love to get some local opinions, but I think what few people there are in town have all been doing satellite for years now.
post #4 of 58
Your best bet us to get your antenna higher. The low signal strengths shown do not bode well for getting any digital lock. Even an additional 10 feet could make a significant difference.
post #5 of 58
You might consider a channel 27 Jointenna if you can find one to kill KXAM down to a reasonable power level. Antenna, then Jointenna, then preamp.
post #6 of 58
Thread Starter 
Quote:
Originally Posted by n4yqt View Post

Since your chart shows VHF-Lo, VHF-High, and UHF channels...

Thanks. I'm not terribly concerned about picking up KCWX well, and KAKW is a Spanish language station I don't need.

So really what I need is a way to receive the remaining six stations with -101 to -108 signal (likely with a UHF antenna and a high VHF antenna) combined with a reduced signal from KXAM into the preamp. I think that's the general idea.

Would it be possible to filter out ch 27 completely from the antenna (so it never goes through the preamp) and then join it back in with a set-top antenna near the tuner? I get mid- to high-80s from it with a small indoor antenna now.

I could get an extra 6' or 7' of height if I mounted it rooftop on the house instead of the garage, but there's a huge pecan tree in the way. I might be able to find a spot along the ridgeline where it's unobstructed and has a clear view of the horizon. I'm a little worried about a mast more than 5' tall due to wind concerns, so at most I'd be able to get it about 25' up from the ground.
post #7 of 58
that was the purpose of the Jointenna - to cut down on the input from the close, powerful channel 27. You're still not going to knock it out completely, but rather just weaken it enough that it doesn't over extend the preamp needed for all the other stations you're interested in.
post #8 of 58
A 91XG and a YA1713 on a mast should serve you well.

I would try it w/o a pre-amp first, but one will probably be needed. I agree that the 7777 is going to have problems with KXAM. In addition to the jointenna options noted above, you can have a custom notch filter made for 27 (~30dB), but they are expensive.

A jointenna for 27 can act as a cheap notch filter if you put a terminator on the 27 input and feed the rest through the "all channels" input. The jointenna has a wide notch, but 21, 22 and 33 should be far enough away.

There are higher input pre-amps, but with KXAM being above 40dB, it is likely that they will all overload. A Winegard 8700 pre-amp may provide more of a margin for error, but it will still need filter help for 27. It also depends on how many splits you will need.

KCWX/5 petitioned the FCC to not use channel 5 for DTV, but it was denied in March. I wouldn't be surprised to see them try to move again down the road. If you can get the other CW, it may be moot anyway?
post #9 of 58
For the UHF stations at 120, you could try a 91XG or 4228 with a 7777 pre-amp and a Channel 27 jointenna configured as a bandstop filter (single-channel input terminated). My gut feel though is that this will not be enough to keep 27 from overloading the pre-amp, and any lesser pre-amp won't be able to receive the distant signals.

Tinlee makes a "Semi-adjacent channel eliminator" (CR-7E) filter which you could use to knock out UHF 27 before the pre-amp; with 50+dB attenuation it's just what the doctor ordered. I have no idea how much it costs but it probably isn't cheap. If you wanted 27 you could put up another small antenna (even indoors) and join it in with a Jointenna _after_ the pre-amp. Theoretically you could split, filter, amplify, and re-join with one antenna but you'll lose 3dB that way, and you probably can't afford that 3dB.

Add a YA-1713 for channel 7, and put that into the VHF input of the 7777. Some people have reported that using the VHF input of the 7777 degrades UHF performance, if that is a problem you could use a separate VHF amp and a UVSJ, though getting power to both amps becomes an issue.

Sadly there's no guarantee that the setup will work after all of this.
post #10 of 58
Thread Starter 
Quote:
Originally Posted by Rick0725 View Post

-ch 13 92 degrees - 10 element ch 13 vhf yagi with ch 13 jointenna no amplification 36$

...

you are going to need two ya1713's or single channel vhf antennas. ch 13 is at 92 degrees and ch 7 is at 120 degrees. that is a almost a 30 degree difference...compromise anxiety is what I foresee with 1 antenna.

Channel 13 is a Spanish language station. I don't need it. At least that slightly simplifies things on the VHF side, I'd think, since I'd really only be concerned about 7. I suppose I could add another low-VHF yagi later if I wanted to get 5.

At first I'd want to concentrate on the six stations at 120 plus preventing the signal on 27 from messing it all up. As you mentioned, that they are so close in direction (120 and 128) is problematic too because even a highly directional antenna like a 91-XG will get them both, even if I didn't want it to pick up 27.

I'd probably start simply and build it in stages -- first getting the UHFs at 119-120 (while reducing the signal from ch 27), then adding the yagi for 7. And after that, if I wanted 5, I could try that as well.

I'll have to read up more on the Jointennas, since based on the responses it looks like that might have to be part of the solution.
post #11 of 58
post #12 of 58
Thread Starter 
Quote:

Thanks. It definitely seems like I'd want to do that if I decided to join both 7 and 5 at some point with two separate yagis. (At the moment I don't really need 5 if I could get 49, even though 5 is much closer.). If I didn't add 5, I wouldn't need that jointenna on the VHF side.

As for using one to block 27, let me make sure I have it right. If I put a terminator cap on the 27 input and put the rest of the UHF (such as from a 91-XG) in the other input, then the output would go to the preamp, thus preventing 27 from overwhelming the preamp? And then I'd have to join 27 back in with a separate, non-amplified small directional antenna with another 27 jointenna on the other side of the preamp?

Am I close?
post #13 of 58
Best thing is to try without the rotor then and see how reception is for you, then if you need it, add it.
post #14 of 58
Yes - what a jointenna is doing is blocking the RF channel (and to a lesser degree, the ones around it) to allow you to insert another antenna in place. Think of the curve as a kind of funnel, with the "assigned frequency" being the hole in the bottom (or actually - pretty close but not completely down the hole). The "Width" is usually about 2-3 channels on either side.
post #15 of 58
Threre may still be enough of channel 27's signal remaning even after reducing it with the Jointenna before the preamp that you would not need to re-insert 27 down the line. Every splitter or combiner induces some loss.
If you wanted to try for the channel 5 later with a seperate VHF low band antenna it could be combined with the channel 7 antenna with a simple Pico Macom HLSJ VHF high/low combiner rather than another Jointenna.
post #16 of 58
Thread Starter 
Quote:
Originally Posted by Rick0725 View Post

I suggested a smaller lower gain uhf antenna with jointenna dedicated for ch27. The combination of lower antenna gain, no amplification, and filtering will be a big benefit in getting this situation to work. as opposed to using the higher gain antenna with an amp and trying to filter ch 27 signal level down.

I get that -- but ch 27 is at 128 and the other distant stations are at 119-120. Seems like aiming the 91XG to 120 would also pull in a close and powerful signal at 128...and overwhelm the preamp? That's why I assumed a jointenna would be needed as a notch filter to kill 27 before going to the preamp -- otherwise, the strong signal on 27 goes into the preamp and overpowers it...wouldn't it?
post #17 of 58
I tried my channel 31 join-tenna as a filter. I was still able to receive KTLA 31 with it, but it acted like a 20-30dB attenuator (I compared it with 20dB and 10dB attenuators). It did not affect channels close to it as much as I thought it would. However, 20-30dB may not be enough attenuation for your channel 27, especially with a 7777.

However, you may find that you don't need a pre-amp. Try out the 91XG first and see what you get. TV Fool is a good tool, but only real world testing can provide exact results and you may be surprised.

Just be warned that the 91XG will eat your fingers when putting it together. Some assembly required!

You can try assembling the first section (reflectors and 1st boom) to test and then add the boom extensions later, but that's probably not as convenient if you have it on the roof.

As long as you don't have something like a 60dB notch, you will probably still get 27 on the main UHF antenna. I think it's going to be quite difficult to filter it out completely. In other words, I don't see a need for a separate antenna for 27.
post #18 of 58
Thread Starter 
Quote:
Originally Posted by Falcon_77 View Post

However, you may find that you don't need a pre-amp. Try out the 91XG first and see what you get. TV Fool is a good tool, but only real world testing can provide exact results and you may be surprised.

The good news is that I'm not in a rush, so I won't go out and buy everything I might need. I'll start with the 91XG, the yagi for ch 7 and a UVSJ to combine the VHF and UHF signals, since I know I'll need those. From there I can see what else I need to do about a preamp. If I need a preamp (and I'd certainly guess I would for the towers 60 miles away), I'd check to see if ch 27 is too strong and causes trouble (if I need attenuation of 27 before going into the preamp).

For now this is basically a hobby project for me and I get most of this stuff on satellite now, but I don't know that I want to keep paying $70-80 a month for it indefinitely. But I do have the luxury of taking my time, not overbuying immediately and only buying additional stuff as it becomes obvious I need it. I know there are large OTA antennas around town which look to be aimed at 120, so presumably it's possible but may not be easy.
post #19 of 58
Thread Starter 
Update: Got my 91XG today. I'm in the middle of assembling it.

One question about the balun. I'm not sure which way to install it. I know to put it on the underside, but does the coax connector point toward the end of the boom, or toward the middle of it?

(I'm assuming middle, but it's not clear from the instructions and I haven't seen a large enough picture of that part of it to know for sure.)
post #20 of 58
Quote:
Originally Posted by ziggy29 View Post

One question about the balun. I'm not sure which way to install it. I know to put it on the underside, but does the coax connector point toward the end of the boom, or toward the middle of it?

I put mine on to face towards the end to have the Coax go out that back. I don't remember it being bi-directional but perhaps I didn't notice. It is 3000 miles away, otherwise I'd check.
post #21 of 58
Thread Starter 
Thanks. I reversed the balun so that the connection to the coax comes in through the back rather than the center. Fingers are fine. I bent a couple of the elements but straightened them out. Hopefully it's not a problem. Looks like it's all together. Tomorrow I'll grab some coax, attach the antenna to a mast and start feeling around for a signal. May not get it except on 27 without a preamp, but this is just the first step of many.
post #22 of 58
Thread Starter 
All I can say is...wow.

Today I started the first round of testing with the 91XG. I set the antenna out in the appropriate direction, resting on a large trash can about 4' high, and with bricks around it to keep it upright and stationary.

Coming into the DirecTV HR20-700, the signal meters were as high as the 70s...with NO preamp and a 100-foot spool of RG-6 between it and the antenna. Channels 21, 22 and 33 were all in the high 60s and low 70s with a great picture. 43 and 56 weren't quite as strong -- in the 40s and low 50s -- but the picture quality was almost always very high. 49 barely came in at all, which was to be expected based on the TVFool information.

Again, this is with NO preamp and only about 5' off the ground, with a lot of trees in the path. I think I can declare Phase 1 to be a smashing success, and now I can start thinking about a permanent mount and preamp. The signal on 27 was in the high 80s; maybe the 8 degree offset might have been enough to prevent it from a stronger signal.

I may not even need as strong a preamp as I might have thought with this setup, and to keep 27 from overloading, maybe I don't need maximum gain.

EDIT to add: I just put the antenna on the end of an old rake along the side of the garage to see if I could do a wall mount instead of climbing on the roof. I had my wife shouting out the results on the signal meter. I was pulling in high 70s and 80s on all the stations except for 49 which was in the 50s. And I wasn't anally microadjusting the direction but merely pointing it in roughly the right direction. Now I can go ahead and get the wall mounting supplies and a mast. I may hold off on the high VHF yagi since ch 7 will still be on 56 until Feb '09.

Thanks at all for the tips. It can be done way out in the boonies!
post #23 of 58
Thank you for the update. I'm glad that the initial tests have turned out well. If you can mount the antenna where you don't need a pre-amp, it will reduce overload concerns.

I'm not familiar with the D* tuner, but the signal could be in the 80's due to it being too strong. Does it go to 100? As long as you get enough for a lock, the picture quality shouldn't change between, say 40 and 100. It's all, nothing or dropouts.

Thanks again for the report.
post #24 of 58
Thread Starter 
I don't think it's overloading because the signal on 27 was in the mid-90s when I aimed the antenna a few degrees clockwise (right at 128). If there was overloading I would expect the signal to be lower, not higher, at 128 than when aimed at about 120.

Still, because of the issue with ch 27 I'd prefer to not even use a preamp at all if I can avoid it (plus the extra cost and complexity). I suspect I'll mount the antenna on the wall, with the antenna about 3 feet above the roof line, and if that gives me an adequate picture on all the channels I'm trying to lock in, maybe I'm done. Just need to figure out the grounding and such.

I'm still amazed at the strength of these signals and the picture quality with zero amplification across 60 hilly miles, with no more than about 12' AGL and with a ridge partially obscuring the signal between me and the towers about 8 miles from here. (That ridge is actually where the KXAM tower is located.)
post #25 of 58
I wouldn't worry about using a preamp. Something with 20 db gain should be just fine. I have many more stations at your -40 dbm level, and get best reception using a Winegard AP4800 so far. My weakest that are receivable are in the -85 dbm range. I have not yet received any in the -100 area but may be due to all my strong stations here in Boston area.

My antennas are dual Blake yagis and look very similar to your 91XG.

I did the filter thing too with far more expensive filters than the jointenna, but they overall didn't help. There were losses across the whole band that were unacceptable.

I am currently planning to try better preamps next.

I'd suggest you read this thread:

http://www.satelliteguys.us/hd-over-...mendation.html
post #26 of 58
Wrong. I have all kinds of preamps and the 4800 works the best and my signals per tvfool are in the same range from strong to weak.

I've used both Channel master and Winegard preamps with lower gain with far worse results as well as using no preamp. Only the 4800 comes even close to getting me stations in the -80 dbm range.

As to what overloads where I'm sure every location is different because you need to account for what is in the antenna's beam, but saying it can't work is just not true. I got that same advice and avoided buying the 4800 till long after every other option failed to work.
post #27 of 58
Forgive my ignorance, but I am just beginning to learn about trying to receive OTA. Will the overamplified signal acutally cause equipment damage or will it just give a lousy picture?
post #28 of 58
Too strong of signals are just as bad as too weak, in their own way. Been there, done that.....
post #29 of 58
Quote:
Originally Posted by jjmiller1 View Post

Forgive my ignorance, but I am just beginning to learn about trying to receive OTA. Will the overamplified signal acutally cause equipment damage or will it just give a lousy picture?

In the DTV world, a signal that is too strong will result in no picture. Possibly not for that particular channel, but for others as a result of intermodulation products (effectively noise).

Using amps in a strong signal area (especially those indoor amplified solutions), can easily cause more problems than they solve.
post #30 of 58
Quote:
Originally Posted by Falcon_77 View Post

In the DTV world, a signal that is too strong will result in no picture. Possibly not for that particular channel, but for others as a result of intermodulation products (effectively noise).

Note that with this mechanism, strong analog channels figure into the mix because they can overload the amp and thereby mess up reception on digital channels that might otherwise be OK.
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